Key points are not available for this paper at this time.
The anaerobic unsaturated fatty acid synthetic pathway of Escherichia coli requires two specialized proteins, FabA and FabB. However, the fabA and fabB genes are found only in the Gram-negative α- and γ-proteobacteria, and thus other anaerobic bacteria must synthesize these acids using different enzymes. We report that the Gram-positive bacterium Enterococcus faecalis encodes a protein, annotated as FabZ1, that functionally replaces the E. coli FabA protein, although the sequence of this protein aligns much more closely with E. coli FabZ, a protein that plays no specific role in unsaturated fatty acid synthesis. Therefore E. faecalis FabZ1 is a bifunctional dehydratase/isomerase, an enzyme activity heretofore confined to a group of Gram-negative bacteria. The FabZ2 protein is unable to replace the function of E. coli FabZ, although FabZ2, a second E. faecalis FabZ homologue, has this ability. Moreover, an E. faecalis FabF homologue (FabF1) was found to replace the function of E. coli FabB, whereas a second FabF homologue was inactive. From these data it is clear that bacterial fatty acid biosynthetic pathways cannot be deduced solely by sequence comparisons. The anaerobic unsaturated fatty acid synthetic pathway of Escherichia coli requires two specialized proteins, FabA and FabB. However, the fabA and fabB genes are found only in the Gram-negative α- and γ-proteobacteria, and thus other anaerobic bacteria must synthesize these acids using different enzymes. We report that the Gram-positive bacterium Enterococcus faecalis encodes a protein, annotated as FabZ1, that functionally replaces the E. coli FabA protein, although the sequence of this protein aligns much more closely with E. coli FabZ, a protein that plays no specific role in unsaturated fatty acid synthesis. Therefore E. faecalis FabZ1 is a bifunctional dehydratase/isomerase, an enzyme activity heretofore confined to a group of Gram-negative bacteria. The FabZ2 protein is unable to replace the function of E. coli FabZ, although FabZ2, a second E. faecalis FabZ homologue, has this ability. Moreover, an E. faecalis FabF homologue (FabF1) was found to replace the function of E. coli FabB, whereas a second FabF homologue was inactive. From these data it is clear that bacterial fatty acid biosynthetic pathways cannot be deduced solely by sequence comparisons. Escherichia coli provides the paradigm for the dissociated (or type II) fatty acid biosynthetic systems (1Rock C.O. Cronan J.E. Biochim. Biophys. Acta. 1996; 1302: 1-16Crossref PubMed Scopus (291) Google Scholar, 2Magnuson K. Jackowski S. Rock C.O. Cronan Jr., J.E. Microbiol. Rev. 1993; 57: 522-542Crossref PubMed Google Scholar). In type II systems, which are found in most bacteria and plants, the individual synthetic steps are catalyzed by a series of discrete proteins encoded by unique genes (1Rock C.O. Cronan J.E. Biochim. Biophys. Acta. 1996; 1302: 1-16Crossref PubMed Scopus (291) Google Scholar, 2Magnuson K. Jackowski S. Rock C.O. Cronan Jr., J.E. Microbiol. Rev. 1993; 57: 522-542Crossref PubMed Google Scholar). Four reactions are required to complete each round of fatty acid elongation. In some cases, multiple enzymes are available to catalyze a given step, suggesting that these proteins have different substrate specificities and/or physiological functions. The E. coli fabA and fabZ genes encode β-hydroxyacyl-ACP 1The abbreviations used are: ACP, acyl carrier protein; RB, rich broth. dehydratases, enzymes that convert β-hydroxyacyl-ACPs to trans-2 unsaturated acyl-ACPs (3Bloch K. Boyer P.D. The Enzymes. 3rd Ed. Academic Press, New York1971: 441-464Google Scholar, 4Mohan S. Kelly T.M. Eveland S.S. Raetz C.R. Anderson M.S. J. Biol. Chem. 1994; 269: 32896-32903Abstract Full Text PDF PubMed Google Scholar, 5Heath R.J. Rock C.O. J. Biol. Chem. 1995; 270: 26538-26542Abstract Full Text Full Text PDF PubMed Scopus (313) Google Scholar, 6Brock D.J. Kass L.R. Bloch K. J. Biol. Chem. 1967; 242: 4432-4440Abstract Full Text PDF PubMed Google Scholar). The trans-2 unsaturated acyl-ACPs produced are the substrates of enoyl-ACP reductases that catalyze the last step of each fatty acid elongation cycle (5Heath R.J. Rock C.O. J. Biol. Chem. 1995; 270: 26538-26542Abstract Full Text Full Text PDF PubMed Scopus (313) Google Scholar). FabA and FabZ differ in that FabZ catalyzes only the dehydratase reaction (4Mohan S. Kelly T.M. Eveland S.S. Raetz C.R. Anderson M.S. J. Biol. Chem. 1994; 269: 32896-32903Abstract Full Text PDF PubMed Google Scholar), whereas FabA is a bifunctional enzyme that also catalyzes isomerization of trans-2-decenoyl-ACP to cis-3-decenoyl-ACP (3Bloch K. Boyer P.D. The Enzymes. 