A Single Precursor Protein for Ferrochelatase-I fromArabidopsis Is Imported in Vitro into Both Chloroplasts and Mitochondria

Ferrochelatase is the last enzyme of heme biosynthesis and in higher plants is found in both chloroplasts and mitochondria. We have isolated cDNAs for two isoforms of ferrochelatase from Arabidopsis thaliana, both of which are imported into isolated chloroplasts. In this paper we show that ferrochelatase-I is also imported into isolated pea mitochondria with approximately the same efficiency as into chloroplasts. Processing of the precursor was observed with both chloroplast stroma and mitochondrial matrix extracts. This was inhibited by EDTA, indicating it was due to the specific processing proteases. The specificity of import was verified by the fact that the mitochondrial preparation did not import the precursor of the light-harvesting chlorophylla/b protein precursor or the precursor of porphobilinogen deaminase, an earlier enzyme of tetrapyrrole biosynthesis, both of which are exclusively chloroplast-located. Furthermore, import of ferrochelatase-I precursor into mitochondria was inhibited by valinomycin, but this had no effect on its import into chloroplasts. Thus a single precursor molecule is recognized by the import machinery of the two organelles. The implications for the targeting of ferrochelatase in a possible protective role against photooxidative stress are discussed. Ferrochelatase is the last enzyme of heme biosynthesis and in higher plants is found in both chloroplasts and mitochondria. We have isolated cDNAs for two isoforms of ferrochelatase from Arabidopsis thaliana, both of which are imported into isolated chloroplasts. In this paper we show that ferrochelatase-I is also imported into isolated pea mitochondria with approximately the same efficiency as into chloroplasts. Processing of the precursor was observed with both chloroplast stroma and mitochondrial matrix extracts. This was inhibited by EDTA, indicating it was due to the specific processing proteases. The specificity of import was verified by the fact that the mitochondrial preparation did not import the precursor of the light-harvesting chlorophylla/b protein precursor or the precursor of porphobilinogen deaminase, an earlier enzyme of tetrapyrrole biosynthesis, both of which are exclusively chloroplast-located. Furthermore, import of ferrochelatase-I precursor into mitochondria was inhibited by valinomycin, but this had no effect on its import into chloroplasts. Thus a single precursor molecule is recognized by the import machinery of the two organelles. The implications for the targeting of ferrochelatase in a possible protective role against photooxidative stress are discussed. Correct targeting of nuclear-encoded proteins within the eukaryotic cell is essential for its function and for the biogenesis of the various organelles. The majority of proteins destined for the mitochondria or chloroplasts are synthesized initially as precursors with N-terminal extensions. These serve as transit peptides to direct the protein to receptors on the surface of the organelle and are generally removed during or after import by specific processing proteases. Analysis of each class of transit peptide has revealed that there is little conservation at the primary sequence level either in composition or in length, although some general features have been identified, such as the fact that mitochondrial presequences frequently form amphiphilic α-helices (1Von Heijne G. Steppuhn J. Herrmann R.G. Eur. J. Biochem. 1989; 180: 535-545Crossref PubMed Scopus (903) Google Scholar). It is generally considered that they are very specific and that the receptor machinery on the outer membranes of chloroplasts and mitochondria is able to discriminate between bona fide precursors and those which reside in another organelle. For example, the Nicotiana plumbaginifoliatransit peptide from the β subunit of F1-ATPase will direct proteins to plant mitochondria in vitro (2Chaumont F. O'Riordan V. Boutry M. J. Biol. Chem. 1990; 265: 16856-16862Abstract Full Text PDF PubMed Google Scholar, 3Whelan J. Knorpp C. Glaser E. Plant Mol. Biol. 1990; 14: 977-982Crossref PubMed Scopus (54) Google Scholar) orin vivo (4Boutry M. Nagy F. Poulsen C. Aoyagi K. Chua N.