Escherichia coli Rep DNA helicase and error-prone DNA polymerase IV interact physically and functionally

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Escherichia coli DNA polymerase IV (Pol IV), encoded by dinB, is a Y-family polymerase.
• Pol IV synthesizes DNA past lesions and restarts stalled replication forks.
• Pol IV is error-prone, contributing to mutations during DNA damage and stress.

Purpose of the Study:

• To investigate the interaction between E. coli Pol IV and Rep DNA helicase.
• To determine the functional consequences of this interaction on enzyme activities.
• To elucidate the role of Rep in Pol IV-dependent adaptive mutagenesis.

Main Methods:

• In vitro biochemical assays to assess enzyme interactions and activities.
• Analysis of Pol IV β clamp-binding motif involvement.
• In vivo studies in stationary-phase E. coli cells.

Main Results:

• Pol IV and Rep DNA helicase interact in vitro.
• The interaction enhances both Rep's helicase activity and Pol IV's polymerase activity.
• Rep stimulates Pol IV activity independently of its helicase function or DNA-binding ability.
• Rep enhances Pol IV's mutagenic activity in vivo.

Conclusions:

• Rep DNA helicase plays a significant role in Pol IV-dependent adaptive mutation.
• The interaction between Rep and Pol IV offers new insights into controlling Pol IV's mutagenic activity.
• Rep contributes to stress-induced mutagenesis by modulating Pol IV function.