TY - JOUR
T1 - Reconstitution and Substrate Specificity of the Radical S-Adenosyl-methionine Thiazole C-Methyltransferase in Thiomuracin Biosynthesis
AU - Mahanta, Nilkamal
AU - Zhang, Zhengan
AU - Hudson, Graham A.
AU - Van Der Donk, Wilfred A.
AU - Mitchell, Douglas A.
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/3/29
Y1 - 2017/3/29
N2 - Thiomuracin is a thiopeptide antibiotic with potent activity toward Gram-positive drug-resistant bacteria. Thiomuracin is biosynthesized from a precursor peptide, TbtA, by a complex array of posttranslational modifications. One of several intriguing transformations is the C-methylation of thiazole, occurring at an unactivated sp2 carbon. Herein, we report the in vitro reconstitution of TbtI, the responsible radical S-adenosyl-methionine (rSAM) C-methyltransferase, which catalyzes the formation of 5-methylthiazole at a single site. Our studies demonstrate that a linear hexazole-bearing intermediate of TbtA is a substrate for TbtI whereas macrocyclized thiomuracin GZ is not. In determining the minimal substrate for TbtI, we found that the enzyme is functional when most of the leader peptide has been removed. The in vitro reconstitution of TbtI, a class C rSAM methyltransferase, further adds to the chemical versatility of rSAM enzymes, and informs on the complexity of thiomuracin biosynthesis.
AB - Thiomuracin is a thiopeptide antibiotic with potent activity toward Gram-positive drug-resistant bacteria. Thiomuracin is biosynthesized from a precursor peptide, TbtA, by a complex array of posttranslational modifications. One of several intriguing transformations is the C-methylation of thiazole, occurring at an unactivated sp2 carbon. Herein, we report the in vitro reconstitution of TbtI, the responsible radical S-adenosyl-methionine (rSAM) C-methyltransferase, which catalyzes the formation of 5-methylthiazole at a single site. Our studies demonstrate that a linear hexazole-bearing intermediate of TbtA is a substrate for TbtI whereas macrocyclized thiomuracin GZ is not. In determining the minimal substrate for TbtI, we found that the enzyme is functional when most of the leader peptide has been removed. The in vitro reconstitution of TbtI, a class C rSAM methyltransferase, further adds to the chemical versatility of rSAM enzymes, and informs on the complexity of thiomuracin biosynthesis.
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U2 - 10.1021/jacs.7b00693
DO - 10.1021/jacs.7b00693
M3 - Article
C2 - 28301141
AN - SCOPUS:85016465776
SN - 0002-7863
VL - 139
SP - 4310
EP - 4313
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 12
ER -