title: A hydrogenosome with pyruvate formate-lyase: anaerobic chytrid fungi use an alternative route for pyruvate catabolism.
abstract: The chytrid fungi Piromyces sp. E2 and Neocallimastix sp. L2 are obligatory amitochondriate anaerobes that possess hydrogenosomes. Hydrogenosomes are highly specialized organelles engaged in anaerobic carbon metabolism; they generate molecular hydrogen and ATP. Here, we show for the first time that chytrid hydrogenosomes use pyruvate formate-lyase (PFL) and not pyruvate:ferredoxin oxidoreductase (PFO) for pyruvate catabolism, unlike all other hydrogenosomes studied to date. Chytrid PFLs are encoded by a multigene family and are abundantly expressed in Piromyces sp. E2 and Neocallimastix sp. L2. Western blotting after cellular fractionation, proteinase K protection assays and determinations of enzyme activities reveal that PFL is present in the hydrogenosomes of Piromyces sp. E2. The main route of the hydrogenosomal carbon metabolism involves PFL; the formation of equimolar amounts of formate and acetate by isolated hydrogenosomes excludes a significant contribution by PFO. Our data support the assumption that chytrid hydrogenosomes are unique and argue for a polyphyletic origin of these organelles.
authors.affiliation: Department of Microbiology and Evolutionary Biology, Faculty of Science, University of Nijmegen, Toernooiveld, 6525 ED Nijmegen, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Akhmanova
authors.forename: F G
authors.initials: FG
authors.lastname: Voncken
authors.forename: K M
authors.initials: KM
authors.lastname: Hosea
authors.forename: H
authors.initials: H
authors.lastname: Harhangi
authors.forename: J T
authors.initials: JT
authors.lastname: Keltjens
authors.forename: H J
authors.initials: HJ
authors.lastname: op den Camp
authors.forename: G D
authors.initials: GD
authors.lastname: Vogels
authors.forename: J H
authors.initials: JH
authors.lastname: Hackstein
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D018076:DNA, Complementary; D004271:DNA, Fungal; D019286:Endopeptidase K / Q000378:metabolism; D015723:Gene Library; D005800:Genes, Fungal; D006859:Hydrogen / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D005810:Multigene Family; D015388:Organelles / Q000201:enzymology*; D010802:Phylogeny; D020089:Piromyces / Q000201:enzymology* / Q000235:genetics; D019289:Pyruvic Acid / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D018076:DNA, Complementary; D004271:DNA, Fungal; D006859:Hydrogen; D019289:Pyruvic Acid; D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D019286:Endopeptidase K