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.
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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.
author list (cited authors)
Xi, J., Ge, Y., Kinsland, C., McLafferty, F. W., & Begley, T. P.
complete list of authors
Xi, J||Ge, Y||Kinsland, C||McLafferty, FW||Begley, TP