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The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHCII) is the most abundant membrane protein in green plants, and its degradation is a crucial process for the acclimation to high light conditions and for the recovery of nitrogen (N) and carbon (C) during senescence. However, the molecular mechanism of LHCII degradation is largely unknown. Here, we report that chlorophyll b reductase, which catalyzes the first step of chlorophyll b degradation, plays a central role in LHCII degradation. When the genes for chlorophyll b reductases NOL and NYC1 were disrupted in Arabidopsis thaliana, chlorophyll b and LHCII were not degraded during senescence, whereas other pigment complexes completely disappeared. When purified trimeric LHCII was incubated with recombinant chlorophyll b reductase (NOL), expressed in Escherichia coli, the chlorophyll b in LHCII was converted to 7-hydroxymethyl chlorophyll a. Accompanying this conversion, chlorophylls were released from LHCII apoproteins until all the chlorophyll molecules in LHCII dissociated from the complexes. Chlorophyll-depleted LHCII apoproteins did not dissociate into monomeric forms but remained in the trimeric form. Based on these results, we propose the novel hypothesis that chlorophyll b reductase catalyzes the initial step of LHCII degradation, and that trimeric LHCII is a substrate of LHCII degradation. The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHCII) is the most abundant membrane protein in green plants, and its degradation is a crucial process for the acclimation to high light conditions and for the recovery of nitrogen (N) and carbon (C) during senescence. However, the molecular mechanism of LHCII degradation is largely unknown. Here, we report that chlorophyll b reductase, which catalyzes the first step of chlorophyll b degradation, plays a central role in LHCII degradation. When the genes for chlorophyll b reductases NOL and NYC1 were disrupted in Arabidopsis thaliana, chlorophyll b and LHCII were not degraded during senescence, whereas other pigment complexes completely disappeared. When purified trimeric LHCII was incubated with recombinant chlorophyll b reductase (NOL), expressed in Escherichia coli, the chlorophyll b in LHCII was converted to 7-hydroxymethyl chlorophyll a. Accompanying this conversion, chlorophylls were released from LHCII apoproteins until all the chlorophyll molecules in LHCII dissociated from the complexes. Chlorophyll-depleted LHCII apoproteins did not dissociate into monomeric forms but remained in the trimeric form. Based on these results, we propose the novel hypothesis that chlorophyll b reductase catalyzes the initial step of LHCII degradation, and that trimeric LHCII is a substrate of LHCII degradation. Photosynthesis is an indispensable process for plants to generate chemical energy for biological processes. Chlorophyll plays a central role in photosynthesis by harvesting light energy (1Green B.R. Durnford D.G. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1996; 47: 685-714Crossref PubMed Scopus (500) Google Scholar) and driving electron transfer (2Fromme P. Melkozernov A. Jordan P. Krauss N. FEBS Lett. 2003; 555: 40-44Crossref PubMed Scopus (189) Google Scholar). Chlorophyll exists as chlorophyll-protein complexes, which can be divided into two groups (3Barber J. Morris E. Büchel C. Biochim. Biophys. Acta. 2000; 1459: 239-247Crossref PubMed Scopus (60) Google Scholar). One group consists of the core antenna complexes, which include CP43/CP47 of photosystem (PS) 2The abbreviations used are: PSphotosystemHPLChigh-performance liquid chromatographyCP1P700-chlorophyll a-protein complexes of PSILHCIIlight-harvesting chlorophyll a/b-protein complex of photosystem II. II and P700-chlorophyll a-protein complexes of PSI (CP1). The composition and organization of these core antenna complexes is conserved in oxygenic phototrophs. The second group consists of peripheral antenna complexes, which harvest and transfer light energy to the core antenna complexes. Land plants and green algae contain light-harvesting complex II (LHCII) as a peripheral antenna complex (4Liu Z. Yan H. Wang K. Kuang T. Zhang J. Gui L. An X. Chang W. Nature. 