Pyruvate Formate-lyase and a Novel Route of Eukaryotic ATP

Pyruvate formate-lyase (PFL) catalyzes thenon-oxidative conver-sion of pyruvate to formate and acetyl-CoA. PFL and its activating enzyme (PFL-AE) are common among strict anaerobic and microaerophilic prokaryotes but are very rare among eukaryotes. In a proteome survey of isolated Chlamydomonas reinhardtii mito-chondria, we found several PFL-specific peptides leading to the identification of cDNAs for PFL and PFL-AE, establishing the exist-ence of a PFL system in this photosynthetic algae. Anaerobiosis and darkness led to increased PFL transcripts but had little effect on protein levels, as determined with antiserum raised against C. rein-hardtii PFL. Protein blots revealed the occurrence of PFL in both chloroplast and mitochondria purified from aerobically grown cells. Mass spectrometry sequencing of C. reinhardtii mitochon-drial proteins, furthermore, identified peptides for phosphotrans-acetylase and acetate kinase. The phosphotransacetylase-acetat