Browsing by Author "Keltjens, J. T."

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    A Hydrogenosome with Pyruvate Formate-Lyase: Anaerobic Chytrid Fungi Use an Alternative Route for Pyruvate Catabolism. Mol Microbiol 32:1103-1114
    (Wiley, 1999) Akhmanova, Anna; Voncken, Frank; Hosea, Ken M.; Harhangi, H.; Keltjens, J. T.; Op Den Camp, H. J.; Vogels, G. D.; Hackstein, Johannes H. P.
    The chytrid fungi Piromyces sp. E2 and Neocallimastix sp. L2 are obligatory amitochondriate anaerobes that possesshydrogenosomes.Hydrogenosomes arehighly specialized organelles engaged in anaerobic carbon metabolism; they generate molecular hydrogen and ATP. Here, we show for the ®rst 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 signi®cant contribution by PFO. Our data support the assumption that chytrid hydrogenosomes are unique and argue for a polyphyletic origin of these organelles.