3rd Ed. Academic Press, New York1971: 441-464Google Scholar, 6Brock D.J. Kass L.R. Bloch K. J. Biol. Chem. 1967; 242: 4432-4440Abstract Full Text PDF PubMed Google Scholar, 7Guerra D.J. Browse J.A. Arch. Biochem. Biophys. 1990; 280: 336-345Crossref PubMed Scopus (19) Google Scholar, 8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar), the key step of the classical anaerobic unsaturated fatty acid biosynthetic pathway (3Bloch K. Boyer P.D. The Enzymes. 3rd Ed. Academic Press, New York1971: 441-464Google Scholar). Unlike the trans-2 double bond, the cis-3 double bond cannot be removed by enoyl-ACP reductase but instead is retained to form the double bonds of the unsaturated fatty acid moieties of the membrane lipids. The fabA gene is essential for growth of E. coli and Pseudomonas aeruginosa as shown by both mutational studies (9Cronan Jr., J.E. Silbert D.F. Wulff D.L. J. Bacteriol. 1972; 112: 206-211Crossref PubMed Google Scholar, 10Silbert D.F. Vagelos P.R. Proc. Natl. Acad. Sci. U. S. A. 1967; 58: 1579-1586Crossref PubMed Scopus (99) Google Scholar, 11Hoang T.T. Schweizer H.P. J. Bacteriol. 1997; 179: 5326-5332Crossref PubMed Google Scholar) and by inhibition with a substrate analogue (3Bloch K. Boyer P.D. The Enzymes. 3rd Ed. Academic Press, New York1971: 441-464Google Scholar, 12Kass L.R. J. Biol. Chem. 1968; 243: 3223-3228Abstract Full Text PDF PubMed Google Scholar). It is clear that unsaturated fatty acid synthesis is the essential physiological role of FabA because loss of FabA activity in vivo specifically blocks the synthesis of unsaturated fatty acids (10Silbert D.F. Vagelos P.R. Proc. Natl. Acad. Sci. U. S. A. 1967; 58: 1579-1586Crossref PubMed Scopus (99) Google Scholar, 12Kass L.R. J. Biol. Chem. 1968; 243: 3223-3228Abstract Full Text PDF PubMed Google Scholar). Moreover, fabA mutant strains grow when supplemented with appropriate unsaturated fatty acids, whereas saturated fatty acids fail to support growth (9Cronan Jr., J.E. Silbert D.F. Wulff D.L. J. Bacteriol. 1972; 112: 206-211Crossref PubMed Google Scholar, 10Silbert D.F. Vagelos P.R. Proc. Natl. Acad. Sci. U. S. A. 1967; 58: 1579-1586Crossref PubMed Scopus (99) Google Scholar). It was thought that all bacteria that synthesize unsaturated fatty acids during anaerobic growth utilize a FabA protein. However, recent bacterial genome sequences show that many organisms lack a recognizable FabA homologue, although anaerobically grown cells of these organisms are known to contain unsaturated fatty acids (for review see Refs. 13Heath R.J. White S.W. Rock C.O. Prog. Lipid Res. 2001; 40: 467-497Crossref PubMed Scopus (293) Google Scholar and 14Campbell J.W. Cronan Jr., J.E. Annu. Rev. Microbiol. 2001; 55: 305-332Crossref PubMed Scopus (416) Google Scholar). Indeed in the extant genome sequences FabA homologues are encoded only in the genomes of α- and γ-proteobacteria. Therefore, there seem to be two possibilities to explain anaerobic unsaturated fatty acid synthesis in those bacteria that lack FabA. The first possibility is that chemistry of the pathway is similar to that of E. coli, but the amino acid sequences of the required proteins are sufficiently different from FabA such that they are not recognized as FabA homologues. The second possibility is that different chemistry is used that involves markedly different proteins. It seems that several anaerobic unsaturated fatty acid biosynthetic pathways may exist because Streptococcus pneumoniae, which lacks a FabA homologue, has an enzyme called FabM that performs the key trans-2 to cis-3 isomerization reaction in vitro (the pathway has not yet been confirmed by mutant studies) (8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar). However, FabM seems specific for streptococci and hence irrelevant to other FabA-lacking organisms that synthesize unsaturates during anaerobic growth. In the latter