Persulfide Formation Mediates Cysteine and Homocysteine Biosynthesis in Methanosarcina acetivorans.
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)-tRNACysand aspartate semialdehyde, respectively, to form Cys-tRNACysand 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-tRNACysin anaerobic single-turnover reactions without exogenously added sulfur, directly linking active-site persulfide formation in vivo with catalytic activity.
Department of Chemistry, Portland State University , P.O. Box 751, Portland, Oregon 97207, United States.|Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States.
Benjamin J
BJ
Rauch
Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States.
John
J
Klimek
Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States.
Larry
L
David
Department of Chemistry, Portland State University , P.O. Box 751, Portland, Oregon 97207, United States.|Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University , 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239, United States.
John J
0000-0002-2219-3021
JJ
Perona
D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D003545:Cysteine / Q000096:biosynthesis* / Q000737:chemistry*; D006710:Homocysteine / Q000096:biosynthesis* / Q000737:chemistry*; D017020:Methanosarcina / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D013440:Sulfides / Q000737:chemistry*
D010455:Peptides; D013440:Sulfides; C051552:persulfides; D006710:Homocysteine; D000604:Amino Acyl-tRNA Synthetases; D003545:Cysteine