title: CsrA impacts survival of Yersinia enterocolitica by affecting a myriad of physiological activities.
abstract: BACKGROUND
  A previous study identified a Yersinia enterocolitica transposon mutant, GY448, that was unable to export the flagellar type three secretion system (T3SS)-dependent phospholipase, YplA. This strain was also deficient for motility and unable to form colonies on Lauria-Bertani agar medium. Preliminary analysis suggested it carried a mutation in csrA. CsrA in Escherichia coli is an RNA-binding protein that is involved in specific post-transcriptional regulation of a myriad of physiological activities. This study investigated how CsrA affects expression of the flagellar regulatory cascade that controls YplA export and motility. It also explored the effect of csrA mutation on Y. enterocolitica in response to conditions that cue physiological changes important for growth in environments found both in nature and the laboratory.
  
  
  RESULTS
  The precise location of the transposon insertion in GMY448 was mapped within csrA. Genetic complementation restored disruptions in motility and the YplA export phenotype (Yex), which confirmed this mutation disrupted CsrA function. Mutation of csrA affected expression of yplA and flagellar genes involved in flagellar T3SS dependent export and motility by altering expression of the master regulators flhDC. Mutation of csrA also resulted in increased sensitivity of Y. enterocolitica to various osmolytes, temperatures and antibiotics.
  
  
  CONCLUSIONS
  The results of this study reveal unique aspects of how CsrA functions in Y. enterocolitica to control its physiology. This provides perspective on how the Csr system is susceptible to adaptation to particular environments and bacterial lifestyles.
authors.affiliation: Microbiology Graduate Group, University of California, Davis, CA, USA. klegrand@ucdavis.edu.|Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. klegrand@ucdavis.edu.
authors.forename: Karen
authors.initials: K
authors.lastname: LeGrand
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. shane_petersen@bio-rad.com.
authors.forename: Shane
authors.initials: S
authors.lastname: Petersen
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. zhengyan.ln.chn@gmail.com.|College of Food Science, Shenyang Agricultural University, Shenyang, PR China. zhengyan.ln.chn@gmail.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. liu_kang816@hotmail.com.
authors.forename: Kang K
authors.initials: KK
authors.lastname: Liu
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. gozturk@ucdavis.edu.
authors.forename: Gulustan
authors.initials: G
authors.lastname: Ozturk
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. chenjy@cau.edu.cn.|College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China. chenjy@cau.edu.cn.
authors.forename: Jing-Yu
authors.initials: JY
authors.lastname: Chen
authors.affiliation: Microbiology Graduate Group, University of California, Davis, CA, USA. gmyoung@ucdavis.edu.|Department of Food Science and Technology, University of California, Davis, Davis, CA, USA. gmyoung@ucdavis.edu.
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Young
mesh_terms: D005407:Flagella / Q000502:physiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D008124:Locomotion; D050296:Microbial Viability; D001678:Organelle Biogenesis; D021381:Protein Transport; D013312:Stress, Physiological; D014157:Transcription Factors / Q000378:metabolism*; D015008:Yersinia enterocolitica / Q000166:cytology / Q000502:physiology*
chemical_list: D014157:Transcription Factors