Substrate-dependent regulation of carbon catabolism in marine sulfate-reducing Desulfobacterium autotrophicum HRM2.
Desulfobacterium autotrophicum HRM2 is a metabolically versatile sulfate-reducing bacterium, capable of heterotrophic (e.g. with organic acids and alcohols) and chemolithoautotrophic growth (with H(2)/CO(2)). It employs the Wood-Ljungdahl pathway for complete oxidation of acetyl-CoA to CO(2) and for CO(2) fixation. Here, we investigated substrate-dependent regulation at different levels of anaerobic carbon catabolism in this bacterium. (a) Whole-cell adaptation studies indicated an inducibleutilization of short-chained alcohols, agreeing with a substrate-specific abundance increase (up to 40-fold) of alcohol dehydrogenase Adh4. Simultaneous utilization of lactate and 1-propanol was paralleled by adh4 expression and Adh4 formation, respectively. (b) Degradation of propionate generally involves methylmalonyl-CoA mutase (Sbm). Expression of sbm was upregulated during growth with 1-propanol, but not with a mixture of lactate and 1-propanol. Correspondingly, propionate was excreted during growth with this substrate mixture. (c) CO dehydrogenase, the key enzyme of the Wood-Ljungdahl pathway, is encoded by several genes (cdhC, cdh1 and cdh2) located at different genomic positions. Expression of all of these genes during heterotrophic and autotrophic growth points to a reversible operation of the Wood-Ljungdahl pathway. In summary, the different regulatory patterns displayed by Db. autotrophicum HRM2 at the tested metabolic levels point to a multi-layered regulatory network.
Amann
Judith
J
Max Planck Institute for Marine Microbiology, Bremen, Germany.
Lange
Daniela
D
Schüler
Margarete
M
Rabus
Ralf
R
D000433:1-Propanol / Q000378:metabolism; D000426:Alcohol Dehydrogenase / Q000096:biosynthesis; D000438:Alcohols / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000096:biosynthesis; D000693:Anaerobiosis; D002244:Carbon / Q000378:metabolism*; D020564:Deltaproteobacteria / Q000378:metabolism / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D019344:Lactic Acid / Q000378:metabolism; D009097:Multienzyme Complexes / Q000096:biosynthesis; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism
D000438:Alcohols; D009097:Multienzyme Complexes; D011422:Propionates; D013431:Sulfates; D019344:Lactic Acid; D002244:Carbon; D000433:1-Propanol; D000426:Alcohol Dehydrogenase; C105552:alcohol dehydrogenase IV; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase