The Yersinia enterocolitica Ysa type III secretion system is expressed during infections both in vitro and in vivo
Article first published online: 24 OCT 2013
© 2013 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Volume 2, Issue 6, pages 962–975, December 2013
How to Cite
MicrobiologyOpen 2013; 2(6): 962–975
- Issue published online: 6 DEC 2013
- Article first published online: 24 OCT 2013
- Manuscript Revised: 12 SEP 2013
- Manuscript Accepted: 12 SEP 2013
- Manuscript Received: 16 JUL 2013
- National Institutes of Health. Grant Numbers: R21 AI156042, T32 AI60555
- Sandia National Laboratories' LDRD. Grant Numbers: 165767, 171001
- In vivo expression;
- Y. enterocolitica ;
Yersinia enterocolitica biovar 1B maintains two type III secretion systems (T3SS) that are involved in pathogenesis, the plasmid encoded Ysc T3SS and the chromosomally encoded Ysa T3SS. In vitro, the Ysa T3SS has been shown to be expressed only at 26°C in a high-nutrient medium containing an exceptionally high concentration of salt – an artificial condition that provides no clear insight on the nature of signal that Y. enterocolitica responds to in a host. However, previous research has indicated that the Ysa system plays a role in the colonization of gastrointestinal tissues of mice. In this study, a series of Ysa promoter fusions to green fluorescent protein gene (gfp) were created to analyze the expression of this T3SS during infection. Using reporter strains, infections were carried out in vitro using HeLa cells and in vivo using the mouse model of yersiniosis. Expression of green fluorescent protein (GFP) was measured from the promoters of yspP (encoding a secreted effector protein) and orf6 (encoding a structural component of the T3SS apparatus) in vitro and in vivo. During the infection of HeLa cells GFP intensity was measured by fluorescence microscopy, while during murine infections GFP expression in tissues was measured by flow cytometry. These approaches, combined with quantification of yspP mRNA transcripts by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), demonstrate that the Ysa system is expressed in vitro in a contact-dependent manner, and is expressed in vivo during infection of mice.