2004; 428: 287-292Crossref PubMed Scopus (1414) Google Scholar, 5Jansson S. Trends Plant Sci. 1999; 4: 236-240Abstract Full Text Full Text PDF PubMed Scopus (533) Google Scholar). LHCII is the most abundant pigment-protein complex, binding chlorophyll a and b, which account for >40% of the total chlorophyll (6Consoli E. Croce R. Dunlap D.D. Finzi L. EMBO Rep. 2005; 6: 782-786Crossref PubMed Scopus (36) Google Scholar, 7Tanaka A. Tanaka Y. Tsuji H. Plant Cell Physiol. 1987; 28: 1537-1545Google Scholar). In addition to its light-harvesting function, LHCII regulates energy distribution between PSI and PSII (6Consoli E. Croce R. Dunlap D.D. Finzi L. EMBO Rep. 2005; 6: 782-786Crossref PubMed Scopus (36) Google Scholar), and is involved in the dissipation of excess light energy (8Elrad D. Niyogi K.K. Grossman A.R. Plant Cell. 2002; 14: 1801-1816Crossref PubMed Scopus (172) Google Scholar). It is known that the amount of LHCII varies depending on developmental stages and changes in light environments (9Tanaka A. Melis A. Plant Cell Physiol. 1997; 38: 17-24Crossref Scopus (53) Google Scholar). Taken together, it is considered that the formation and degradation of LHCII are important processes for the survival of plants (10Anderson J.M. Andersson B. Trends Biochem. Sci. 1988; 13: 351-355Abstract Full Text PDF PubMed Scopus (174) Google Scholar). photosystem high-performance liquid chromatography P700-chlorophyll a-protein complexes of PSI light-harvesting chlorophyll a/b-protein complex of photosystem II. LHCII formation has been extensively studied using mutants and transgenic plants of various species. These studies have clarified the close relationship between chlorophyll synthesis and the LHCII formation. LHCII does not accumulate in chlorophyll b-less mutants, probably because LHCII is not stabilized in the thylakoid membranes without chlorophyll b (11Bennett J. Eur. J. Biochem. 1981; 118: 61-70Crossref PubMed Scopus (178) Google Scholar). In contrast, when chlorophyll b synthesis is accelerated by the overexpression of chlorophyllide a oxygenase LHCII increases (12Tanaka A. Ito H. Tanaka R. Tanaka N.K. Yoshida K. Okada K. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 12719-12723Crossref PubMed Scopus (352) Google Scholar), whereas other chlorophyll-protein complexes such as CP43 and CP1 remain constant (13Hirashima M. Satoh S. Tanaka R. Tanaka A. J. Biol. Chem. 2006; 281: 15385-15393Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar). When 5-aminolevulinic acid, a precursor of chlorophyll synthesis, is fed to greening tissues, chlorophyll b accumulation is enhanced and LHCII increases (14Tanaka A. Tanaka Y. Tsuji H. Planta (Heidelberg). 1993; 192: 92-97Google Scholar). LHCII formation might be partly regulated by the expression of Lhc genes, because both Lhc mRNA and LHCII levels increase under low light conditions (15Masuda T. Tanaka A. Melis A. Plant Mol. Biol. 2003; 51: 757-771Crossref PubMed Scopus (103) Google Scholar, 16Tanaka R. Tanaka A. Photosynth. Res. 2005; 85: 327-340Crossref PubMed Scopus (58) Google Scholar), and the reduction of Lhc mRNA levels by antisense mRNA results in the decrease in LHCII (17Andersson J. Wentworth M. Walters R.G. Howard C.A. Ruban A.V. Horton P. Jansson S. Plant J. 2003; 35: 350-361Crossref PubMed Scopus (208) Google Scholar). In vitro reconstitution experiments have clearly shown that the occupation of chlorophyll-binding sites by chlorophyll b is essential for complex stability (18Reinsberg D. Ottmann K. Booth P.J. Paulsen H. J. Mol. Biol. 2001; 308: 59-67Crossref PubMed Scopus (37) Google Scholar, 19Mimuro M. Tanaka A. Photosynth. Res. 2004; 81: 129-137Crossref Scopus (12) Google Scholar), which is consistent with in vivo experiments mentioned as above. In vitro experiments have also unraveled the binding of chlorophyll to the complexes in detail, using time-resolved fluorescence measurement (20Horn R. Paulsen H. J. Biol. Chem. 2004; 279: 44400-44406Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar). In contrast to LHCII formation, its degradation processes are largely unknown. Degradation of LHCII occurs during the reorganization of photosystems and leaf senescence. When low light-grown plants are transferred to high light conditions, LHCII begins to degrade, which results in the formation of small antennae (21Yang D.H. Andersson B. Aro E.M. Ohad I. Photosynth. Res. 2001; 68: 163-174Crossref PubMed Scopus (75) Google Scholar). Likewise when greening tissues are transferred to the dark, LHCII degrades and its chlorophyll is reused for the formation of core antenna complexes, resulting in an increase in the number of PSs of small antenna size (22Tanaka A. Yamamoto Y. Tsuji H. Plant Cell Physiol. 