Dataset Information

Acetate and Acetyl-CoA Metabolism of ANME-2 Anaerobic Archaeal Methanotrophs.

ABSTRACT: Acetyl-CoA synthetase (ACS) and acetate ligase (ACD) are widespread among microorganisms, including archaea, and play an important role in their carbon metabolism, although only a few of these enzymes have been characterized. Anaerobic methanotrophs (ANMEs) have been reported to convert methane anaerobically into CO₂, polyhydroxyalkanoate, and acetate. Furthermore, it has been suggested that they might be able to use acetate for anabolism or aceticlastic methanogenesis. To better understand the potential acetate metabolism of ANMEs, we characterized an ACS from ANME-2a as well as an ACS and an ACD from ANME-2d. The conversion of acetate into acetyl-CoA (V_max of 8.4 μmol mg^-1 min^-1 and K_m of 0.7 mM acetate) by the monomeric 73.8-kDa ACS enzyme from ANME-2a was more favorable than the formation of acetate from acetyl-CoA (V_max of 0.4 μmol mg^-1 min^-1 and K_m of 0.2 mM acetyl-CoA). The monomeric 73.4-kDa ACS enzyme from ANME-2d had similar V_max values for both directions (V_max,acetate of 0.9 μmol mg^-1 min^-1 versus V_{max,acetyl-CoA} of 0.3 μmol mg^-1 min^-1). The heterotetrameric ACD enzyme from ANME-2d was active solely in the acetate-producing direction. Batch incubations of an enrichment culture dominated by ANME-2d fed with ¹³C₂-labeled acetate produced 3 μmol of [¹³C]methane in 7 days, suggesting that this anaerobic methanotroph might have the potential to reverse its metabolism and perform aceticlastic methanogenesis using ACS to activate acetate albeit at low rates (2 nmol g [dry weight]^-1 min^-1). Together, these results show that ANMEs may have the potential to use acetate for assimilation as well as to use part of the surplus acetate for methane production. IMPORTANCE Acetyl-CoA plays a key role in carbon metabolism and is found at the junction of many anabolic and catabolic reactions. This work describes the biochemical properties of ACS and ACD enzymes from ANME-2 archaea. This adds to our knowledge of archaeal ACS and ACD enzymes, only a few of which have been characterized to date. Furthermore, we validated the in situ activity of ACS in ANME-2d, showing the conversion of acetate into methane by an enrichment culture dominated by ANME-2d.

SUBMITTER: Ouboter HT

PROVIDER: S-EPMC10304654 | biostudies-literature | 2023 Jun

REPOSITORIES: biostudies-literature

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Acetate and Acetyl-CoA Metabolism of ANME-2 Anaerobic Archaeal Methanotrophs.

Ouboter Heleen T HT Arshad Arslan A Berger Stefanie S Saucedo Sanchez Jesus Gerardo JG Op den Camp Huub J M HJM Jetten Mike S M MSM Welte Cornelia U CU Kurth Julia M JM

Applied and environmental microbiology 20230605 6

Acetyl-CoA synthetase (ACS) and acetate ligase (ACD) are widespread among microorganisms, including archaea, and play an important role in their carbon metabolism, although only a few of these enzymes have been characterized. Anaerobic methanotrophs (ANMEs) have been reported to convert methane anaerobically into CO<sub>2</sub>, polyhydroxyalkanoate, and acetate. Furthermore, it has been suggested that they might be able to use acetate for anabolism or aceticlastic methanogenesis. To better unde ...[more]

PMID: 37272802

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Dataset Information

Acetate and Acetyl-CoA Metabolism of ANME-2 Anaerobic Archaeal Methanotrophs.

Publications

Acetate and Acetyl-CoA Metabolism of ANME-2 Anaerobic Archaeal Methanotrophs.

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