Pathways of ammonia assimilation in obligate methane utilizers

Methylocella palustris gen. nov., sp. nov., a new methane-oxidizing acidophilic bacterium from peat bogs, representing a novel subtype of serine-pathway methanotrophs.

“…The activities of methanol dehydrogenase (EC 1;1;88;8), phenazine methosulfate-, NAD-and glutathione-dependent formaldehyde dehydrogenases (EC 1;2;1;1), formate dehydrogenase (EC 1;2;1;2), NADH-dehydrogenase, hexulosephosphate synthase, pyrophosphate-dependent 6-phosphofructokinase (EC 2;7;1;90), ATP-dependent 6-phosphofructokinase (EC 2;7;1;11), fructose-1,6-bisphosphate aldolase (EC 4;1;2;13), 6-phosphogluconate dehydratase\2-keto-3-deoxy-6-phosphogluconate aldolase (EC 4;1;2;14), hydroxypyruvate reductase (EC 1;1;1;29), serine-glyoxylate aminotransferase (EC 2;6;1;45), ribulose-1,5-bisphosphate carboxylase\oxygenase (EC 4;1;1;39), phosphoribulokinase (EC 2;7;1;19) isocitrate lyase (EC 1;2;4;1), malate synthase, (EC 4;1;3;2), malate dehydrogenase (EC 1;1;1;37), isocitrate dehydrogenase (EC 1;1;1;42), pyruvate dehydrogenase (EC 1;2;4;1), α-ketoglutarate dehydrogenase (EC 1;2;4;2), glutamate dehydrogenase (EC 1;4;1;2), alanine dehydrogenase (EC 1;4;1;1), glutamate synthase (EC 2;6;1;53) and glutamine synthetase (EC 6;3;1;2) were assayed as described previously (Shishkina & Trotsenko, 1979, 1982. The sMMO activity was measured by using a colorimetric assay with tetrazotized o-dianisidine (Phelps et al, 1992).…”

Nitrogen Metabolism in a New Obligate Methanotroph, 'Methylosinus' Strain 6

“…Aminating or deaminating activities of glutamate dehydrogenase or alanine dehydrogenase were not detected in any cell-free extract (nor were they detected in the pellet obtained after disruption of ammonia-or nitrate-grown cells), while high levels of glutamine synthetase (GS) and glutamate synthase (GOGAT) activities were found in all extracts. This indicated that nitrogen was assimilated in 'Methylosinus' 6 exclusively by way of the GS/GOGAT system, as it apparently is in all Type I1 methanotrophs previously examined (Shishkina & Trotsenko, 1979;Murrell & Dalton, 1983b).…”

“…The observed effects of cations on both the GS transferase and biosynthetic activities in 'Methylosinus' 6 were consistent with the full adenylylation of GS in ammonia-and nitrate-grown cultures and with little or no adenylylation of GS in dinitrogen-grown cultures. Studies on other Type I1 methanotrophs have not given any indication that the enzyme might be adenylylated in these organisms (Shishkina & Trotsenko, 1979;Murrell & Dalton, 1983 b).…”

Purification, localization, properties and regulation of glutamine synthetase from Hyphomicrobium X

“…Although the presence of GS has been reported in methanotrophs (Shishkina & Trotsenko, 1979) and in methylotrophic bacteria (Loginova et al, 1982;Bellion & Bolbot, 1983;Brooke et al, 1987), very little is known about the properties and regulation of this enzyme in methylotrophic bacteria. This paper describes the purification, location and regulation of GS from Hyphomicrobium X.…”