1991; 32: 195-204Crossref Scopus (65) Google Scholar). Furthermore, degradation of LHCII is an essential process of senescence, because LHCII comprises the most abundant membrane proteins (23Chitnis P.R. Thornber J.P. Photosynth. Res. 1988; 16: 41-63Crossref PubMed Scopus (95) Google Scholar), and their nitrogen reserve must be recovered and transported to sink organs. Although the molecular mechanism of LHCII degradation has not been fully elucidated, proteolytic activities against LHCII have been observed in thylakoid membranes. It has been reported that thylakoid membranes from intermittently illuminated bean leaves have high proteolytic activity against LHCII (24Tziveleka L.A. Argyroudi-Akoyunoglou J.H. Plant Physiol. 1998; 117: 961-970Crossref PubMed Scopus (25) Google Scholar), which is consistent with the observation that the LHCII level is low in leaves greened under intermittent illumination. Proteolytic activity against LHCII has also been reported with the reduction in the antenna size of PSII upon acclimation of plants to high light intensities. This proteolytic activity is ATP-dependent, and the protease is thought to be a serine or cysteine protease but not clp or FtsH (25Yang D.H. Webster J. Adam Z. Lindahl M. Andersson B. Plant Physiol. 1998; 118: 827-834Crossref PubMed Scopus (107) Google Scholar). Using a reversed genetic approach, the chloroplast-targeted protease FtsH6 was identified as being responsible for the degradation of LHC during senescence and acclimation to high light conditions (26Zelisko A. García-Lorenzo M. Jansson S. C. Proc. Natl. Acad. Sci. U. S. A. 2005; PubMed Scopus Google Scholar). protease is under high light conditions and be involved in the degradation of LHCII M. R.G. A. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). It has also been reported that the LHCII degrades the and the of LHCII is to be essential for the of the protein by a protease D.H. Paulsen H. Andersson B. FEBS Lett. 2000; PubMed Scopus (60) Google Scholar). these LHCII have not been might in LHCII degradation, as is the in other substrate proteins such as A. N. Adam Z. Plant Cell. 2005; PubMed Scopus Google Scholar, K. Andersson B. I. EMBO J. 2001; PubMed Scopus Google Scholar) and proteins Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar). Degradation of LHCII consists of two is the proteolytic degradation of the protein and the other is chlorophyll degradation. It is chlorophyll degradation the degradation of the protein or protein degradation is the first Chlorophyll b is a pigment of The of chlorophyll b to 7-hydroxymethyl chlorophyll a is the first step of chlorophyll degradation P. N. J. Biol. Chem. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar, W. Photosynth. Res. 2002; PubMed Scopus Google Scholar) and is by chlorophyll b reductase H. T. Tanaka A. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The was M. Ito H. R. S. Y. M. S. Tanaka R. H. M. Tanaka A. Plant Cell. PubMed Scopus Google Scholar). This is in the NYC1 chlorophyll b In this degradation of chlorophyll b is and LHCII is during senescence. has the of protein as the most protein to NYC1 in plants, and the also the as Y. R. S. M. Tanaka A. M. Plant J. PubMed Scopus Google Scholar). These results that chlorophyll b reductase in the initial step of LHCII degradation. an in vitro degradation using LHCII and recombinant chlorophyll b reductase to the molecular mechanism of LHCII degradation. Chlorophyll b in the LHCII was converted to 7-hydroxymethyl chlorophyll a by chlorophyll b chlorophyll to the and all the chlorophyll molecules in LHCII were Based on these we propose an LHCII degradation Arabidopsis was under light in a with a light of the leaf senescence Arabidopsis plants were in for and The mutants, or were from the Arabidopsis and mutants were and the was identified by The of NOL its was by using the is an and is an and into and The expression was into Escherichia of an of the E. was with of and The was until the The expression of the NOL was with for the was by for The were in and disrupted by was a of and the was incubated for It was for to the The recombinant NOL was a with the and The proteins were with the used for of the the recombinant proteins were with and The of the purified NOL was NOL was using an to a protein of when LHCII was used as the substrate of The purified protein was and used of b was from chlorophyll b by with recombinant T. H. K. A. H. T. