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. Baun, University of Nebraska-LincolnFollow
Alexander R. Horswill, University of Wisconsin, Madison
Ivan Rayment, University of Wisconsin, Madison
Jorge C. Escalante-Semerena, University of Wisconsin, Madison

Date of this Version

2002

Citation

The Journal of Biological Chemistry, Vol. 277, No. 36, Issue of September 6, pp. 33127–33131, 2002

Comments

Copyright 2002 by The American Society for Biochemistry and Molecular Biology, Inc.

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.