A highly active decarboxylating dehydrogenase with rationally inverted coenzyme specificity

Ridong Chen, Ann Greer, Antony M. Dean

Research output: Contribution to journalArticlepeer-review

94 Scopus citations

Abstract

The isocitrate dehydrogenase of Escherichia coli, which lacks the Rossmann fold common to other dehydrogenases, displays a 7000-fold preference for NADP over NAD (calculated as the ratio of k(cat)/K(m)). Guided by x-ray crystal structures and molecular modeling, site-directed mutagenesis has been used to introduce six substitutions in the adenosine binding pocket that systematically shift coenzyme preference toward NAD. The engineered enzyme displays an 850-fold preference for NAD over NADP, which exceeds the 140- fold preference displayed by a homologous NAD-dependent enzyme. Of the six mutations introduced, only one is identical in all related NAD-dependent enzyme sequences-strict adherence to homology as a criterion for replacing these amino acids impairs function. Two additional mutations at remote sites improve performance further, resulting in a final mutant enzyme with kinetic characteristics and coenzyme preference comparable to naturally occurring homologous NAD-dependent enzymes.

Original languageEnglish (US)
Pages (from-to)11666-11670
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume92
Issue number25
DOIs
StatePublished - Dec 5 1995

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