bacteria it seems possible that a FabA homologue is present, but the gene has been annotated as encoding a different enzyme. For example several bacterial genomes contain two copies of genes annotated as encoding FabZ proteins. E. coli FabZ is a protein having weak homology (28% identical residues) to FabA. This sequence homology plus the location of the fabZ gene in a cluster of genes involved in lipid A biosynthesis was sufficient for Raetz and co-workers (4Mohan S. Kelly T.M. Eveland S.S. Raetz C.R. Anderson M.S. J. Biol. Chem. 1994; 269: 32896-32903Abstract Full Text PDF PubMed Google Scholar) to test whether E. coli FabZ could dehydrate β-hydroxymyristoyl-ACP, a lipid A precursor. This enzyme activity was demonstrated, and thus the FabZ was called β-hydroxymyristoyl-ACP dehydratase (4Mohan S. Kelly T.M. Eveland S.S. Raetz C.R. Anderson M.S. J. Biol. Chem. 1994; 269: 32896-32903Abstract Full Text PDF PubMed Google Scholar). However, FabZ was later shown to dehydrate β-hydroxyacyl-ACPs of all chain lengths tested (15Heath R.J. Rock C.O. J. Biol. Chem. 1996; 271: 27795-27801Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar), and thus, the designation as β-hydroxymyristoyl-ACP dehydratase is a misnomer. If the FabZs of other organisms have same broad chain length specificity as E. coli FabZ (15Heath R.J. Rock C.O. J. Biol. Chem. 1996; 271: 27795-27801Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar), then the presence of a second fabZ gene seems redundant unless the encoded protein performs another function such as introduction of a cis double bond. Therefore, it seemed possible that a class of proteins having much stronger sequence similarity to E. coli FabZ than to E. coli FabA might posses the enzymatic capability of FabA, i.e. the ability to introduce a cis double bond. We report that this is the case in the Gram-positive pathogenic bacterium, Enterococcus faecalis V583, an organism having a fatty acid similar to that of E. coli J. Bacteriol. PubMed Google Scholar, Arch. Microbiol. PubMed Scopus Google Scholar). FabA is not the E. coli enzyme specifically required for unsaturated fatty acid is also essential Jr., J.E. Vagelos P.R. J. Bacteriol. PubMed Google Scholar). A similar has been for aeruginosa T.T. Schweizer H.P. J. Bacteriol. 1997; 179: 5326-5332Crossref PubMed Google Scholar). is Cronan Jr., J.E. J. Bacteriol. PubMed Google Scholar, Cronan Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google Scholar), an enzyme thought to the biosynthetic by FabA the fatty acid synthetic with this FabA and show bacterial genomes J.W. Cronan Jr., J.E. Annu. Rev. Microbiol. 2001; 55: 305-332Crossref PubMed Scopus (416) Google Scholar). in the and other such as E. the fabA and fabB genes are found in T.T. Schweizer H.P. J. Bacteriol. 1997; 179: 5326-5332Crossref PubMed Google Scholar, 14Campbell J.W. Cronan Jr., J.E. Annu. Rev. Microbiol. 2001; 55: 305-332Crossref PubMed Scopus (416) Google Scholar). Therefore, given a protein with FabA that although E. faecalis has no recognizable homologue, the genome encode a protein having We report that of the FabF homologues of E. faecalis has Therefore, the synthesis of unsaturated fatty acids in E. faecalis to be catalyzed by two proteins that have been annotated as having no specific in the introduction of the cis double bond. and E. coli strains and used in this are in Arch. Microbiol. PubMed Scopus Google Scholar) was used as the rich for E. coli growth. The of strains rich 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). with was to of and by the of to of used the and and used of was used of strains and A. Cronan Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google J.W. Cronan Jr., J.E. J. Bacteriol. 2001; PubMed Scopus (99) Google Cronan Jr., J.E. J. Bacteriol. PubMed Google Cronan Jr., J.E. J. Bacteriol. PubMed Google Cronan Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google Jr., J.E. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Cronan Jr., J.E. J. Biol. PubMed Scopus Google coli coli of with grown coli of with grown the Cronan Jr., J.E. Microbiol. PubMed Scopus Google J. J. Bacteriol. 