Metabolic Functions of Microbial Nucleoside Diphosphate Kinases

This article summarizes research from our laboratory on two aspects of the biochemistry ofnucleoside diphosphate kinase from Escherichia coli—first, its interactions with several T4bacteriophage-coded enzymes, as part of a multienzyme complex for deoxyribonucleosidetriphosphate biosynthesis. We identify some of the specific interactions and discuss whetherthe complex is linked physically or functionally with the T4 DNA replicationmachinery, orreplisome. Second, we discuss phenotypes of an E. coli mutant strain carrying a targeteddeletion of ndk, the structural gene for nucleoside diphosphate kinase. How do bacteria lackingthis essential housekeeping enzyme synthesize nucleoside triphosphates? In view of the specificinteractions of nucleoside diphosphate kinase with T4 enzymes of DNA metabolism, howdoes T4 multiply after infection of this host? Finally, the ndk disruption strain has highlybiased nucleoside triphosphate pools, including elevations of the CTP and dCTP pools of7- and 23-fold, respectively. Accompanied by these biased nucleotide pools is a strong mutatorphenotype. What is the biochemical basis for the pool abnormalities and what are the mutagenicmechanisms? We conclude with brief references to related work in other laboratories.