-H. Nature. 1987; 328: 340-342Crossref PubMed Scopus (93) Google Scholar), but not to chloroplasts. Similarly, chloroplast precursors such as the 33-kDa subunit of the photosynthetic water-splitting complex (OEC33) (3Whelan J. Knorpp C. Glaser E. Plant Mol. Biol. 1990; 14: 977-982Crossref PubMed Scopus (54) Google Scholar) or the chlorophylla/b-binding protein (2Chaumont F. O'Riordan V. Boutry M. J. Biol. Chem. 1990; 265: 16856-16862Abstract Full Text PDF PubMed Google Scholar) are not targeted to plant mitochondria.Conversely, there is evidence that some “mis-sorting” can occur with chloroplast transit peptides into fungal mitochondria and vice versa. For example, the transit peptide of the small subunit of ribulose-bisphosphate carboxylase (SSU) 1The abbreviations used are: SSU, small subunit of ribulose-bisphosphate carboxylase; COX, cytochrome oxidase; PAGE, polyacrylamide gel electrophoresis; NAD-ME, NAD-malic enzyme; LHCP, light-harvesting chlorophyll protein; Tes,N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid. 1The abbreviations used are: SSU, small subunit of ribulose-bisphosphate carboxylase; COX, cytochrome oxidase; PAGE, polyacrylamide gel electrophoresis; NAD-ME, NAD-malic enzyme; LHCP, light-harvesting chlorophyll protein; Tes,N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid. fromChlamydomonas directed the import of passenger proteins into yeast mitochondria both in vivo and in vitro (5Hurt E.C. Soltanifar N. Goldschmidt-Clermont M. Rochaix J.-D. Schatz G. EMBO J. 1986; 5: 1343-1350Crossref PubMed Google Scholar). In a reciprocal experiment, Huang et al. (6Huang J. Hack E. Thornburg R.W. Myers A.M. Plant Cell. 1990; 2: 1249-1260Crossref PubMed Scopus (62) Google Scholar) demonstrated that the yeast cytochrome oxidase subunit Va (COXVa) transit peptide directed chloramphenicol acetyltransferase to both chloroplasts and mitochondria in transgenic tobacco. However, both systems used artificial fusion proteins in heterologous systems, and both presequences used were atypical: that of the ChlamydomonasSSU has the potential to form an amphiphilic α-helix more typical of mitochondrial transit peptides (7Franzen L.-G. Rochaix J.-D. Von Heijne G. FEBS Lett. 1990; 260: 165-168Crossref PubMed Scopus (36) Google Scholar), whereas the yeast COXVa presequence was predicted to form an antiparallel β-sheet (8Cumsky M.G. Trueblood C.E. Ko C. Poynton R.O. Mol. Cell Biol. 1987; 7: 3511-3519Crossref PubMed Scopus (58) Google Scholar). Further, not there is no for mitochondria to have to discriminate between precursor not of proteins between chloroplasts and mitochondria in et al. G. Plant J. PubMed Scopus Google Scholar) have that of the for pea in transgenic plants in the targeting of the enzyme both to chloroplasts and to mitochondria. were also able to show that this targeting was due to the transit it was able to a acetyltransferase protein to both in This is not is found in and the 1990; 180: PubMed Scopus Google Scholar), but it is by a single in the protein the for targeting to is the last enzyme of heme biosynthesis, and its has been in both mitochondria and Biochem. J. PubMed Scopus Google Scholar). of a yeast in the we isolated a single for ferrochelatase from Arabidopsis J. Biol. Chem. Full Text PDF PubMed Google Scholar). The precursor protein by the was to targeted to chloroplasts in vitro and to the Furthermore, it was by pea but not by mitochondrial by mitochondrial processing from We that this was the chloroplast of the we isolated an by the same which into two on the of and and G. in and G. in The some was the same as the and was found to by the same The of cDNAs a ferrochelatase with to the ferrochelatase-I we had demonstrated that ferrochelatase-I was targeted to we that was the mitochondrial However, to import the precursor protein into isolated mitochondria were the protein was imported into chloroplasts and to the with an efficiency to that of the ferrochelatase-I precursor Eur. J. Biochem. PubMed Scopus Google Scholar). we had in and found a of ferrochelatase it was that there a of the This to the targeting of In this paper we which that the ferrochelatase-I protein is to