1995; PubMed Scopus Google E. PubMed Scopus Google H. H. Cronan J.E. J. Bacteriol. PubMed Scopus Google of E. faecalis in of E. faecalis in from with and and the and of from as of E. faecalis in of E. faecalis in from as from as from with and the and of from as from as from as was from with and the same of from as was in a and of the E. faecalis and fabZ homologues from the for and plus plus plus and plus The first of each was the and the to introduce the reactions and the the E. faecalis fabZ and homologues to and The gene sequences confirmed by by the of of fatty acid synthesis as by and Rock R.J. Rock C.O. J. Biol. Chem. 1996; 271: Full Text Full Text PDF PubMed Scopus Google Scholar). and in of and was The grown to the and the cells in of and in a The was in a for to was to the to of and the protein was removed by was to the to of and the protein was by The protein was in of and for of the same by the with as the In fatty acid synthesis ACP, and of protein of of in a of when present, was to of The reaction for to to by the of to the for the reactions by the in of the with and by Cronan J.E. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The in and to grown different in the and the fatty acid by as J.W. Cronan Jr., J.E. Annu. Rev. Microbiol. 2001; 55: 305-332Crossref PubMed Scopus (416) Google Scholar). For of fatty acids, of a grown in was of the fatty acid and The grown for and then of was and growth was to for The then The acyl then to which by and by as (10Silbert D.F. Vagelos P.R. Proc. Natl. Acad. Sci. U. S. A. 1967; 58: 1579-1586Crossref PubMed Scopus (99) Google Scholar, 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). of of the of the encoding and E. coli which the gene for the of the The of the gene with as E. Cronan J.E. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The proteins a The and the proteins by The E. faecalis genome encodes two homologues each of FabZ and The FabZ1 protein and identical with E. coli FabA and FabZ, whereas the for FabZ2 are and and FabZ2 identical In each case all FabA are the of 1996; Full Text Full Text PDF PubMed Scopus Google Scholar) and the amino acid that the and of then FabZ1 and identical with E. coli FabA and FabZ, whereas the for FabZ2 are and this key the two E. faecalis proteins have sequence to E. coli FabZ than to E. coli FabA, and thus it was to these proteins as FabZ homologues than FabA homologues. In the case of the E. faecalis FabF proteins both sequences more closely with E. coli FabF than with E. coli FabB. and are identical to E. coli and identical to E. coli FabF coli and FabF are whereas the two E. faecalis FabF proteins are The and genes are and in the same with of J.A. H. R.J. S. S. J. J. J. J. H. PubMed Scopus Google Scholar). of but from the other is a homologue of E. coli a gene to encode an enoyl-ACP The and genes are a cluster of genes that encode homologues of all the proteins known to be required for saturated fatty acid biosynthesis in E. test the of these proteins the fabZ and genes of E. faecalis several different E. coli the which of of the encoded proteins by with the of to the synthesis of encoded proteins that the and genes proteins of and that to the from the deduced protein sequences of FabZ1 FabZ2 and that the of FabZ1 and FabZ2 are identical when for the of the two in similar with not that these genes could be in the (the used those of and which are tested the function of the genes by introduction of several E. coli mutant E. faecalis FabZ1 FabA in and in and genes the to and two E. coli fabA mutant and and the tested for growth in of growth of of was found in of not E. faecalis and to the E. coli fabA it possible that both of these unsaturated fatty acid but that the of unsaturated fatty acids for growth of the test this possibility the a of the fabA mutant that also a in Cronan Jr., J.E. Microbiol. PubMed Scopus Google Scholar). strains grown in a supplemented with a fatty with and then with The and fatty acid moieties to that by which each of the unsaturated from the saturated and from The was to the of the by of unsaturated fatty acids to with the saturated We found that the the unsaturated fatty acids, whereas the the not in a that a in fabA not The of unsaturated fatty acid because of FabZ1 and the enoyl-ACP reductase for trans-2-decenoyl-ACP (8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar). convert trans-2-decenoyl-ACP to and FabZ1 of the isomerization reaction We