Alternative acetate production pathways in Chlamydomonas reinhardtii during dark anoxia and the dominant role of chloroplasts in fermentative acetate production.
Chlamydomonas reinhardtii insertion mutants disrupted for genes encoding acetate kinases (EC 2.7.2.1) (ACK1 and ACK2) and a phosphate acetyltransferase (EC 2.3.1.8) (PAT2, but not PAT1) were isolated to characterize fermentative acetate production. ACK1 and PAT2 were localized to chloroplasts, while ACK2 and PAT1 were shown to be in mitochondria. Characterization of the mutants showed that PAT2 and ACK1 activity in chloroplasts plays a dominant role (relative to ACK2 and PAT1 in mitochondria) in producing acetate under dark, anoxic conditions and, surprisingly, also suggested that Chlamydomonas has other pathways that generate acetate in the absence of ACK activity. We identified a number of proteins associated with alternative pathways for acetate production that are encoded on the Chlamydomonas genome. Furthermore, we observed that only modest alterations in the accumulation of fermentative products occurred in the ack1, ack2, and ack1 ack2 mutants, which contrasts with the substantial metabolite alterations described in strains devoid of other key fermentation enzymes.
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305 wqyang@stanford.edu.
Wenqiang
http://orcid.org/0000-0001-5600-4076
W
Yang
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305.
Claudia
C
Catalanotti
Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, Colorado 80401.
Sarah
S
D'Adamo
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305 Stanford University, Department of Biology, Stanford, California 94305.
Tyler M
TM
Wittkopp
Clemson University, Department of Genetics and Biochemistry, Clemson, South Carolina 29634.
Cheryl J
CJ
Ingram-Smith
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305.
Luke
L
Mackinder
Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, Colorado 80401.
Tarryn E
TE
Miller
Colorado State University, Proteomics and Metabolomics Facility, Fort Collins, Colorado 80523.
Adam L
AL
Heuberger
Colorado State University, Department of Biology, Fort Collins, Colorado 80523.
Graham
G
Peers
Clemson University, Department of Genetics and Biochemistry, Clemson, South Carolina 29634.
Kerry S
KS
Smith
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305.
Martin C
MC
Jonikas
Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305.
Arthur R
AR
Grossman
Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, Colorado 80401.
Matthew C
MC
Posewitz
D000084:Acetate Kinase / Q000235:genetics / Q000378:metabolism*; D000085:Acetates / Q000378:metabolism*; D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics; D002736:Chloroplasts / Q000378:metabolism*; D005285:Fermentation; D008928:Mitochondria / Q000378:metabolism; D016254:Mutagenesis, Insertional; D010709:Phosphate Acetyltransferase / Q000235:genetics / Q000378:metabolism*
D000085:Acetates; D020418:Algal Proteins; D010709:Phosphate Acetyltransferase; D000084:Acetate Kinase