AUTHOR=Liu Lu , Ye Meiping , Li Xiaobin , Li Jun , Deng Zixin , Yao Yu-Feng , Ou Hong-Yu 

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

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00442

DOI=10.3389/fcimb.2017.00442

ISSN=2235-2988

ABSTRACT=<p>The type VI secretion system (T6SS) is a class of sophisticated cell contact-dependent apparatus with anti-eukaryotic or anti-bacterial function. <italic>Klebsiella pneumoniae</italic> is one of the most common bacterial pathogens with resistance to the carbapenem antibiotics. However, little is known about the antibacterial T6SS in <italic>K. pneumoniae</italic>. Using core-component protein searches, we identified a putative T6SS gene cluster on the chromosome of the carbapenemase-producing <italic>K. pneumoniae</italic> (CRKP) strain HS11286. Intraspecies and interspecies competition assays revealed an antibacterial function of the HS11286 T6SS. The phospholipase Tle1<sup>KP</sup> 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 <italic>Escherichia coli</italic>. 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.</p>