RRC ID 27290
著者 Tsuji Y, Suzuki I, Shiraiwa Y.
タイトル Enzymological evidence for the function of a plastid-located pyruvate carboxylase in the Haptophyte alga Emiliania huxleyi: a novel pathway for the production of C4 compounds.
ジャーナル Plant Cell Physiol
Abstract Pyruvate carboxylase (PYC) catalyzes the β-carboxylation of pyruvate to yield oxaloacetate (OAA). We previously isolated a cDNA encoding a putative PYC (EhPYC1) from the haptophyte alga Emiliania huxleyi and then proposed that EhPYC1 contributes to active anaplerotic β-carboxylation during photosynthesis although PYC activity was not detected in the cell extracts. Involvement of PYC in photosynthetic carbon metabolism is unique, since PYC generally functions in non-photosynthetic organisms. In the present study, we demonstrate that EhPYC1 is highly sensitive to endogenous proteases and therefore is easily degraded in cell extracts. By avoiding proteolytic degradation, PYC activity can be detected in the cell extracts of E. huxleyi. The activity of a recombinant His-tagged EhPYC1 expressed in Streptomyces lividans was inhibited by l-malate in a mixed non-competitive manner. Immunofluorescence labeling showed that EhPYC1 is located in the plastid. This result agrees with the prediction that a bipartite plastid-targeting signal is present that functions to deliver proteins into the four-membrane plastid of haptophyte algae. This is the first finding of a plastid-located PYC. These results indicate that E. huxleyi possesses a unique pathway to produce OAA catalyzed by PYC, and the pathway may provide carbon skeletons for amino acid biosynthesis in the plastid. A database search indicates that PYC genes are widespread in green algae, diatoms and brown algae, suggesting the crucial role of PYC in various aquatic phototrophs.
巻・号 53(6)
ページ 1043-52
公開日 2012-6-1
DOI 10.1093/pcp/pcs045
PII pcs045
PMID 22492231
MeSH Algal Proteins / genetics Algal Proteins / metabolism* Amino Acid Sequence Aspartic Acid / pharmacology Avidin Carbon / metabolism Chloroplast Proteins / genetics Chloroplast Proteins / metabolism Enzyme Activation Genes, Plant Haptophyta / enzymology* Haptophyta / genetics Intracellular Membranes / metabolism Light Malates / pharmacology Mitochondria / genetics Mitochondria / metabolism Oxaloacetic Acid / metabolism Photosynthesis Plastids / enzymology* Plastids / genetics Protein Transport Proteolysis Pyruvate Carboxylase / antagonists & inhibitors Pyruvate Carboxylase / genetics Pyruvate Carboxylase / metabolism* Recombinant Proteins / genetics Recombinant Proteins / metabolism Signal Transduction Streptomyces lividans / genetics Streptomyces lividans / metabolism
IF 4.062
引用数 12
WOS 分野 PLANT SCIENCES CELL BIOLOGY
リソース情報
藻類 NIES-837