HFA1 Encoding an Organelle-specific Acetyl-CoA Carboxylase Controls Mitochondrial Fatty Acid Synthesis in Saccharomyces cerevisiae (2004)

The Saccharomyces cerevisiae gene, HFA1, encodes a >250-kDa protein, which is required for mitochondrial function. Hfa1p exhibits 72% overall sequence similarity (54% identity) to ACC1-encoded yeast cytoplasmic acetyl-CoA carboxylase. Nevertheless, HFA1 and ACC1 functions are not overlapping because mutants of the two genes have different phenotypes and do not complement each other. Whereas ACC1 is involved in cytoplasmic fatty acid synthesis, the phenotype of hfa1Δ disruptants resembles that of mitochondrial fatty-acid synthase mutants. They fail to grow on lactate or glycerol, and the mitochondrial cofactor, lipoic acid, is reduced to <10% of its normal cellular concentration. Other than Acc1p, the N-terminal sequence of Hfa1p comprises a canonical mitochondrial targeting signal together with a matrix protease cleavage site. Accordingly, the HFA1-encoded protein was specifically assigned by Western blotting of appropriate cell fractions to the mitochondrial compartment. Removal of the mitochondrial targeting sequence abolished the competence of HFA1 DNA to complement hfal null mutants. Conversely and in contrast to the intact HFA1 sequence, the signal sequence-free HFA1 gene complemented the mutational loss of cytoplasmic acetyl-CoA carboxylase. Expression of HFA1 under the control of the ACC1 promoter restored cellular ACC activity in ACC1-defective yeast mutants to wild type levels. From this finding, it is concluded that HFA1 encodes a specific mitochondrial acetyl-CoA carboxylase providing malonyl-CoA for intraorganellar fatty acid and, in particular, lipoic acid synthesis. The Saccharomyces cerevisiae gene, HFA1, encodes a >250-kDa protein, which is required for mitochondrial function. Hfa1p exhibits 72% overall sequence similarity (54% identity) to ACC1-encoded yeast cytoplasmic acetyl-CoA carboxylase. Nevertheless, HFA1 and ACC1 functions are not overlapping because mutants of the two genes have different phenotypes and do not complement each other. Whereas ACC1 is involved in cytoplasmic fatty acid synthesis, the phenotype of hfa1Δ disruptants resembles that of mitochondrial fatty-acid synthase mutants. They fail to grow on lactate or glycerol, and the mitochondrial cofactor, lipoic acid, is reduced to <10% of its normal cellular concentration. Other than Acc1p, the N-terminal sequence of Hfa1p comprises a canonical mitochondrial targeting signal together with a matrix protease cleavage site. Accordingly, the HFA1-encoded protein was specifically assigned by Western blotting of appropriate cell fractions to the mitochondrial compartment. Removal of the mitochondrial targeting sequence abolished the competence of HFA1 DNA to complement hfal null mutants. Conversely and in contrast to the intact HFA1 sequence, the signal sequence-free HFA1 gene complemented the mutational loss of cytoplasmic acetyl-CoA carboxylase. Expression of HFA1 under the control of the ACC1 promoter restored cellular ACC activity in ACC1-defective yeast mutants to wild type levels. From this finding, it is concluded that HFA1 encodes a specific mitochondrial acetyl-CoA carboxylase providing malonyl-CoA for intraorganellar fatty acid and, in particular, lipoic acid synthesis. Yeast contains two distinct fatty-acid synthases (FAS) 1The abbreviations used are: FAS, fatty-acid synthase; ACC, acetyl-CoA carboxylase; RT, reverse transcriptase. 1The abbreviations used are: FAS, fatty-acid synthase; ACC, acetyl-CoA carboxylase; RT, reverse transcriptase. acting specifically in the cytoplasm and in the mitochondrial matrix, respectively (1Lynen F. Eur. J. Biochem. 1980; 112: 431-442Crossref PubMed Scopus (128) Google Scholar, 2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar). Cytoplasmic FAS is a multifunctional enzyme (type I-FAS) and synthesizes the bulk (>95%) of cellular fatty acids. In contrast, mitochondrial FAS is structurally similar to the non-aggregated FAS enzymes found in most bacteria where each component activity is represented by a distinct protein (type II-FAS) (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar, 3Harington A. Herbert C.J. Tung B. Getz G.S. Slonimski P.P. Mol. Microbiol. 