title: Proteomic analysis of Streptomyces coelicolor in response to Ciprofloxacin challenge.
abstract: Multi-drug tolerance is an important phenotypic property that complicates treatment of infectious diseases and reshapes drug discovery. Hence a systematic study of the origins and mechanisms of resistance shown by microorganisms is imperative. Since soil-dwelling bacteria are constantly challenged with a myriad of antibiotics, they are potential reservoirs of resistance determinants that can be mobilized into pathogens over a period of time. Elucidating the resistance mechanisms in such bacteria could help future antibiotic discoveries. This research is a preliminary study conducted to determine the effects of ciprofloxacin (CIP) on the intrinsically resistant Gram-positive soil bacterium Streptomyces coelicolor. The effect was investigated by performing 2-DE on total protein extracts of cells exposed to sub-lethal concentrations of ciprofloxacin as compared to the controls. Protein identification by MALDI-TOF/TOF revealed 24 unique differentially expressed proteins, which were statistically significant. The down-regulation of proteins involved in carbohydrate metabolism indicated a shift in the cell physiology towards a state of metabolic shutdown. Furthermore, the observed decline in protein levels involved in transcription and translation machinery, along with depletion of enzymes involved in amino acid biosynthesis and protein folding could be a cellular response to DNA damage caused by CIP, thereby minimizing the effect of defective and energetically wasteful metabolic processes. This could be crucial for the initial survival of the cells before gene level changes could come into play to ensure survival under prolonged adverse conditions. These results are a first attempt towards profiling the proteome of S. coelicolor in response to antibiotic stress. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.
  
  
  CONCLUSIONS
  Soil-dwelling bacteria could serve as a reservoir of resistance determinants for clinically important bacteria. In this work, we investigated, for the first time, the differential proteomic profile of S. coelicolor cells in response to sub-inhibitory concentrations of Ciprofloxacin using 2-DE. Results indicate a shift in the cell physiology towards a state of metabolic shutdown, possibly to counter the DNA damage by ciprofloxacin. Further, up-regulation of GAPDH, RNA pol mRNA and Translation IF2 protein indicates a reprogramming of the cell for long-term survival. This study could serve as a basis for further investigations to elucidate the general mechanism by which soil bacteria exhibit resistance to fluroquinolones. This may help in developing new drug protocols and inventing novel drugs to counter resistance to this class of antibiotics in pathogenic bacteria.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Aishwarya Anand
authors.initials: AA
authors.lastname: Rao
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Minal
authors.initials: M
authors.lastname: Patkari
authors.affiliation: Wadhwani Research Center for Biosciences and Bioengineering, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Panga Jaipal
authors.initials: PJ
authors.lastname: Reddy
authors.affiliation: Wadhwani Research Center for Biosciences and Bioengineering, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Rajneesh
authors.initials: R
authors.lastname: Srivastava
authors.affiliation: Proteomics Lab, National Centre for Cell Science, Ganeshkhind, Pune 411007, Maharashtra, India.
authors.forename: Namita
authors.initials: N
authors.lastname: Pendharkar
authors.affiliation: Proteomics Lab, National Centre for Cell Science, Ganeshkhind, Pune 411007, Maharashtra, India.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Rapole
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. Electronic address: sarikam@iitb.ac.in.
authors.forename: Sarika
authors.initials: S
authors.lastname: Mehra
authors.affiliation: Wadhwani Research Center for Biosciences and Bioengineering, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. Electronic address: sanjeeva@iitb.ac.in.
authors.forename: Sanjeeva
authors.initials: S
authors.lastname: Srivastava
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002939:Ciprofloxacin / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D048372:Streptomyces coelicolor / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002939:Ciprofloxacin
keywords: 2-DE; Mass spectrometry; Streptomyces coelicolor