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar). in of the the was by of of and of The was and for The was with of and chlorophyllide was transferred into of The was using nitrogen b and b were by the of from chlorophyll b and chlorophyllide b, with Chlorophyll b and chlorophyllide b were in of and incubated for the was with of and the b or b was transferred into of The was by with nitrogen leaves of Arabidopsis were with a and The were and for The was in and by for The was in to a chlorophyll of The was incubated with for on and for The was on The were for The LHCII was from the with a and were to the of and and the was a in a and for The was in to a chlorophyll of Chlorophyll in a small amount of and was were to of purified NOL The was incubated for and the was by of for the chlorophyll was to high liquid chromatography as N. Tanaka R. Tanaka A. Plant Cell Physiol. PubMed Scopus Google Scholar). were by Chlorophyll were identified by their on and their LHCII was used as a substrate with various of LHCII and NOL as for LHCII was incubated with NOL in the or of the were to as above. Arabidopsis leaves were with and The was to for and for The proteins in the were by the the LHCII was under the as that were used of the were in and for The were the of a second and was using the to the by the for CP1 and CP43 were against purified and were from complexes of green tissues were as (13Hirashima M. Satoh S. Tanaka R. Tanaka A. J. Biol. Chem. 2006; 281: 15385-15393Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar). leaves were in and for The green was in and for The was in and with the of and and for The green was on the in was a constant of for The LHCII was with when purified LHCII was The chlorophyll of the green were as (13Hirashima M. Satoh S. Tanaka R. Tanaka A. J. Biol. Chem. 2006; 281: 15385-15393Abstract Full Text Full Text PDF PubMed Scopus (72) Google composition of LHCII with Chlorophyll was from the green in and by were by 7-hydroxymethyl chlorophyll chlorophyll and chlorophyll of LHCII with NOL and of LHCII were using an The first step of the of chlorophyll b to chlorophyll a is by chlorophyll b reductase, which chlorophyll b to 7-hydroxymethyl chlorophyll a. and studies identified two chlorophyll b reductase genes, NOL and in the M. Ito H. R. S. Y. M. S. Tanaka R. H. M. Tanaka A. Plant Cell. PubMed Scopus Google Scholar). genes of NOL and NYC1 also in the Arabidopsis an Arabidopsis by and mutants to of these chlorophyll b reductases results in the of LHCII in as observed in with against NYC1 and NOL that these two proteins were completely in the not The and the were under a for and transferred to to senescence. clearly that all chlorophyll molecules in the In the the levels of chlorophyll b were of and the decrease in chlorophyll b level was in the This observation was in contrast to that of the in which chlorophyll b was during Y. R. S. M. Tanaka A. M. Plant J. PubMed Scopus Google Scholar). This might be to the in the NOL expression between and Arabidopsis as in report Y. R. S. M. Tanaka A. M. Plant J. PubMed Scopus Google Scholar). Furthermore, in the of of chlorophyll b was observed This that chlorophyll b reduction by NOL and NYC1 is a a for chlorophyll b degradation. the levels of chlorophyll-binding proteins were by In plants, all chlorophyll-binding apoproteins core and peripheral antenna complexes, during senescence, and these proteins The a degradation to the Degradation of core antenna complexes and was observed in both of the and mutants as in the remained a constant level during to the results of chlorophyll during the was green of green experiments also that LHCII was stabilized in the These results that chlorophyll b reductase plays a central role in LHCII degradation in with that these two chlorophyll b reductases in chlorophyll b degradation in However, chlorophyll b such as chlorophyllide b, b, and b are to in the because of the degradation such as B. J. Sci. 1996; Scopus Google Scholar) and Y. N. T. Plant Physiol. Biochem. 