1993; 9: 545-555Crossref PubMed Scopus (57) Google Scholar, 4Schneider R. Brors B. Burger F. Camrath S. Weiss H. Curr. Genet. 1997; 32: 384-388Crossref PubMed Scopus (66) Google Scholar). Both FAS systems are encoded by nuclear genes. Although mutational loss of cytoplasmic FAS gives rise to a fatty acid-requiring phenotype (5Schweizer E. Werkmeister K. Jain M.K. Mol. Cell. Biochem. 1978; 21: 95-107Crossref PubMed Scopus (51) Google Scholar), mutants defective in one of the mitochondrial FAS-encoding genes are fatty acid-prototrophic but fail to grow on non-fermentative media (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar, 3Harington A. Herbert C.J. Tung B. Getz G.S. Slonimski P.P. Mol. Microbiol. 1993; 9: 545-555Crossref PubMed Scopus (57) Google Scholar, 4Schneider R. Brors B. Burger F. Camrath S. Weiss H. Curr. Genet. 1997; 32: 384-388Crossref PubMed Scopus (66) Google Scholar). In accordance with these findings, Brody et al. (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar) and Wada et al. (6Wada H. Shintani D. Ohlrogge J. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1591-1596Crossref PubMed Scopus (173) Google Scholar) working with either yeast or plant systems suggest that a major function of mitochondrial FAS refers to lipoic acid synthesis by providing the octanoylacyl-carrier protein precursor of this cofactor. Because the product spectra of both FAS systems are very similar in vitro (7Rössler H. Rieck C. Delong T. Hoja U. Schweizer E. Mol. Gen. Genomics. 2003; 269: 290-298Crossref PubMed Scopus (45) Google Scholar), it remains to be shown whether, apart from octanoic acid, mitochondrially produced long-chain fatty acids serve a specific function as well. Neither octanoic nor lipoic acid is capable of healing the mitochondrial FAS defect when added to the growth medium (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar, 3Harington A. Herbert C.J. Tung B. Getz G.S. Slonimski P.P. Mol. Microbiol. 1993; 9: 545-555Crossref PubMed Scopus (57) Google Scholar). This suggests that either the uptake or the activation of these acids is impossible for mitochondria or intact yeast cells. In all of the known FAS systems, chain extension depends on malonyl-CoA as a substrate. Thus, carboxylation of acetyl-CoA to malonyl-CoA is a key step of fatty acid synthesis. The respective enzyme, acetyl-CoA carboxylase (ACC), comprises three functional components, i.e. biotin carboxylase, biotincarboxyl-carrier protein, and transcarboxylase (8Lane D.M. Moss J. Polakis S.E. Cell. Regul. 1974; 8: 139-194Google Scholar). Depending on the organism, these components represent either three distinct proteins or they are contained as functional domains within difunctional or trifunctional ACC proteins (9Toh H. Kondo H. Tanabe T. Eur. J. Biochem. 1993; 15: 687-696Crossref Scopus (55) Google Scholar). In yeast, cytoplasmic ACC is a single trifunctional polypeptide of 2233 amino acids and with an approximate molecular mass of 250 kDa (10Mishina M. Kamiryo T. Tanaka A. Fukui S. Numa S. Eur. J. Biochem. 1976; 71: 295-300Crossref PubMed Scopus (26) Google Scholar, 11Al-Feel W. Chirala S.S. Wakil S.J. Proc. Natl. Acad. Sci. U. S. A. 1992; 89: 4534-4538Crossref PubMed Scopus (82) Google Scholar, 12Hasslacher M. Ivessa A.S. Paltauf F. Kohlwein S.D. J. Biol. Chem. 1993; 268: 10946-10952Abstract Full Text PDF PubMed Google Scholar). The ACC-encoding gene has been isolated and was designated as ACC1 and FAS3, respectively (11Al-Feel W. Chirala S.S. Wakil S.J. Proc. Natl. Acad. Sci. U. S. A. 1992; 89: 4534-4538Crossref PubMed Scopus (82) Google Scholar, 12Hasslacher M. Ivessa A.S. Paltauf F. Kohlwein S.D. J. Biol. Chem. 1993; 268: 10946-10952Abstract Full Text PDF PubMed Google Scholar). Unlike fatty-acid synthase mutants, which grow upon fatty acid supplementation, ACC1 disruption is lethal and cannot be compensated by external long-chain fatty acids (12Hasslacher M. Ivessa A.S. Paltauf F. Kohlwein S.D. J. Biol. Chem. 1993; 268: 10946-10952Abstract Full Text PDF PubMed Google Scholar, 13Schneiter R. Hitomi M. Ivessa A.S. Fasch E.V. Kohlwein S.D. Tartakoff A.M. Mol. Cell. Biol. 1996; 16: 7161-7172Crossref PubMed Scopus (148) Google Scholar). This characteristic is commonly attributed to the malonyl-CoA requirement of cellular very long-chain fatty acid biosynthesis. Fatty acid elongation appears to be an essential cellular function not supplementable by exogenous very long-chain fatty acid. Other than ACC1 null mutants, however, ACC1 missense mutants are potentially viable and grow upon fatty acid supplementation. The low level of ACC activity eventually retained in some of these mutants obviously fulfills the limited malonyl-CoA requirement of very long-chain fatty acid synthesis (14Mishina M. Roggenkamp R. Schweizer E. Eur. J. Biochem. 