both plant mitochondria and chloroplasts in have demonstrated that the precursor for ferrochelatase-I from Arabidopsis is imported into both mitochondria and chloroplasts from in vitro and to the of The import into mitochondria is not due to of the mitochondrial with it was by which the potential for protein import M. Eur. J. Biochem. PubMed Scopus Google Scholar). It also is not due to of by mitochondrial preparation there was no import of the exclusively chloroplast proteins or porphobilinogen Similarly, the pea chloroplasts not proteins that are found exclusively in mitochondria such as or not and also not ferrochelatase-I import into chloroplasts although the precursor to ferrochelatase-I was not in vitro with mitochondrial from J. Biol. Chem. Full Text PDF PubMed Google Scholar), we have been able to with mitochondrial from pea The for this is due to the of used in the two although some evidence of processing was with we observed processing with of pea mitochondrial more was used for the this was able to the precursor to yeast J. Biol. Chem. Full Text PDF PubMed Google Scholar). However, it also the fact that the ferrochelatase-I precursor is from a as is is a the precursor was with of pea mitochondrial protein The of ferrochelatase-I precursor by both chloroplast and mitochondrial was by the of EDTA, indicating that the processing was due to the processing both of which for C. Eur. J. Biochem. PubMed Scopus Google Scholar, J. Knorpp C. Glaser E. Plant Mol. Biol. PubMed Scopus Google Scholar, and G. Schatz G. J. Biol. Chem. Full Text PDF PubMed Google Scholar), which are in C. Plant 1989; PubMed Google protein which has been to targeted to both chloroplasts and mitochondria is from pea G. Plant J. PubMed Scopus Google Scholar). this was in vivo in transgenic it was not possible to the of targeting to the two was it possible to the of to the In the majority of is found in the chloroplasts with in mitochondria and the 1990; 180: PubMed Scopus Google Scholar). Thus that the import into mitochondria is the of This to the for with ferrochelatase-I it was imported with approximately the same efficiency into chloroplasts and mitochondria both from the same pea it were that import into organelle was an it to into the as was for the targeting to yeast mitochondria of passenger proteins to presequence (5Hurt E.C. Soltanifar N. Goldschmidt-Clermont M. Rochaix J.-D. Schatz G. EMBO J. 1986; 5: 1343-1350Crossref PubMed Google Scholar). are no of the of ferrochelatase between mitochondria and but and Biochem. J. PubMed Scopus Google Scholar) found that the specific was very in mitochondria and from and the two isoforms had very of and import efficiency for ferrochelatase by the fact that in chloroplasts there is a Eur. J. Biochem. PubMed Scopus Google direct evidence of targeting of ferrochelatase-I in the of precursor proteins in import in vitro has generally been to the in and there is no this not the for Furthermore, although it was that isoforms of an enzyme in were by as is the for M. of and of in Scholar) and C. PubMed Scopus Google Scholar), of proteins targeted to more are more For example, the mitochondrial and isoforms of Eur. J. Biochem. PubMed Scopus Google Scholar) and and from yeast PubMed Scopus Google Scholar) are each the of a single as are the and mitochondrial of in Arabidopsis Plant Cell. PubMed Scopus Google Scholar). Analysis of in the the of two potential in some the that the same to two has been for pea G. Plant J. PubMed Scopus Google or the for the targeting we have In there is a single protein of in the of to the predicted of the there is a in the the protein from this to a of which in the have implications for the of precursor by mitochondria and it that targeting is recognized by the chloroplast and mitochondrial import it that in vivo there is no that within the cell to targeting of ferrochelatase-I to or another organelle. to exclusively and is not in ferrochelatase-I is the mitochondrial These to ferrochelatase-I import into also that there ferrochelatase In of we have found class which is by such that the it from the the majority of the mitochondrial targeting this was able to a yeast of ferrochelatase was with a a form of yeast ferrochelatase