title: The arginine deiminase system facilitates environmental adaptability of Streptococcus equi ssp. zooepidemicus through pH adjustment.
abstract: The arginine deiminase system (ADS) is a secondary metabolic system found in many different bacterial pathogens and it is often associated with virulence. Here, a systematic study of ADS functions in Streptococcus equi subsp. zooepidemicus (SEZ) was performed. Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions. We constructed arcA and arcD deletion mutants (SEZ ΔarcA and SEZ ΔarcD, respectively) and found that SEZ ΔarcA was unable to metabolize arginine and synthesize ammonia; however, arcD deletion resulted in an initial decrease in arginine consumption and ammonia production, followed by recovery to the levels of wild-type SEZ after 24 h of cultivation. Cell extracts of SEZ ΔarcA showed no arginine deiminase (AD) activity, whereas no difference in AD activity between SEZ ΔarcD and wild-type SEZ was observed. SEZ survival tests demonstrated a significant decrease in survival for SEZ ΔarcA, when compared with wild-type SEZ, under acidic conditions and in epithelial cells. These findings indicate that ADS in SEZ contributes to environmental adaptability via ammonia synthesis to reduce pH stress.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ma
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Huixing
authors.initials: H
authors.lastname: Lin
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China. Electronic address: fhj@njau.edu.cn.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Fan
mesh_terms: D000222:Adaptation, Physiological; D000641:Ammonia / Q000378:metabolism; D001120:Arginine / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D050296:Microbial Viability; D018502:Streptococcus equi / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*
chemical_list: D000641:Ammonia; D001120:Arginine; D006867:Hydrolases; C019723:arginine deiminase
keywords: Acid tolerance; Ammonia; Arginine; Arginine deiminase system; Streptococcus equi ssp. zooepidemicus