Post-translational modifications of methyl-coenzyme m reductase in methanosarcina acetivorans
type: CreativeWork
description: Methyl-coenzyme M reductase (MCR) catalyzes the last step in methanogenesis and the first step in anaerobic methane oxidation, producing gigatons of methane annually and playing a vital role in the biological methane cycle. This enzyme is found solely in methanogenic and methanotrophic archaea, which are ubiquitous microorganisms inhabiting a variety of anoxic environments. Additionally, MCR contains several unusual post-translationally modified (PTM) amino acids near its active site. Although some of these modifications are widely conserved, others are rarely observed. However, all MCRs characterized to date have at least three post-translationally modified amino acids, suggesting an important role in either the catalysis or the structure of the enzyme’s active site. Although the genes responsible for some of the modifications have been elucidated, the identity of the genes required for the modification of the remaining modified amino acids remain unknown. One of these modifications, 2-methylglutamine was shown to be synthesized by a B12-dependent radical SAM (rSAM) enzyme, designated MgmA. In Chapter 2, we show that two different MgmA homologs are able to methylate MCR in vivo when expressed in Methanosarcina acetivorans, an organism that does not normally possess this PTM. M. acetivorans strains expressing MgmA showed small, but significant, reductions in growth rates and yields on methylotrophic substrates. Structural characterization of the Ni(II) form of Gln-methylated M. acetivorans MCR revealed no significant differences in the protein fold between the modified and unmodified enzyme; however, the purified enzyme contained the heterodisulfide reaction product, as opposed to the free cofactors found in eight prior M. acetivorans MCR structures, suggesting that substrate/product binding is altered in the modified enzyme. In Chapter 3, we determined the MCR modification profiles from Methanobacterium formicicum, Methanomassiliicoccus luminyensis and Methanospiri…
abstract: Methyl-coenzyme M reductase (MCR) catalyzes the last step in methanogenesis and the first step in anaerobic methane oxidation, producing gigatons of methane annually and playing a vital role in the biological methane cycle. This enzyme is found solely in methanogenic and methanotrophic archaea, which are ubiquitous microorganisms inhabiting a variety of anoxic environments. Additionally, MCR contains several unusual post-translationally modified (PTM) amino acids near its active site. Although some of these modifications are widely conserved, others are rarely observed. However, all MCRs characterized to date have at least three post-translationally modified amino acids, suggesting an important role in either the catalysis or the structure of the enzyme’s active site. Although the genes responsible for some of the modifications have been elucidated, the identity of the genes required for the modification of the remaining modified amino acids remain unknown. One of these modifications, 2-methylglutamine was shown to be synthesized by a B12-dependent radical SAM (rSAM) enzyme, designated MgmA. In Chapter 2, we show that two different MgmA homologs are able to methylate MCR in vivo when expressed in Methanosarcina acetivorans, an organism that does not normally possess this PTM. M. acetivorans strains expressing MgmA showed small, but significant, reductions in growth rates and yields on methylotrophic substrates. Structural characterization of the Ni(II) form of Gln-methylated M. acetivorans MCR revealed no significant differences in the protein fold between the modified and unmodified enzyme; however, the purified enzyme contained the heterodisulfide reaction product, as opposed to the free cofactors found in eight prior M. acetivorans MCR structures, suggesting that substrate/product binding is altered in the modified enzyme. In Chapter 3, we determined the MCR modification profiles from Methanobacterium formicicum, Methanomassiliicoccus luminyensis and Methanospiri…
author: Rodriguez Carrero, Roy Joel
language: en
language: eng
keywords: Methyl-coenzyme M Reductase, Methanogenesis, Post-translational Modification, Archaea, Methanosarcina
date published: 2024-11-25
date modified: 2026-07-22T22:25:03Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2142/127363