Occurrence, biochemistry and possible biotechnological application of the 3-hydroxypropionate cycle.
The 3-hydroxypropionate cycle, a pathway for autotrophic carbon dioxide fixation, is reviewed with special emphasis on the biochemistry of CO2 fixing enzymes in Acidianus brierleyi, a thermophilic and acidophilic archeon. In the 3-hydroxypropionate cycle, two enzymes, acetyl-CoA carboxylase and propionyl-CoA carboxylase, catalyze CO2 fixation. It has been shown in A. brierleyi, and subsequently in Metallosphaera sedula, that acetyl-CoA carboxylase is promiscuous, acting equally well on acetyl-CoA and propionyl-CoA. The subunit structure of the acyl-CoA carboxylase was shown to be alpha4beta4gamma4. Gene cloning revealed that the genes encoding the three subunits are adjacent to each other. accC encodes the beta-subunit (59 kDa subunit, biotin carboxylase subunit), accB encodes the gamma-subunit (20 kDa subunit, biotin carboxyl carrier protein), and pccB encodes the alpha-subunit (62 kDa subunit, carboxyltransferase subunit). Sequence analyses showed that accC and accB are co-transcribed and that pccB is transcribed separately. Potential biotechnological applications for the 3-hydroxypropionate cycle are also presented.
Department of Biotechnology, Graduate School of Agricultural and Life Sciences, 1-1-1 Yayoi, Bunkyo-ku, 113-8657, Tokyo, Japan.
M
M
Ishii
S
S
Chuakrut
H
H
Arai
Y
Y
Igarashi
D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D041541:Acidianus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002245:Carbon Dioxide / Q000378:metabolism*; D019344:Lactic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D043586:Methylmalonyl-CoA Decarboxylase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data
D002245:Carbon Dioxide; D019344:Lactic Acid; C031601:hydracrylic acid; D000103:Acetyl-CoA Carboxylase; D043586:Methylmalonyl-CoA Decarboxylase