J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The found that in this although there was ferrochelatase this was the membranes of the to the matrix of the mitochondrial which is the of ferrochelatase PubMed Scopus Google Scholar). The of heme synthesized in was with but this was to of the in ferrochelatase is not for heme J. Biol. Chem. 1990; 265: Full Text PDF PubMed Google Scholar). a during an is that this a form of ferrochelatase has been found with the which also of the enzyme of the tetrapyrrole oxidase Biochem. Scopus Google Scholar). The of this is as by the of the which this to Plant PubMed Google M. Biochem. J. 1989; 260: PubMed Scopus Google Scholar). In plants in the are which and cell Chem. Scholar). The of ferrochelatase in cell membranes a to that is and not to In this ferrochelatase have a role to which is also an of the plant to with Correct targeting of nuclear-encoded proteins within the eukaryotic cell is essential for its function and for the biogenesis of the various organelles. The majority of proteins destined for the mitochondria or chloroplasts are synthesized initially as precursors with N-terminal extensions. These serve as transit peptides to direct the protein to receptors on the surface of the organelle and are generally removed during or after import by specific processing proteases. Analysis of each class of transit peptide has revealed that there is little conservation at the primary sequence level either in composition or in length, although some general features have been identified, such as the fact that mitochondrial presequences frequently form amphiphilic α-helices (1Von Heijne G. Steppuhn J. Herrmann R.G. Eur. J. Biochem. 1989; 180: 535-545Crossref PubMed Scopus (903) Google Scholar). It is generally considered that they are very specific and that the receptor machinery on the outer membranes of chloroplasts and mitochondria is able to discriminate between bona fide precursors and those which reside in another organelle. For example, the Nicotiana plumbaginifoliatransit peptide from the β subunit of F1-ATPase will direct proteins to plant mitochondria in vitro (2Chaumont F. O'Riordan V. Boutry M. J. Biol. Chem. 1990; 265: 16856-16862Abstract Full Text PDF PubMed Google Scholar, 3Whelan J. Knorpp C. Glaser E. Plant Mol. Biol. 1990; 14: 977-982Crossref PubMed Scopus (54) Google Scholar) orin vivo (4Boutry M. Nagy F. Poulsen C. Aoyagi K. Chua N.-H. Nature. 1987; 328: 340-342Crossref PubMed Scopus (93) Google Scholar), but not to chloroplasts. Similarly, chloroplast precursors such as the 33-kDa subunit of the photosynthetic water-splitting complex (OEC33) (3Whelan J. Knorpp C. Glaser E. Plant Mol. Biol. 1990; 14: 977-982Crossref PubMed Scopus (54) Google Scholar) or the chlorophylla/b-binding protein (2Chaumont F. O'Riordan V. Boutry M. J. Biol. Chem. 1990; 265: 16856-16862Abstract Full Text PDF PubMed Google Scholar) are not targeted to plant mitochondria. there is evidence that some “mis-sorting” can occur with chloroplast transit peptides into fungal mitochondria and vice versa. For example, the transit peptide of the small subunit of ribulose-bisphosphate carboxylase (SSU) 1The abbreviations used are: SSU, small subunit of ribulose-bisphosphate carboxylase; COX, cytochrome oxidase; PAGE, polyacrylamide gel electrophoresis; NAD-ME, NAD-malic enzyme; LHCP, light-harvesting chlorophyll protein; Tes,N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid. 1The abbreviations used are: SSU, small subunit of ribulose-bisphosphate carboxylase; COX, cytochrome oxidase; PAGE, polyacrylamide gel electrophoresis; NAD-ME, NAD-malic enzyme; LHCP, light-harvesting chlorophyll protein; Tes,N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid. fromChlamydomonas directed the import of passenger proteins into yeast mitochondria both in vivo and in vitro (5Hurt E.C. Soltanifar N. Goldschmidt-Clermont M. Rochaix J.