1980; 111: 79-87Crossref PubMed Scopus (32) Google Scholar). These mutants therefore provide valuable tools for biochemical studies. Although Acc1p provides the malonyl-CoA used in cytoplasmic fatty acid synthesis, the origin of this substrate in mitochondrial fatty acid synthesis is unclear. Mitochondrial membranes are unlikely to be permeable for malonyl-CoA. In higher plant mitochondria, malonic acid was suggested to be imported into the organelle with subsequent activation and transacylation to acyl carrier protein (15Gueguen V. Macherel D. Jaquinod M. Douce R. Bourgignon J. J. Biol. Chem. 2000; 275: 5016-5025Abstract Full Text Full Text PDF PubMed Scopus (143) Google Scholar). On the other hand, fatty acid synthesis in plant chloroplasts relies on a specific organellar ACC, which is distinctly different from its cytoplasmic counter-part (16Ohlrogge J.B. Jaworski J.G. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1997; 48: 109-136Crossref PubMed Scopus (512) Google Scholar, 17Alban C. Baldet P. Douce R. Biochem. J. 1994; 300: 557-565Crossref PubMed Scopus (104) Google Scholar, 18Konishi T. Shinohara K. Yamada K. Sasaki Y. Plant Cell Physiol. 1996; 37: 117-122Crossref PubMed Scopus (227) Google Scholar). Similarly, identification of the unassigned yeast reading frame, HFA1, encoding a putative protein with striking similarity in its length and amino acid sequence to cytoplasmic ACC suggested the existence of a second and functionally differentiated acetyl-CoA carboxylase being present in this organism as well (19Kearsey S.E. DNA Seq. 1993; 4: 69-70Crossref PubMed Scopus (8) Google Scholar). For many years, however, the biochemical function of HFA1 remained elusive because hfa1Δ disruptants were, other than acc1 mutants, fatty acid-prototrophic and exhibited no obvious ACC deficiency. Accordingly, the fatty acid-requiring phenotype of ACC1 mutants was not compensated by functional HFA1 DNA (12Hasslacher M. Ivessa A.S. Paltauf F. Kohlwein S.D. J. Biol. Chem. 1993; 268: 10946-10952Abstract Full Text PDF PubMed Google Scholar, 13Schneiter R. Hitomi M. Ivessa A.S. Fasch E.V. Kohlwein S.D. Tartakoff A.M. Mol. Cell. Biol. 1996; 16: 7161-7172Crossref PubMed Scopus (148) Google Scholar). A first clue to the physiological function of HFA1 came from an observation in our laboratory that HFA1 mutants failed to grow on non-fermentable carbon sources. As will be demonstrated in the present study, the HFA1 gene product is located in the mitochondria and the phenotype of HFA1 mutants conforms to that of yeast mitochondrial FAS mutants. For complementation of hfa1 null mutants, the putative mitochondrial targeting sequence of HFA1 proved indispensable. On the other hand, signal-free HFA1 DNA restored cytoplasmic ACC activity in acc1 missense mutants. From these findings, it is concluded that HFA1 encodes a mitochondrial acetyl-CoA carboxylase providing malonyl-CoA for organellar fatty acid biosynthesis. Yeast Strains, Plasmids, and Media—The Saccharomyces cerevisiae strain X2180-1A (R. Mortimer, Yeast Genetic Stock Center, Berkeley, CA) served as a haploid wild type reference. The ACC1-missense mutant acc1-318/45 was from our own collection (14Mishina M. Roggenkamp R. Schweizer E. Eur. J. Biochem. 