Nitrate respiratory metabolism in an obligately autotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6.
Hydrogenobacter thermophilus strain TK-6 was observed to grow anaerobically on nitrate as an electron acceptor when molecular hydrogen was used as an energy source. Nitrite was detected as the product of a respiratory reaction. 15NO, 15N2O, and 15N2 were detected with Na15NO3 as an electron acceptor. Western immunoblot analysis showed that cell-free extracts from cells grown on nitrate reacted with antibodies against heme cd1-type nitrite reductase from Pseudomonas aeruginosa. The positive bands, which had molecular masses similar to that of the heme cd1-type nitrite reductase, were also stained by heme staining. These results indicate that nitrite reductase of strain TK-6 is a heme cd1-type enzyme. Activity of ATP:citrate lyase, one of the key enzymes of the reductive TCA cycle, was detected in cell-free extract of cells cultivated on nitrate, which indicates that the cycle operates during anaerobic growth.
Department of Biotechnology, University of Tokyo, Japan.
M
M
Suzuki
Z J
ZJ
Cui
M
M
Ishii
Y
Y
Igarashi
D000255:Adenosine Triphosphate / Q000378:metabolism; D000693:Anaerobiosis; D001420:Bacteria, Aerobic / Q000254:growth & development / Q000378:metabolism*; D015153:Blotting, Western; D003580:Cytochromes; D003576:Electron Transport Complex IV / Q000032:analysis; D006418:Heme / Q000032:analysis; D009097:Multienzyme Complexes / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D009572:Nitrite Reductases / Q000032:analysis; D007652:Oxo-Acid-Lyases / Q000378:metabolism
D003580:Cytochromes; D009097:Multienzyme Complexes; D009566:Nitrates; D006418:Heme; D000255:Adenosine Triphosphate; D009572:Nitrite Reductases; C028123:nitrite reductase (NO-forming); D003576:Electron Transport Complex IV; D007652:Oxo-Acid-Lyases; C019909:citrate (pro-3S)-lyase