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The Escherichia coli colibactin resistance protein ClbS is a novel DNA binding protein that protects DNA from

Katja Molan1, Zdravko Podlesek1, Vesna Hodnik1

  • 1Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana, Slovenia.

DNA Repair
|May 27, 2019
PubMed

Insights

The ClbS protein protects bacteria from DNA damage caused by genotoxins like colibactin and Usp nuclease. Its DNA-binding ability may help safeguard bacterial genomes against degradation.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Cells possess mechanisms to maintain genome integrity against damaging agents.
  • The polyketide synthase (pks) island in *Escherichia coli* produces colibactin, a genotoxin linked to colorectal cancer.
  • ClbS, a cyclopropane hydrolase, confers resistance to colibactin by metabolizing its toxic cyclopropane ring.

Purpose of the Study:

  • To investigate the protective role of ClbS against other genotoxins beyond colibactin.
  • To elucidate the mechanism underlying ClbS-mediated protection against DNA damage.
  • To determine the DNA-binding properties of the ClbS protein.

Main Methods:

  • Utilized the *recA::gfp* reporter system to assess DNA damage in *E. coli* exposed to Usp nuclease.
  • Investigated the interaction of purified ClbS protein with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA).
  • Analyzed bacterial viability and growth under genotoxic stress in the presence of ClbS.

Main Results:

  • ClbS conferred resistance and enabled growth of *E. coli* expressing the Usp nuclease, another genotoxin.
  • The *recA::gfp* reporter confirmed that ClbS protects against Usp-induced DNA damage.
  • ClbS directly binds to both ssDNA and dsDNA, with a preference for ssDNA.

Conclusions:

  • ClbS provides protection against DNA damage induced by multiple genotoxins, including Usp nuclease.
  • The DNA-binding capability of ClbS is a key factor in its genome-protective function.
  • ClbS-mediated DNA binding may represent a general bacterial strategy for genome protection against degradation.
Keywords:
ClbSDNA damage protectionDNA-binding proteinEscherichia coliPks genomic island

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