1980; 111: 79-87Crossref PubMed Scopus (32) Google Scholar) The ACC1/acc1Δ was from The was from and served for disruption of the N-terminal of HFA1 together with its DNA was from S. E. S.E. J. Mol. Gen. Genet. PubMed Scopus Google Scholar). D. S.E. M. S. K. 8: PubMed Scopus Google Scholar) was used for of S. cerevisiae intact was isolated from a yeast gene by complementation For HFA1 the of was into In the was by S. cerevisiae which was by from From the the gene together with its HFA1 was isolated as the gene disruption of PubMed Scopus Google Scholar), the served for disruption of HFA1 DNA in the Thus, the was The haploid HFA1 null mutant was a of The yeast of et al. T. D. PubMed Scopus Google Scholar) served as a of the HFA1 sequence in The was from three different to and to the first in the HFA1 reading In an in with the promoter was by the by and appropriate and into the A second HFA1 was but a HFA1 contained the HFA1 reading in with its promoter sequence and a to was by the of into the of In a of the HFA1 been into the yeast A.M. A. PubMed Scopus Google Scholar). to the HFA1 was from by the of the HFA1 DNA by a from the The was used for the of the ACC1 promoter DNA into the of The DNA comprises the first of the ACC1 reading together with of its used for studies. of the are under HFA1 are in HFA1, or ACC1 DNA are and refers to the first in the HFA1 reading by the or ACC1 promoter are as The in and is in The and into and by from appropriate HFA1 are of HFA1 and ACC1 DNA as well as the conforms to Yeast on medium yeast and competence was on medium lactate or of The fatty requirement of yeast mutants was by from fatty acid with and each of and fatty The or medium used for and and hfa1Δ was as R. S. Schweizer E. Curr. Genet. 1993; PubMed Scopus Google Scholar). of from yeast strain X2180-1A in medium was with as by the fractions with of for from to of was for with of reverse and The contained in a of and of the synthesis to in a of the and of of and extension in an The and HFA1 are in and are of each to The used in this by in of medium and of each of the and fatty acids. the in of the protease A and cell with cell by carboxylase was from the by with The protein was in and ACC activity was in with fatty-acid synthase as by M. Scopus Google Scholar). In the was as of contained of of of of of of yeast fatty-acid and of the ACC The was by of the of was Yeast FAS was as by F. Scopus Google Scholar). HFA1 and the from S. cerevisiae wild type as a HFA1 was by of the HFA1 appropriate it was shown that of the product was on the of reverse transcriptase. From this and from the that product proved to be to it is that than of served as a two different and in with the the of the was to The from the of served as a for a of These to the of the was used in with located the of the and In contrast, the two most and in the the of HFA1 is suggested to be located a and of the first in the HFA1 sequence and This to a of of the in of the HFA1 reading and HFA1 and to of the two HFA1 in the was by the S. cerevisiae gene to the in of the HFA1 disruptants isolated by and both and by growth The mutants proved to be viable on medium and to in a Other than mutants of the ACC1 gene, growth of HFA1 disruptants was of fatty acid when on non-fermentable carbon as glycerol, or HFA1 disruptants exhibited the of and Thus, HFA1 appears to be for functional mitochondria in different non-fermentative carbon growth of HFA1 mutants on lactate was growth on was not abolished and In this HFA1 mutants from yeast mutants defective in one of the chain or synthase they the mutants of mitochondrial fatty acid synthesis the mitochondrial cofactor, lipoic acid (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar). the similarity and mitochondrial mutants of the for lipoic acid As is in cellular lipoic acid was reduced in hfa1Δ This well to the lipoic acid in mitochondrial or mutants (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar, S. C. E. Schweizer E. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). these to the loss of HFA1 hfa1Δ disruptants with the HFA1 and For both the and the haploid used as that the HFA1 DNA of either complemented the phenotype of the HFA1 disruption both in haploid and in the of the not From these findings, it is first that the mutant phenotype is to the loss of HFA1 function. HFA1 was functionally both with its promoter and with the promoter when the was in to an of the first of the HFA1 reading the used for these obviously not a complementation by intact HFA1 DNA not have been acid of wild type and yeast lipoic acid in a of hfa1Δ disruptants by intact but not by HFA1 with the on medium and for on either or as under In Expression of HFA1 and Mitochondrial of phenotype of hfa1Δ mutants suggested that HFA1 mitochondrial function and, encodes a mitochondrial of the amino acid sequence the first in the HFA1 reading of or with cytoplasmic acetyl-CoA carboxylase. obvious mitochondrial signal is contained in this the of the and of HFA1 of the first in this the of a yeast mitochondrial signal within this sequence Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). many and amino this N-terminal of Hfa1p comprises and amino acids. a putative signal cleavage is as by the of and P. Eur. J. Biochem. 