-D. Schatz G. EMBO J. 1986; 5: 1343-1350Crossref PubMed Google Scholar). In a reciprocal experiment, Huang et al. (6Huang J. Hack E. Thornburg R.W. Myers A.M. Plant Cell. 1990; 2: 1249-1260Crossref PubMed Scopus (62) Google Scholar) demonstrated that the yeast cytochrome oxidase subunit Va (COXVa) transit peptide directed chloramphenicol acetyltransferase to both chloroplasts and mitochondria in transgenic tobacco. However, both systems used artificial fusion proteins in heterologous systems, and both presequences used were atypical: that of the ChlamydomonasSSU has the potential to form an amphiphilic α-helix more typical of mitochondrial transit peptides (7Franzen L.-G. Rochaix J.-D. Von Heijne G. FEBS Lett. 1990; 260: 165-168Crossref PubMed Scopus (36) Google Scholar), whereas the yeast COXVa presequence was predicted to form an antiparallel β-sheet (8Cumsky M.G. Trueblood C.E. Ko C. Poynton R.O. Mol. Cell Biol. 1987; 7: 3511-3519Crossref PubMed Scopus (58) Google Scholar). Further, not there is no for mitochondria to have to discriminate between precursor not of proteins between chloroplasts and mitochondria in In et al. G. Plant J. PubMed Scopus Google Scholar) have that of the for pea in transgenic plants in the targeting of the enzyme both to chloroplasts and to mitochondria. were also able to show that this targeting was due to the transit it was able to a acetyltransferase protein to both in This is not is found in and the 1990; 180: PubMed Scopus Google Scholar), but it is by a single in the protein the for targeting to Ferrochelatase is the last enzyme of heme biosynthesis, and its has been in both mitochondria and Biochem. J. PubMed Scopus Google Scholar). of a yeast in the we isolated a single for ferrochelatase from Arabidopsis J. Biol. Chem. Full Text PDF PubMed Google Scholar). The precursor protein by the was to targeted to chloroplasts in vitro and to the Furthermore, it was by pea but not by mitochondrial by mitochondrial processing from We that this was the chloroplast of the we isolated an by the same which into two on the of and and G. in and G. in The some was the same as the and was found to by the same The of cDNAs a ferrochelatase with to the ferrochelatase-I we had demonstrated that ferrochelatase-I was targeted to we that was the mitochondrial However, to import the precursor protein into isolated mitochondria were the protein was imported into chloroplasts and to the with an efficiency to that of the ferrochelatase-I precursor Eur. J. Biochem. PubMed Scopus Google Scholar). we had in and found a of ferrochelatase it was that there a of the This to the targeting of In this paper we which that the ferrochelatase-I protein is to both plant mitochondria and chloroplasts in have demonstrated that the precursor for ferrochelatase-I from Arabidopsis is imported into both mitochondria and chloroplasts from in vitro and to the of The import into mitochondria is not due to of the mitochondrial with it was by which the potential for protein import M. Eur. J. Biochem. PubMed Scopus Google Scholar). It also is not due to of by mitochondrial preparation there was no import of the exclusively chloroplast proteins or porphobilinogen Similarly, the pea chloroplasts not proteins that are found exclusively in mitochondria such as or not and also not ferrochelatase-I import into chloroplasts although the precursor to ferrochelatase-I was not in vitro with mitochondrial from J. Biol. Chem. Full Text PDF PubMed Google Scholar), we have been able to with mitochondrial from pea The for this is due to the of used in the two although some evidence of processing was with we observed processing with of pea mitochondrial more was used for the this was able to the precursor to yeast J. Biol. Chem. Full Text PDF PubMed Google Scholar). However, it also the fact that the ferrochelatase-I precursor is from a as is is a the precursor was with of pea mitochondrial protein The of ferrochelatase-I precursor by both chloroplast and mitochondrial was by the of EDTA, indicating that the processing was due to the processing both of which for C. Eur. J. Biochem. PubMed Scopus Google Scholar, J. Knorpp C. Glaser E. Plant Mol. Biol. PubMed Scopus Google Scholar, and G. Schatz G. J. Biol. Chem. Full Text PDF PubMed Google Scholar), which are in C. Plant 1989; PubMed Google protein which has been to targeted to both chloroplasts and mitochondria is from pea G. Plant J. PubMed Scopus Google Scholar). this was in vivo in transgenic it was not possible to the of targeting to the two was it possible to the of to the In the majority of is found in the chloroplasts with in mitochondria and the 1990; 180: PubMed Scopus Google Scholar). Thus that the import into mitochondria is the of This to the for with ferrochelatase-I it was imported with approximately the same efficiency into chloroplasts and mitochondria both from the same pea it were that import into organelle was an it to into the as was for the targeting to yeast mitochondria of passenger proteins to presequence (5Hurt E.C. Soltanifar N. Goldschmidt-Clermont M. Rochaix J.