The ATP:Co(I)rrinoid Adenosyltransferase (CobA) Enzyme of Salmonella enterica Requires the 2'-OH Group of ATP for Function and Yields Inorganic Triphosphate as Its Reaction Byproduct

Authors

Maris V. Fonseca, University of Wisconsin, Madison
Nicole R. Buan, University of Nebraska-LincolnFollow
Alexander R. Horswill, University of Wisconsin, Madison
Ivan Rayment, University of Wisconsin, MadisonFollow
Jorge C. Escalante-SemerenaFollow

Date of this Version

9-2002

Citation

THE JOURNAL OF BIOLOGICAL CHEMISTRY, Vol. 277, No. 36, Issue of September 6, pp. 33127–33131, 2002

DOI 10.1074/jbc.M203893200

Comments

This is an Open Access article under the CC BY license.

Abstract

The specificity of the ATP:corrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica serovar Typhimurium LT2 for its nucleotide substrate was tested using ATP analogs and alternative nucleotide donors. The enzyme showed broad specificity for the nucleotide base and required the 2’-OH group of the ribosyl moiety of ATP for activity. ³¹P NMR spectroscopy was used to identify inorganic triphosphate (PPP_i) as the byproduct of the reaction catalyzed by the CobA enzyme. Cleavage of triphosphate into pyrophosphate and orthophosphate did not occur, indicating that triphosphate cleavage was not required for release of the adenosylcorrinoid product. Triphosphate was a strong inhibitor of the reaction, with 85% of CobA activity lost when the ATP/PPP_i ratio present in the reaction mixture was 1:2.5.