Strand-biased cytosine deamination at the replication fork causes cytosine to thymine mutations in Escherichia coli

Ashok S. Bhagwat, Weilong Hao, Jesse P. Townes, Heewook Lee, Haixu Tang, Patricia L. Foster

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The rate of cytosine deamination is much higher in single-stranded DNA (ssDNA) than in double-stranded DNA, and copying the resulting uracils causes C to T mutations. To study this phenomenon, the catalytic domain of APOBEC3G (A3G-CTD), an ssDNA-specific cytosine deaminase, was expressed in an Escherichia coli strain defective in uracil repair (ung mutant), and the mutations that accumulated over thousands of generations were determined by whole-genome sequencing. C:G to T:A transitions dominated, with significantly more cytosines mutated to thymine in the lagging-strand template (LGST) than in the leading-strand template (LDST). This strand bias was present in both repair-defective and repair-proficient cells and was strongest and highly significant in cells expressing A3G-CTD. These results show that the LGST is accessible to cellular cytosine deaminating agents, explains the well-known GC skew in microbial genomes, and suggests the APOBEC3 family of mutators may target the LGST in the human genome.

Original languageEnglish (US)
Pages (from-to)2176-2181
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number8
DOIs
StatePublished - Feb 23 2016
Externally publishedYes

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Strand-biased cytosine deamination at the replication fork causes cytosine to thymine mutations in Escherichia coli'. Together they form a unique fingerprint.

Cite this