1996; Scholar) have substrate a group the of these was converted to a group by chlorophyll b NOL was expressed in E. coli, and chlorophyll b were incubated with the purified recombinant NOL When chlorophyll b was used as a all chlorophyll b was converted to 7-hydroxymethyl chlorophyll a b was also converted to 7-hydroxymethyl chlorophyllide a both b and b were converted to their molecules and These results that chlorophyll b reductase has substrate and the groups of all the chlorophyll b that in the chlorophyll molecules are to chlorophyll-protein complexes in fully greened chlorophyll b reductase chlorophyll b in the complexes, chlorophyll b by mechanism or degradation of the protein by must the reduction of chlorophyll In contrast, chlorophyll b reduction is the first step of LHCII degradation, chlorophyll b reductase must chlorophyll b in LHCII as a this we in vitro experiments with chlorophyll b reductase and LHCII LHCII which was by was incubated with chlorophyll b reductase, and the were by to chlorophyll a and chlorophyll b were observed to 7-hydroxymethyl chlorophyll a and its the 7-hydroxymethyl chlorophyll a with a decrease in chlorophyll all the chlorophyll b in LHCII was converted to 7-hydroxymethyl chlorophyll a. In contrast, chlorophyll a remained a constant level during the These results clearly that chlorophyll b reductase is to on the substrate the the green of LHCII with chlorophyll b two conditions to the degradation processes of the LHCII In the first LHCII was incubated with a low to the initial process of LHCII degradation was without because chlorophyll b reductase as a When LHCII was incubated with chlorophyll b reductase in the of most of the LHCII as a and levels of chlorophyll and monomeric LHCII were The monomeric LHCII might have been during When was to the monomeric LHCII with a decrease in trimeric The pigment during chlorophylls were from the green on the and by When was in the chlorophyll a and b were in the green whereas other chlorophyll were not with for both and trimeric LHCII a of 7-hydroxymethyl chlorophyll a in addition to chlorophyll a and chlorophyll In contrast, a amount of 7-hydroxymethyl chlorophyll a in pigment These results that chlorophyll b reductase chlorophyll b from trimeric LHCII and converted it to 7-hydroxymethyl chlorophyll a by a of the pigment from the and small amount of 7-hydroxymethyl chlorophyll a was in monomeric When LHCII was incubated with a high green to monomeric and trimeric LHCII and all chlorophyll and molecules as on the we the distribution of LHCII apoproteins on a by with trimeric trimeric LHCII on the was dissociated into by in an the second for clearly that LHCII apoproteins on the in the to the LHCII as as the chlorophyll was not in this These results that LHCII apoproteins in the trimeric when all of their chlorophyll An increase in monomeric LHCII was that the trimeric was when it chlorophyll with the of LHCII both chlorophyll a and chlorophyll It to that the LHCII is when chlorophyll b is released from LHCII during with chlorophyll b These changes also have an on the of other chlorophylls in LHCII during with NOL to the changes of the and a small decrease in the was that a small amount of chlorophyll b been converted to 7-hydroxymethyl chlorophyll a. In contrast, an decrease in of chlorophyll a was observed with a increase in during the first When the was the decrease in until which was consistent with the of chlorophyll b to chlorophyll a The decrease in was It has been reported that between chlorophylls or between chlorophyll and proteins is for T. J. R. Croce R. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). decrease in from the of these to changes of LHCII by the of chlorophyll The of in LHCII degradation has been by in vitro and in vivo thylakoid membranes from high leaves whereas the FtsH6 does not LHCII (26Zelisko A. García-Lorenzo M. Jansson S. C. Proc. Natl. Acad. Sci. U. S. A. 2005; PubMed Scopus Google Scholar). However, the molecular mechanism of LHCII degradation is unknown. It has been reported that LHCII with chlorophyll is in thylakoid membranes with apoproteins D.H. Paulsen H. Andersson B. FEBS Lett. 2000; PubMed Scopus (60) Google Scholar, H. Ito H. Tanaka Y. Tanaka A. Tsuji H. Argyroudi-Akoyunoglou of Scholar), probably because chlorophyll-binding which to the stability of the changes or processes of substrate LHCII might degradation by which was identified as a LHCII to the FtsH a activity C. S. A. C.A. Mol. