Prophage induction and differential RecA and UmuDAb transcriptome regulation in the DNA damage responses of Acinetobacter baumannii and Acinetobacter baylyi

PLoS One. 2014 Apr 7;9(4):e93861. doi: 10.1371/journal.pone.0093861. eCollection 2014.

Abstract

The SOS response to DNA damage that induces up to 10% of the prokaryotic genome requires RecA action to relieve LexA transcriptional repression. In Acinetobacter species, which lack LexA, the error-prone polymerase accessory UmuDAb is instead required for ddrR induction after DNA damage, suggesting it might be a LexA analog. RNA-Seq experiments defined the DNA damage transcriptome (mitomycin C-induced) of wild type, recA and umuDAb mutant strains of both A. baylyi ADP1 and A. baumannii ATCC 17978. Of the typical SOS response genes, few were differentially regulated in these species; many were repressed or absent. A striking 38.4% of all ADP1 genes, and 11.4% of all 17978 genes, were repressed under these conditions. In A. baylyi ADP1, 66 genes (2.0% of the genome), including a CRISPR/Cas system, were DNA damage-induced, and belonged to four regulons defined by differential use of recA and umuDAb. In A. baumannii ATCC 17978, however, induction of 99% of the 152 mitomycin C-induced genes depended on recA, and only 28 of these genes required umuDAb for their induction. 90% of the induced A. baumannii genes were clustered in three prophage regions, and bacteriophage particles were observed after mitomycin C treatment. These prophages encoded esvI, esvK1, and esvK2, ethanol-stimulated virulence genes previously identified in a Caenorhabditis elegans model, as well as error-prone polymerase alleles. The induction of all 17978 error-prone polymerase alleles, whether prophage-encoded or not, was recA dependent, but only these DNA polymerase V-related genes were de-repressed in the umuDAb mutant in the absence of DNA damage. These results suggest that both species possess a robust and complex DNA damage response involving both recA-dependent and recA-independent regulons, and further demonstrates that although umuDAb has a specialized role in repressing error-prone polymerases, additional regulators likely participate in these species' transcriptional response to DNA damage.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acinetobacter / genetics*
  • Acinetobacter baumannii / genetics*
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • DNA Damage / drug effects
  • DNA Damage / genetics*
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Bacterial / drug effects
  • Gene Expression Regulation, Bacterial / genetics*
  • Mitomycin / pharmacology
  • Rec A Recombinases / genetics*
  • Rec A Recombinases / metabolism
  • Transcriptome / drug effects
  • Transcriptome / genetics*
  • Virus Activation / drug effects
  • Virus Activation / genetics*

Substances

  • Bacterial Proteins
  • DNA-Binding Proteins
  • RecA protein, Acinetobacter calcoaceticus
  • Mitomycin
  • Rec A Recombinases