tested the by the of of a specific of the E. coli enoyl-ACP reductase to the the the of the of unsaturated fatty acids to saturated fatty acids by In to the the to in unsaturated fatty acid synthesis. We to a of that the trans-2-decenoyl-ACP available to FabZ1 sufficient enoyl-ACP reductase activity for growth. We in these although that the that of fabA strains for unsaturated fatty acids Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google Scholar) not We also tested FabZ1 for ability to replace FabA in a fatty acid synthesis from an E. coli fabA mutant of a of a type of E. coli with and in of saturated and unsaturated fatty acids with the latter the the of the loss of enoyl-ACP reductase activity in of trans-2 produced by FabA FabZ, because this substrate cannot be by a However, the cis-3-decenoyl-ACP of FabA is a substrate for and thus with an from The is then by and by FabZ to form which cannot be because of the lack of enoyl-ACP Therefore, FabA activity of the enoyl-ACP step but for only a cycle of fatty acid synthesis. We that E. faecalis FabZ1 show similar ability in of fabA mutant of was of such with of this was specifically of FabZ1, no was in of a In the of the of fabA strains the FabZ1 unsaturated and saturated fatty acids, whereas the of the the FabZ2 the saturated fatty acids with only of unsaturated fatty acids The of E. faecalis that be the enzyme for the step of the fatty acid synthetic cycle and that FabZ1 might lack FabZ test these and the such that the E. faecalis genes from the The then E. coli a in which the fabZ gene been and with a The was in the presence of an the fabZ gene of to of the fabZ of was because of the fabZ gene was from a However, introduction of the E. faecalis is with the fabZ the E. coli fabZ in the of in the presence of an of the Moreover, of this that the fabZ by for Therefore, E. faecalis functionally replace E. coli that growth of in the of (or in the presence of was specific to of the to growth although the sequences of FabZ1 and FabZ2 that both are homologues of E. coli FabZ, only FabZ2 could functionally replace the E. coli protein. E. faecalis FabF E. coli that FabZ1 FabA activity that E. faecalis might also encode a protein functionally to E. coli FabB. The was because it is encoded by the gene of E. faecalis is only a of and this was with the gene of the fabA fabB gene found in those bacteria. We E. faecalis an and tested for of two E. coli fabB mutant fabB are of which in growth. of both strains the in the of unsaturated fatty acid of the fabB The fatty acid of the E. coli fabB the was by H. Cronan J.E. J. Bacteriol. PubMed Scopus Google Scholar) and was found to contain of unsaturated fatty acids with those given by introduction of a encoding E. coli fabB not fatty acid in the mutant not test the specificity of E. faecalis E. coli fabB H. Cronan J.E. J. Bacteriol. PubMed Scopus Google Scholar). This an fabB plus a This be but for the presence of a that encodes the fabB of and growth H. Cronan J.E. J. Bacteriol. PubMed Scopus Google Scholar). the of is with that of the H. fabB and tested whether the fabB could be from the We for strains and and loss of the H. fabB a in the of that E. faecalis could replace that of in weak growth in the of although no growth was in a with might have of The of E. faecalis also tested the and genes for FabF The two and and tested supplemented with this these strains lack the to chain substrates and are unable to grow when the is supplemented with Cronan Jr., J.E. J. Bacteriol. PubMed Google Scholar, Cronan Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google Scholar, S. Rock C.O. J. Biol. Chem. Full Text PDF PubMed Google Scholar). of function growth whereas of FabF function growth only in presence of Cronan Jr., J.E. J. Bacteriol. PubMed Google Scholar, Cronan Jr., J.E. J. Biol. Chem. Full Text PDF PubMed Google Scholar, H. Cronan J.E. J. Bacteriol. PubMed Scopus Google Scholar). from the data of the in the presence of of the fabB In the the in the presence of but to grow in the of of the Therefore E. faecalis E. coli catalyzed all of the elongation reactions required for the synthesis of saturated fatty acids E. faecalis could not replace the function of E. coli in the synthesis of unsaturated fatty with these data of the fabB the of