Identification and Characterization of an Antibacterial Type VI Secretion System in the Carbapenem-Resistant Strain Klebsiella pneumoniae HS11286

Front Cell Infect Microbiol. 2017 Oct 12;7:442. doi: 10.3389/fcimb.2017.00442. eCollection 2017.

Abstract

The type VI secretion system (T6SS) is a class of sophisticated cell contact-dependent apparatus with anti-eukaryotic or anti-bacterial function. Klebsiella pneumoniae is one of the most common bacterial pathogens with resistance to the carbapenem antibiotics. However, little is known about the antibacterial T6SS in K. pneumoniae. Using core-component protein searches, we identified a putative T6SS gene cluster on the chromosome of the carbapenemase-producing K. pneumoniae (CRKP) strain HS11286. Intraspecies and interspecies competition assays revealed an antibacterial function of the HS11286 T6SS. The phospholipase Tle1KP was found to be an effector protein that is transferred by T6SS. The overexpression of this effector gene in the periplasm caused severe growth inhibition of Escherichia coli. A sub-inhibitory concentration of β-lactam antibiotics stimulated the expression and secretion of the HS11286 T6SS and enhanced T6SS-dependent killing. It suggested that the antibiotics might be an impact factor for the T6SS secretion and antibacterial activity.

Keywords: Klebsiella pneumoniae; antibacterial; antibiotic stress; phospholipase; type VI secretion system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / metabolism
  • Carbapenems / pharmacology*
  • Coculture Techniques
  • Escherichia coli / genetics
  • Genetic Vectors / genetics
  • Humans
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / genetics*
  • Klebsiella pneumoniae / metabolism
  • Multigene Family
  • Mutation / genetics
  • Phospholipases / metabolism
  • Protein Transport
  • Sputum / microbiology
  • Type VI Secretion Systems / genetics*
  • beta-Lactam Resistance*
  • beta-Lactamases / metabolism

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Carbapenems
  • Type VI Secretion Systems
  • Phospholipases
  • beta-Lactamases
  • carbapenemase