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar), and by FtsH is used to the from the to the FtsH proteins such as but can be degraded by clp protease C. S. A. C.A. Mol. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). This that the of LHCII by or by other must LHCII degradation by Chlorophyll b reductase this When a small number of chlorophyll b molecules in trimeric LHCII was converted to 7-hydroxymethyl chlorophyll the of chlorophyll a were the of the of the chlorophyll molecules were released from the apoproteins during green when were LHCII apoproteins might not be to chlorophyll a when chlorophyll b by the of chlorophyll b reductase, probably to the of The in thylakoid membranes during of LHCII by chlorophyll b However, it be that chlorophyll molecules to LHCII apoproteins in thylakoid membranes. This chlorophyll b in be converted to 7-hydroxymethyl chlorophyll because studies clearly that chlorophyll b reductase both and chlorophyll the substrate of LHCII have been of the LHCII exists in a trimeric in the thylakoid membranes. Proteolytic activity against LHCII has been with the trimeric The protease degraded both monomeric and trimeric LHCII a or J.H. A. M. R.G. Argyroudi-Akoyunoglou J.H. Biochim. Biophys. Acta. 2002; PubMed Scopus Google Scholar). However, the experiments with LHCII clearly that the monomeric LHCII was by the whereas trimeric LHCII was not D.H. Paulsen H. Andersson B. FEBS Lett. 2000; PubMed Scopus (60) Google Scholar). The hypothesis the of trimeric LHCII into degradation. stability experiments the of the of trimeric LHCII into the monomeric is by biological mechanism such as proteolytic C. S. W. Paulsen H. Biochim. Biophys. Acta. 2006; PubMed Scopus Google Scholar). However, we that trimeric LHCII is by chlorophyll b reductase, and that all the chlorophyll molecules were released from trimeric we trimeric LHCII apoproteins on the which chlorophyll that the trimeric LHCII not dissociate into during of from the Chlorophyll-depleted trimeric apoproteins be degraded by Based on in vivo and in vitro we propose that the LHCII degradation mechanism is as chlorophyll b reductase on LHCII to chlorophyll b from the complexes and it to 7-hydroxymethyl chlorophyll a. Furthermore, 7-hydroxymethyl chlorophyll a is converted to chlorophyll a by 7-hydroxymethyl chlorophyll a all the chlorophyll b in LHCII is released from the by the of chlorophyll b, chlorophyll a also from the LHC LHCII apoproteins are by the of LHCII apoproteins are by such as FtsH and LHCII other LHCII proteins are degraded by the because degradation of these complexes is in the M. Ito H. R. S. Y. M. S. Tanaka R. H. M. Tanaka A. Plant Cell. PubMed Scopus Google Scholar). This be to the core antenna complexes of and complexes, because have chlorophyll b and are degraded during in the as in the Degradation of these complexes must be regulated by a degradation a because the degradation of LHCII and other core complexes are LHCII is whereas other chlorophyll a-protein complexes during the of greening tissues (22Tanaka A. Yamamoto Y. Tsuji H. Plant Cell Physiol. 1991; 32: 195-204Crossref Scopus (65) Google Scholar). It is also to that the chlorophyll degradation process the degradation of the protein protease the initial step of LHCII degradation, chlorophyll molecules which generate and to chlorophyll the degradation S. Annu. Rev. Plant Biol. 2006; PubMed Scopus Google Scholar) or is reused in the formation of other chlorophyll-protein complexes T. Ito H. Tanaka A. Plant Physiol. 1997; PubMed Scopus Google Scholar), the level of LHCII were not degraded in the chlorophyll b reductase, other chlorophyll protein complexes such as CP1 and degraded as in the M. Ito H. R. S. Y. M. S. Tanaka R. H. M. Tanaka A. Plant Cell. PubMed Scopus Google Scholar). These that the of chlorophyll b to 7-hydroxymethyl chlorophyll a plays an essential role in LHCII degradation. It has been reported that LHCII degradation is also in mutants such as J. Plant Cell. PubMed Scopus Google Scholar). is a protein and was thought to be involved in the mechanism of LHC complexes by complexes. However, we have shown that the purified LHCII was into the degradation by NOL without the addition of that chlorophyll b reductase activity does not studies are to the relationship between chlorophyll b reductase and other for
Horie et al. (Thu,) studied this question.