-D. Schatz G. EMBO J. 1986; 5: 1343-1350Crossref PubMed Google Scholar). are no of the of ferrochelatase between mitochondria and but and Biochem. J. PubMed Scopus Google Scholar) found that the specific was very in mitochondria and from and the two isoforms had very of and import efficiency for ferrochelatase by the fact that in chloroplasts there is a Eur. J. Biochem. PubMed Scopus Google direct evidence of targeting of ferrochelatase-I in the of precursor proteins in import in vitro has generally been to the in and there is no this not the for Furthermore, although it was that isoforms of an enzyme in were by as is the for M. of and of in Scholar) and C. PubMed Scopus Google Scholar), of proteins targeted to more are more For example, the mitochondrial and isoforms of Eur. J. Biochem. PubMed Scopus Google Scholar) and and from yeast PubMed Scopus Google Scholar) are each the of a single as are the and mitochondrial of in Arabidopsis Plant Cell. PubMed Scopus Google Scholar). Analysis of in the the of two potential in some the that the same to two has been for pea G. Plant J. PubMed Scopus Google or the for the targeting we have In there is a single protein of in the of to the predicted of the there is a in the the protein from this to a of which in the have implications for the of precursor by mitochondria and it that targeting is recognized by the chloroplast and mitochondrial import it that in vivo there is no that within the cell to targeting of ferrochelatase-I to or another organelle. to exclusively and is not in ferrochelatase-I is the mitochondrial These to ferrochelatase-I import into also that there ferrochelatase In of we have found class which is by such that the it from the the majority of the mitochondrial targeting this was able to a yeast of ferrochelatase was with a a form of yeast ferrochelatase J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The found that in this although there was ferrochelatase this was the membranes of the to the matrix of the mitochondrial which is the of ferrochelatase PubMed Scopus Google Scholar). The of heme synthesized in was with but this was to of the in ferrochelatase is not for heme J. Biol. Chem. 1990; 265: Full Text PDF PubMed Google Scholar). a during an is that this a form of ferrochelatase has been found with the which also of the enzyme of the tetrapyrrole oxidase Biochem. Scopus Google Scholar). The of this is as by the of the which this to Plant PubMed Google M. Biochem. J. 1989; 260: PubMed Scopus Google Scholar). In plants in the are which and cell Chem. Scholar). The of ferrochelatase in cell membranes a to that is and not to In this ferrochelatase have a role to which is also an of the plant to with We have demonstrated that the precursor for ferrochelatase-I from Arabidopsis is imported into both mitochondria and chloroplasts from in vitro and to the of The import into mitochondria is not due to of the mitochondrial with it was by which the potential for protein import M. Eur. J. Biochem. PubMed Scopus Google Scholar). It also is not due to of by mitochondrial preparation there was no import of the exclusively chloroplast proteins or porphobilinogen Similarly, the pea chloroplasts not proteins that are found exclusively in mitochondria such as or not and also not ferrochelatase-I import into chloroplasts In although the precursor to ferrochelatase-I was not in vitro with mitochondrial from J. Biol. Chem. Full Text PDF PubMed Google Scholar), we have been able to with mitochondrial from pea The for this is due to the of used in the two although some evidence of processing was with we observed processing with of pea mitochondrial more was used for the this was able