1996; PubMed Scopus Google Scholar) the and the subsequent Hfa1p sequence the mitochondrial function of both the of HFA1 and the of its product For this yeast with encoding growth to and the was into cytoplasm and both cell fractions by Western blotting for the of As is from a signal with the mitochondrial but not with the The of the signal to a protein of a molecular mass of A second signal to of this a product of A signal was not with that been with the A of kDa with the cytoplasm of both and control obviously a These together with the phenotype of not that HFA1 is required for mitochondrial function but that its product is specifically to the mitochondrial compartment. of low level of HFA1 in yeast mitochondria together with the of cytoplasmic acetyl-CoA carboxylase Hfa1p both in its and biochemical Hfa1p by these to both HFA1 and its product to the cytoplasmic compartment. the promoter and the putative mitochondrial targeting sequence of HFA1 by the of both In the HFA1 sequence is of its and is to the first of the ACC1 reading and Expression of is by the promoter of ACC1 encoding cytoplasmic acetyl-CoA carboxylase. of to the hfa1Δ it was found that in accordance with the loss of its mitochondrial sequence and in contrast to the HFA1 DNA contained in and the HFA1 sequence the to complement the hfa1Δ null mutant On the other hand, targeting of the HFA1 gene product to the yeast cytoplasm compensated for the loss of ACC function in mutants the was with and the providing to the respective in the in contrast to of the the of the not lethal of the to and, the the encoded HFA1 product was capable of for the loss of ACC1 function. The HFA1 DNA contained in similar to the proved in mutant complementation when to the These suggest that in the cytoplasm of a functionally acetyl-CoA carboxylase is from the HFA1 of cytoplasmic ACC activity in acc1-318/45 mutant upon with HFA1 in ACC HFA1 with ACC1 promoter and in a the by enzyme activity cellular ACC in of and acc1-318/45 mutant cells. is in being viable cellular ACC activity is with however, ACC activity in the mutant is restored to wild type and the in this of acc1-318/45 with acc1 DNA ACC which higher than in the wild type either the of the or the specific activity of the encoded enzymes was different in the ACC1 and HFA1 Thus, both the and in the that HFA1 encodes a protein with ACC on the in this study, it is suggested that yeast mitochondria an acetyl-CoA carboxylase encoded by the nuclear gene, Both biochemical and this Accordingly, in a of et al. A. J. Y. C. R. B. J. A. B. P. C. Proc. Natl. Acad. Sci. U. S. A. 2003; PubMed Scopus Google Scholar), Hfa1p has been by as one of the different proteins present in yeast In to cytoplasmic acetyl-CoA carboxylase mutants fatty acid synthesis in the of the putative mitochondrial carboxylase, mitochondrial fatty acid synthesis. As is known from in this the of cytoplasmic fatty acid synthesis in either FAS or ACC1-defective mutants is by a long-chain fatty acid-requiring In contrast, mutants of mitochondrial fatty acid synthase are lipoic and, that both are with mutants suggested the of Hfa1p as a mitochondrial acetyl-CoA carboxylase. for the ACC activity of Hfa1p was of in the cytoplasm of ACC1-defective yeast mutants. to the cytoplasmic was capable of the acc1 mutational defect and, the the ACC activity of a Hfa1p be demonstrated in Nevertheless, ACC1 and HFA1 functionally the two cannot each other in of one of the genes is complemented by the other. The of the mitochondrial for malonyl-CoA be for this of Acc1p and from its amino acid N-terminal extension and from the of an located