unsaturated fatty acids, whereas a with the only of unsaturated acids that the chain lengths of the saturated acids in vitro found to be and when function not The that the fabB mutant this gene for of We report the first that a Gram-positive bacterium encodes a bifunctional The two other Gram-positive bacteria thus a an (8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, Cronan Jr., J.E. J. Bacteriol. PubMed Google Scholar, J. Bacteriol. PubMed Scopus Google Scholar). The E. faecalis annotated as FabZ1 E. coli FabA and lacks FabZ although it aligns more closely with E. coli FabZ than with E. coli FabA. Therefore, in this organism and the gene encoding a homologue of FabA as a A example is E. faecalis a protein that to be a homologue of E. coli FabF but that has the function of E. coli FabB. It might be that of the known proteins might to be by the presence of key amino acid to in vivo such as those However, in both of the this is not the of E. coli FabA and of the protein to a substrate are available 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). show that the However, all but of these are in E. coli FabZ, which lacks The of FabA, which is in E. coli FabZ, was to be for the different by these enzymes 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). However, both FabZ1 and FabZ2 of E. faecalis have this and hence this cannot explain the presence of The in the E. coli FabZ sequence to E. coli FabA of FabA are in both E. faecalis FabZ1 and FabZ2, which also a function in isomerization for these It seems that the extant group two those that are and those that The lack of proteins having sequences FabA and FabZ seems given that E. faecalis FabZ1 has activity and that FabA replace FabZ in a in vitro fatty acid synthesis (15Heath R.J. Rock C.O. J. Biol. Chem. 1996; 271: 27795-27801Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar). In the case of the of of both and FabF are available as as of each protein to substrate and K. J. Biol. 2001; PubMed Scopus Google Scholar, A. S. PubMed Scopus Google Scholar, A. S. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar, J. K. J. PubMed Scopus Google Scholar, Choi K.H. R.J. White S.W. Rock C.O. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar, Rock C.O. White S.W. J. Bacteriol. PubMed Scopus Google Scholar). However, this of the different in vivo substrate specificities of the two enzymes are not R.J. Rock C.O. 2002; PubMed Scopus Google Scholar, J. K. S. Biochem. PubMed Google Scholar). Therefore, when the cannot for the ability of an organism to known to be essential for growth unsaturated fatty the of the requires such as those that data might not be sufficient to the function of a might also be This was the case with E. faecalis FabZ1, the lack of of an E. coli fabA have that the enzyme was unable to introduce cis double bonds fatty However, of the of the protein in E. coli that FabZ1 was in the introduction of cis double but that the of unsaturates produced unable to support growth. with the of (8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar), it seems clear that the of unsaturates in cells E. faecalis FabZ1 was by for trans-2-decenoyl-ACP FabZ1 and the enoyl-ACP This is the that the of a specific of the E. coli enoyl-ACP reductase to an E. coli fabA E. faecalis FabZ1 in a markedly synthesis of unsaturated to the saturated although also the of fatty acid synthesis hence in growth data not (8Marrakchi H. Choi K.H. Rock C.O. J. Biol. Chem. 2002; 277: 44809-44816Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar) found that of the enoyl-ACP reductase growth of an E. coli fabA S. FabM in the presence of because the S. enoyl-ACP reductase is by the could not this because the enoyl-ACP reductase of E. faecalis is of the From the with it seems clear that FabZ1, FabA (3Bloch K. Boyer P.D. The Enzymes. 3rd Ed. Academic Press, New York1971: 441-464Google Scholar, 6Brock D.J. Kass L.R. Bloch K. J. Biol. Chem. 1967; 242: 4432-4440Abstract Full Text PDF PubMed Google Scholar, 7Guerra D.J. Browse J.A. Arch. Biochem. Biophys. 1990; 280: 336-345Crossref PubMed Scopus (19) Google Scholar), must a of the trans-2-decenoyl-ACP by the dehydratase the E. faecalis and genes must be We the and for and whereas the be from and
Wang et al. (Tue,) studied this question.