RNA-MediatedcisRegulation in Acinetobacter baumannii Modulates Stress-Induced Phenotypic Variation.
In the nosocomial opportunistic pathogenAcinetobacter baumannii, RecA-dependent mutagenesis, which causes antibiotic resistance acquisition, is linked to the DNA damage response (DDR). Notably, unlike theEscherichia coliparadigm,recAand DDR gene expression inA. baumanniiis bimodal. Namely, there is phenotypic variation upon DNA damage, which may provide a bet-hedging strategy for survival. Thus, understandingrecAgene regulation is key to elucidate the yet unknown DDR regulation inA. baumanniiHere, we identify a structured 5' untranslated region (UTR) in therecAtranscript which serves as acis-regulatory element. We show that a predicted stem-loop structure in this 5' UTR affects mRNA half-life and underlies bimodal gene expression and thus phenotypic variation in response to ciprofloxacin treatment. We furthermore show that the stem-loop structure of therecA5' UTR influences intracellular RecA protein levels and,in vivo, impairing the formation of the stem-loop structure of therecA5' UTR lowers cell survival of UV treatment and decreases rifampin resistance acquisition from DNA damage-induced mutagenesis. We hypothesize that the 5' UTR allows for stablerecAtranscripts during stress, including antibiotic treatment, enabling cells to maintain suitable RecA levels for survival. This innovative strategy to regulate the DDR inA. baumanniimay contribute to its success as a pathogen.IMPORTANCEAcinetobacter baumanniiis an opportunistic pathogen quickly gaining antibiotic resistances. Mutagenesis and antibiotic resistance acquisition are linked to the DNA damage response (DDR). However, how the DDR is regulated inA. baumanniiremains unknown, since unlike most bacteria,A. baumanniidoes not follow the regulation of theEscherichia coliparadigm. In this study, we have started to uncover the mechanisms regulating the novelA. baumanniiDDR. We have found that acis-acting 5' UTR regulatesrecAtranscript stability, RecA protein levels, and DNA damage-induced phenotypic variation. Though 5' UTRs are known to provide stability to transcripts in bacteria, this is the first example in which it regulates a bimodal DDR response throughrecAtranscript stabilization, potentially enabling cells to have enough RecA for survival and genetic variability.
Department of Biology, Northeastern University, Boston, Massachusetts, USA.
Carly
C
Ching
Department of Biology, Northeastern University, Boston, Massachusetts, USA.
Kevin
K
Gozzi
Gottfried Wilhelm Leibniz Universität, Hannover, Germany.
Björn
B
Heinemann
Department of Biology, Northeastern University, Boston, Massachusetts, USA.
Yunrong
Y
Chai
Department of Biology, Northeastern University, Boston, Massachusetts, USA v.godoycarter@northeastern.edu.
Veronica G
VG
Godoy
D020121:5' Untranslated Regions; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D010641:Phenotype; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011938:Rec A Recombinases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D013312:Stress, Physiological; D014466:Ultraviolet Rays
D020121:5' Untranslated Regions; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012329:RNA, Bacterial; C089760:RecA protein, Acinetobacter calcoaceticus; D011938:Rec A Recombinases; D012293:Rifampin
Acinetobacter; DNA damage; RecA; gene expression; microbial genetics; molecular biology