Escherichia coli strains (ndk) lacking nucleoside diphosphate kinase are powerful mutators for base substitutions and frameshifts in mismatch-repair-deficient strains.
Nucleoside diphosphate (NDP) kinase is one of the enzymes that maintains triphosphate pools. Escherichia coli strains (ndk) lacking this enzyme have been shown to be modest base substitution mutators, and two members of the human family of NDP kinases act as tumor suppressors. We show here that in E. coli strains lacking NDP kinase high levels of mispairs are generated, but most of these are corrected by the mismatch-repair system. Double mutants that are ndk mutS, lacking both the NDP kinase and mismatch repair, have levels of base substitutions 15-fold higher and levels of certain frameshifts up to 10-fold higher than those of the respective mutations in mutS strains that are NDP kinase proficient. A sequence analysis of the specificity of base substitution mutations generated in ndk and ndk mutS backgrounds as well as other experiments suggests that NDP kinase deficiency stimulates polymerase errors that lead to A:T --> G:C transitions and that the editing capacity of cells may be affected, leading to additional uncorrected mispairs and to A:T --> T:A transversions.
Miller
Jeffrey H
JH
Department of Microbiology, Immunology, and Molecular Genetics and The Molecular Biology Institute, University of California, Los Angeles, California 90095, USA. jhmiller@mbi.ucla.edu
Funchain
Pauline
P
Clendenin
Wendy
W
Huang
Tiffany
T
Nguyen
Anh
A
Wolff
Erika
E
Yeung
Annie
A
Chiang
Ju-Huei
JH
Garibyan
Lilit
L
Slupska
Malgorzata M
MM
Yang
Hanjing
H
D000483:Alleles; D020137:Base Pair Mismatch; D001483:Base Sequence; D017931:DNA Primers; D004260:DNA Repair / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D016368:Frameshift Mutation; D007763:Lac Operon; D009701:Nucleoside-Diphosphate Kinase / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D009701:Nucleoside-Diphosphate Kinase