Function of coenzyme F420-dependent NADP reductase in methanogenic archaea containing an NADP-dependent alcohol dehydrogenase

• Published in: Archives of microbiology Vol. 168; no. 5; pp. 396 - 402
• Main Authors: BERK, H, THAUER, R. K
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.11.1997; Berlin
• Subjects: Alcohol Oxidoreductases - metabolism; Amino Acid Sequence; Bacteriology; Biological and medical sciences; Euryarchaeota - enzymology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Kinetics; Metabolism. Enzymes; Microbiology; Models, Chemical; Molecular Sequence Data; Molecular Weight; NADH, NADPH Oxidoreductases - chemistry; NADH, NADPH Oxidoreductases - isolation & purification; NADH, NADPH Oxidoreductases - metabolism; NADP - metabolism; Oxidoreductases Acting on CH-NH Group Donors - metabolism; Pterins - metabolism; Riboflavin - analogs & derivatives; Riboflavin - metabolism; Sequence Analysis; Methanomicrobiaceae; Archaeobacteria; Enzyme; ); Methanomicrobiales; Characterization; Methanobacterium; Methanobacteriaceae; Methanogenium; Bacteria; Alcohol dehydrogenase (NADP; Methanoculleus; Oxidoreductases; Methanobacteriales; Reductase
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s002030050514

Methanogenic archaea growing on ethanol or isopropanol as the electron donor for CO2 reduction to CH4 contain either an NADP-dependent or a coenzyme F420-dependent alcohol dehydrogenase. We report here that in both groups of methanogens, the N5, N10-methylenetetrahydromethanopterin dehydrogenase and the N5, N10-methylenetetrahydromethanopterin reductase, two enzymes involved in CO2 reduction to CH4, are specific for F420. This raised the question how F420H2 is regenerated in the methanogens with an NADP-dependent alcohol dehydrogenase. We found that these organisms contain catabolic activities of an enzyme catalyzing the reduction of F420 with NADPH. The F420-dependent NADP reductase from Methanogenium organophilum was purified and characterized. The N-terminal amino acid sequence showed 42% sequence identity to a putative gene product in Methanococcus jannaschii, the total genome of which has recently been sequenced.