HOMEPRODUCTSCOMPANYCONTACTFAQResearchDictionaryPharmaSign Up FREE or Login

Identification of SlpB, a Cytotoxic Protease from Serratia marcescens.

Abstract
The Gram-negative bacterium and opportunistic pathogen Serratia marcescens causes ocular infections in healthy individuals. Secreted protease activity was characterized from 44 ocular clinical isolates, and a higher frequency of protease-positive strains was observed among keratitis isolates than among conjunctivitis isolates. A positive correlation between protease activity and cytotoxicity to human corneal epithelial cells in vitro was determined. Deletion of prtS in clinical keratitis isolate K904 reduced, but did not eliminate, cytotoxicity and secreted protease production. This indicated that PrtS is necessary for full cytotoxicity to ocular cells and implied the existence of another secreted protease(s) and cytotoxic factors. Bioinformatic analysis of the S. marcescens Db11 genome revealed three additional open reading frames predicted to code for serralysin-like proteases noted here as slpB, slpC, and slpD. Induced expression of prtS and slpB, but not slpC and slpD, in strain PIC3611 rendered the strain cytotoxic to a lung carcinoma cell line; however, only prtS induction was sufficient for cytotoxicity to a corneal cell line. Strain K904 with deletion of both prtS and slpB genes was defective in secreted protease activity and cytotoxicity to human cell lines. PAGE analysis suggests that SlpB is produced at lower levels than PrtS. Purified SlpB demonstrated calcium-dependent and AprI-inhibited protease activity and cytotoxicity to airway and ocular cell lines in vitro. Lastly, genetic analysis indicated that the type I secretion system gene, lipD, is required for SlpB secretion. These genetic data introduce SlpB as a new cytotoxic protease from S. marcescens.
AuthorsRobert M Q Shanks, Nicholas A Stella, Kristin M Hunt, Kimberly M Brothers, Liang Zhang, Patrick H Thibodeau
JournalInfection and immunity (Infect Immun) Vol. 83 Issue 7 Pg. 2907-16 (Jul 2015) ISSN: 1098-5522 [Electronic] United States
PMID25939509 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2015, American Society for Microbiology. All Rights Reserved.
Chemical References
  • Bacterial Toxins
  • Virulence Factors
  • Peptide Hydrolases
Topics
  • Bacterial Toxins (genetics, metabolism)
  • Cell Line
  • Cell Survival (drug effects)
  • Epithelial Cells (drug effects)
  • Eye Infections, Bacterial (microbiology)
  • Humans
  • Peptide Hydrolases (genetics, metabolism)
  • Serratia Infections (microbiology)
  • Serratia marcescens (enzymology, genetics, isolation & purification)
  • Virulence Factors (genetics, metabolism)

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research graph!


Choose Username:
Email:
Password:
Verify Password:
Enter Code Shown: