Biosynthesis of the thiazole moiety of thiamin in Escherichia coli: identification of an acyldisulfide-linked protein--protein conjugate that is functionally analogous to the ubiquitin/E1 complex.
A covalently linked protein--protein conjugate between ThiF and ThiS thiocarboxylate was found in a partially purified coexpressed ThiF/ThiS protein mixture by using Fourier transform mass spectrometry. The Cys-184 of ThiF and the C terminus of ThiS thiocarboxylate were identified to be involved in the formation of this complex by using both mutagenesis and chemical modification methods. A complementation study of Escherichia coli thiF(-) using thiF(C184S) suggests that this conjugate is an essential intermediate involved in the biosynthesis of the thiazole moiety of thiamin. This ThiF/ThiS conjugate is the first characterized example of a unique acyldisulfide intermediate in a biosynthetic system. This protein conjugate is also an example of an ubiquitin-E1 like protein-protein conjugate in prokaryotes and supports a strong evolutionary link between thiamin biosynthesis and the ubiquitin conjugating system.
Xi
J
J
Department of Chemistry and Chemical Biology, Cornell University, 120 Baker Laboratory, Ithaca, NY 14853, USA.
Ge
Y
Y
Kinsland
C
C
McLafferty
F W
FW
Begley
T P
TP
D000215:Acylation; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D004220:Disulfides; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D008025:Ligases / Q000378:metabolism*; D015394:Molecular Structure; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism; D013835:Thiamine Pyrophosphate / Q000096:biosynthesis* / Q000737:chemistry; D013844:Thiazoles / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D004220:Disulfides; D029968:Escherichia coli Proteins; D013844:Thiazoles; D014452:Ubiquitins; C411655:thiS protein, E coli; D044767:Ubiquitin-Protein Ligases; D009713:Nucleotidyltransferases; C411654:ThiF protein, E coli; D008025:Ligases; D013835:Thiamine Pyrophosphate