Persulfide Formation Mediates Cysteine and Homocysteine Biosynthesis in Methanosarcina acetivorans

Benjamin J. Rauch, John Klimek, Larry David, John J. Perona

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The mechanisms of sulfur uptake and trafficking in methanogens inhabiting sulfidic environments are highly distinctive. In aerobes, sulfur transfers between proteins occur via persulfide relay, but direct evidence for persulfides in methanogens has been lacking. Here, we use mass spectrometry to analyze tryptic peptides of the Methanosarcina acetivorans SepCysS and MA1821 proteins purified anaerobically from methanogen cells. These enzymes insert sulfide into phosphoseryl(Sep)-tRNACys and aspartate semialdehyde, respectively, to form Cys-tRNACys and homocysteine. A high frequency of persulfidation at conserved cysteines of each protein was identified, while the substantial presence of persulfides in peptides from other cellular proteins suggests that this modification plays a general physiological role in the organism. Purified native SepCysS containing persulfide at conserved Cys260 generates Cys-tRNACys in anaerobic single-turnover reactions without exogenously added sulfur, directly linking active-site persulfide formation in vivo with catalytic activity.

Original languageEnglish (US)
Pages (from-to)1051-1061
Number of pages11
JournalBiochemistry
Volume56
Issue number8
DOIs
StatePublished - Feb 28 2017

ASJC Scopus subject areas

  • Biochemistry

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