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Enzymes of an alternative pathway of glucose metabolism in obligate methanotrophs.

ABSTRACT: Aerobic methanotrophic bacteria utilize methane as a growth substrate but are unable to grow on any sugars. In this study we have shown that two obligate methanotrophs, Methylotuvimicrobium alcaliphilum 20Z and Methylobacter luteus IMV-B-3098, possess functional glucose dehydrogenase (GDH) and gluconate kinase (GntK). The recombinant GDHs from both methanotrophs were homotetrameric and strongly specific for glucose preferring NAD⁺ over NADP⁺. GDH from Mtm. alcaliphilum was most active at pH 10 (V_max = 95 U/mg protein) and demonstrated very high K_m for glucose (91.8 ± 3.8 mM). GDH from Mb. luteus was most active at pH 8.5 (V_max = 43 U/mg protein) and had lower K_m for glucose (16 ± 0.6 mM). The cells of two Mtm. alcaliphilum double mutants with deletions either of the genes encoding GDH and glucokinase (gdh^─/glk^─) or of the genes encoding gluconate kinase and glucokinase (gntk^─/glk^─) had the lower glycogen level and the higher contents of intracellular glucose and trehalose compared to the wild type strain. The gntk^─/glk^─ knockout mutant additionally accumulated gluconic acid. These data, along with bioinformatics analysis, demonstrate that glycogen derived free glucose can enter the Entner-Doudoroff pathway or the pentose phosphate cycle in methanotrophs, bypassing glycolysis via the gluconate shunt.

SUBMITTER: Rozova ON

PROVIDER: S-EPMC8062543 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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Enzymes of an alternative pathway of glucose metabolism in obligate methanotrophs.

Rozova Olga N ON Ekimova Galina A GA Molochkov Nikolai V NV Reshetnikov Alexander S AS Khmelenina Valentina N VN Mustakhimov Ildar I II

Scientific reports 20210422 1

Aerobic methanotrophic bacteria utilize methane as a growth substrate but are unable to grow on any sugars. In this study we have shown that two obligate methanotrophs, Methylotuvimicrobium alcaliphilum 20Z and Methylobacter luteus IMV-B-3098, possess functional glucose dehydrogenase (GDH) and gluconate kinase (GntK). The recombinant GDHs from both methanotrophs were homotetrameric and strongly specific for glucose preferring NAD<sup>+</sup> over NADP<sup>+</sup>. GDH from Mtm. alcaliphilum was ...[more]

PMID: 33888823

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Enzymes of an alternative pathway of glucose metabolism in obligate methanotrophs.

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Enzymes of an alternative pathway of glucose metabolism in obligate methanotrophs.

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