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Physiological and transcriptomic response to methyl-coenzyme M reductase limitation in Methanosarcina acetivorans.

Authors :
Chadwick, Grayson L.
Dury, Gavin A.
Nayak, Dipti D.
Source :
Applied & Environmental Microbiology. Jul2024, Vol. 90 Issue 7, p1-14. 14p.
Publication Year :
2024

Abstract

Methyl-coenzyme M reductase (MCR) catalyzes the final step of methanogenesis, the microbial metabolism responsible for nearly all biological methane emissions to the atmosphere. Decades of biochemical and structural research studies have generated detailed insights into MCR function in vitro, yet very little is known about the interplay between MCR and methanogen physiology. For instance, while it is routinely stated that MCR catalyzes the rate-limiting step of methanogenesis, this has not been categorically tested. In this study, to gain a more direct understanding of MCR's control on the growth of Methanosarcina acetivorans, we generate a strain with an inducible mcr operon on the chromosome, allowing for careful control of MCR expression. We show that MCR is not growth rate-limiting in substrate-replete batch cultures. However, through careful titration of MCR expression, growth-limiting state(s) can be obtained. Transcriptomic analysis of M. acetivorans experiencing MCR limitation reveals a global response with hundreds of differentially expressed genes across diverse functional categories. Notably, MCR limitation leads to strong induction of methylsulfide methyltransferases, likely due to insufficient recycling of metabolic intermediates. In addition, the mcr operon is not transcriptionally regulated, i.e., it is constitutively expressed, suggesting that the overabundance of MCR might be beneficial when cells experience nutrient limitation or stressful conditions. Altogether, we show that there is a wide range of cellular MCR concentrations that can sustain optimal growth, suggesting that other factors such as anabolic reactions might be rate-limiting for methanogenic growth. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00992240
Volume :
90
Issue :
7
Database :
Academic Search Index
Journal :
Applied & Environmental Microbiology
Publication Type :
Academic Journal
Accession number :
178984794
Full Text :
https://doi.org/10.1128/aem.02220-23