RNase E regulates the Yersinia type 3 secretion system

Department of Microbiology and Immunology, Department of Biochemistry and Molecular Biology, University of Miami, Miller School of Medicine, Miami, Florida

^* To whom correspondence should be addressed. Email: kschesser{at}med.miami.edu.

	Abstract

Yersinia spp. uses a type 3 secretion system (T3SS) to directly inject 6 proteins into macrophages and any impairment of this process results in a profound reduction in virulence. We previously showed that the exoribonuclease polynucleotide phosphorylase (PNPase) was required for optimal T3SS functioning in Y. pseudotuberculosis and Y. pestis. Here we report that Y. pseudotuberculosis cells with reduced ribonuclease (RNase) E activity are likewise impaired in T3SS functioning and that phenotypically they resemble pnp cells. RNase E does not affect expression levels of the T3SS substrates but instead, like PNPase, regulates a terminal event in the secretion pathway. This similarity, together with the fact that RNase E and PNPase can be readily co-purified from Y. pseudotuberculosis cell extracts, suggests that these two ribonucleases regulate T3SS activity through a common mechanism. This is the first report that RNase E activity impacts the T3SS as well as playing a more general role in infectivity.