to the precursor to yeast J. Biol. Chem. Full Text PDF PubMed Google Scholar). However, it also the fact that the ferrochelatase-I precursor is from a as is is a the precursor was with of pea mitochondrial protein The of ferrochelatase-I precursor by both chloroplast and mitochondrial was by the of EDTA, indicating that the processing was due to the processing both of which for C. Eur. J. Biochem. PubMed Scopus Google Scholar, J. Knorpp C. Glaser E. Plant Mol. Biol. PubMed Scopus Google Scholar, and G. Schatz G. J. Biol. Chem. Full Text PDF PubMed Google Scholar), which are in C. Plant 1989; PubMed Google Scholar). The protein which has been to targeted to both chloroplasts and mitochondria is from pea G. Plant J. PubMed Scopus Google Scholar). this was in vivo in transgenic it was not possible to the of targeting to the two was it possible to the of to the In the majority of is found in the chloroplasts with in mitochondria and the 1990; 180: PubMed Scopus Google Scholar). Thus that the import into mitochondria is the of This to the for with ferrochelatase-I it was imported with approximately the same efficiency into chloroplasts and mitochondria both from the same pea it were that import into organelle was an it to into the as was for the targeting to yeast mitochondria of passenger proteins to presequence (5Hurt E.C. Soltanifar N. Goldschmidt-Clermont M. Rochaix J.-D. Schatz G. EMBO J. 1986; 5: 1343-1350Crossref PubMed Google Scholar). are no of the of ferrochelatase between mitochondria and but and Biochem. J. PubMed Scopus Google Scholar) found that the specific was very in mitochondria and from and the two isoforms had very of and import efficiency for ferrochelatase by the fact that in chloroplasts there is a Eur. J. Biochem. PubMed Scopus Google Scholar). direct evidence of targeting of ferrochelatase-I in the of precursor proteins in import in vitro has generally been to the in and there is no this not the for Furthermore, although it was that isoforms of an enzyme in were by as is the for M. of and of in Scholar) and C. PubMed Scopus Google Scholar), of proteins targeted to more are more For example, the mitochondrial and isoforms of Eur. J. Biochem. PubMed Scopus Google Scholar) and and from yeast PubMed Scopus Google Scholar) are each the of a single as are the and mitochondrial of in Arabidopsis Plant Cell. PubMed Scopus Google Scholar). Analysis of in the the of two potential in some the that the same to two has been for pea G. Plant J. PubMed Scopus Google Scholar). For or the for the targeting we have In there is a single protein of in the of to the predicted of the there is a in the the protein from this to a of which in the have implications for the of precursor by mitochondria and it that targeting is recognized by the chloroplast and mitochondrial import it that in vivo there is no that within the cell to targeting of ferrochelatase-I to or another organelle. to exclusively and is not in ferrochelatase-I is the mitochondrial These to ferrochelatase-I import into chloroplasts. The also that there ferrochelatase In of we have found class which is by such that the it from the the majority of the mitochondrial targeting this was able to a yeast of ferrochelatase was with a a form of yeast ferrochelatase J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The found that in this although there was ferrochelatase this was the membranes of the to the matrix of the mitochondrial which is the of ferrochelatase PubMed Scopus Google Scholar). The of heme synthesized in was with but this was to of the in ferrochelatase is not for heme J. Biol. Chem. 1990; 265: Full Text PDF PubMed Google Scholar). a during an is that this a form of ferrochelatase has been found with the which also of the enzyme of the tetrapyrrole oxidase Biochem. Scopus Google Scholar). The of this is as by the of the which this to Plant PubMed Google M. Biochem. J. 1989; 260: PubMed Scopus Google Scholar). In plants in the are which and cell Chem. Scholar). The of ferrochelatase in cell membranes a to that is and not to In this ferrochelatase have a role to which is also an of the plant to with We are to of for and for on the J. for on mitochondrial J. C. of for the and C. J. of for