Hfa1p exhibits of its length a very sequence similarity to In particular, the three carboxylase i.e. biotin carboxylase, protein, and to of In the similarity Acc1p and Hfa1p is higher than that yeast carboxylase on the one and either one of the two acetyl-CoA carboxylase Acc1p or on the other the N-terminal of the HFA1 reading frame, of suggest that the first of the sequence is not the of From the of this study, that not but of HFA1 of the first The HFA1 was of this The its a sequence of the first A of this length is in this other than the to the first the for both a mitochondrial targeting signal Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar) and a subsequent cleavage P. Eur. J. Biochem. 1996; PubMed Scopus Google Scholar). Both be required for the mitochondrial of cytoplasmic acetyl-CoA carboxylase. These suggest that HFA1 of the canonical and for the of an N-terminal mitochondrial sequence, which is upon the of Hfa1p into the mitochondrial This is by our that for complementation of hfa1Δ mutants, the HFA1 DNA sequence of is This sequence be the was the HFA1 The of in the HFA1 reading was as well as of both the and the respective the HFA1 sequence not Thus, apart from an it remains to be that represent one of the where a is The of ACC1 and HFA1 with the being low be to this Although and, in particular, yeast as an with that a of in and in vitro Eur. J. Biochem. 1996; PubMed Scopus Google Scholar, Mol. Cell. Biol. PubMed Scopus Google Scholar). in yeast, other than when with either or Eur. J. Biochem. 1996; PubMed Scopus Google Scholar, A.M. PubMed Scopus Google Scholar). In with specific in the to be of S. J. 1994; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, 1996; PubMed Scopus Google Scholar). In some of the in systems as or Mol. Cell. Biol. PubMed Scopus Google Scholar) are present within the HFA1 remains to be shown one of together with an appropriate sequence as the in of Hfa1p The of acetyl-CoA in the cell is not to yeast but has been for plant and systems (16Ohlrogge J.B. Jaworski J.G. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1997; 48: 109-136Crossref PubMed Scopus (512) Google Scholar, 17Alban C. Baldet P. Douce R. Biochem. J. 1994; 300: 557-565Crossref PubMed Scopus (104) Google Scholar, M. J. J. Biol. Chem. 1993; 268: Full Text PDF PubMed Google Scholar). In two ACC in the and in the respectively (16Ohlrogge J.B. Jaworski J.G. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1997; 48: 109-136Crossref PubMed Scopus (512) Google Scholar, 17Alban C. Baldet P. Douce R. Biochem. J. 1994; 300: 557-565Crossref PubMed Scopus (104) Google Scholar, 18Konishi T. Shinohara K. Yamada K. Sasaki Y. Plant Cell Physiol. 1996; 37: 117-122Crossref PubMed Scopus (227) Google Scholar). In and in two but ACC are present M. J. J. Biol. Chem. 1993; 268: Full Text PDF PubMed Google Scholar). to ACC of yeast, the enzymes and the ACC of are molecular In contrast, the molecular of depends on the plant and most a ACC in of with one of being encoded by the DNA (16Ohlrogge J.B. Jaworski J.G. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1997; 48: 109-136Crossref PubMed Scopus (512) Google Scholar, 18Konishi T. Shinohara K. Yamada K. Sasaki Y. Plant Cell Physiol. 1996; 37: 117-122Crossref PubMed Scopus (227) Google Scholar). This of ACC to the of ACC with the putative origin of the organelle and well with the of and mitochondrial fatty-acid synthases (2Brody S. Oh C. Hoja U. Schweizer E. FEBS Lett. 1997; 408: 217-220Crossref PubMed Scopus (130) Google Scholar, 3Harington A. Herbert C.J. Tung B. Getz G.S. Slonimski P.P. Mol. Microbiol. 1993; 9: 545-555Crossref PubMed Scopus (57) Google Scholar, 4Schneider R. Brors B. Burger F. Camrath S. Weiss H. Curr. Genet. 1997; 32: 384-388Crossref PubMed Scopus (66) Google Scholar, M. Roggenkamp R. Schweizer E. Eur. J. Biochem. 1980; 111: 79-87Crossref PubMed Scopus (32) Google Scholar). In contrast, the ACC of exhibits the multifunctional of cytoplasmic ACC enzymes T. Shinohara K. Yamada K. Sasaki Y. Plant Cell Physiol. 1996; 37: 117-122Crossref PubMed Scopus (227) Google Scholar). In these the ACC has obviously been and, a of the cytoplasmic to have on organellar to the a similar is for the HFA1-encoded mitochondrial ACC of