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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Microbiol. | doi: 10.3389/fmicb.2019.01707

Amino Acid Substitutions and Differential Gene Expression of Outer Membrane Proteins in Adherent-Invasive Escherichia coli

  • 1Laboratory of Molecular Microbiology, Biology Department, University of Girona, Spain
  • 2Service of Microbiology, Marqués de Valdecilla University Hospital, Spain
  • 3Biochemistry and Molecular Biology unit, Biology Department, University of Girona, Spain
  • 4Microbiology Unit, Hospital Universitario Reina Sofía, Spain
  • 5Department of Microbiology, Universidad de Córdoba, Spain

Variations in the sequence and/or the expression of outer membrane proteins (OMPs) may modulate bacterial virulence. OmpA and OmpC have been involved in the interaction of adherent-invasive Escherichia coli (AIEC) strain LF82 with intestinal epithelial cells. Scarce data exist about OMPs sequence variants in a collection of AIEC strains, and no study of OMPs expression during infection exists. We aimed to determine whether particular mutations or differential expression of OMPs are associated with AIEC virulence.
The ompA, ompC and ompF genes in 14 AIEC and 30 non-AIEC strains were sequenced by Sanger method, and the protein expression profile was analyzed by urea-SDS-PAGE. Gene expression was determined during in vitro bacterial infection of intestine-407 cells by RT-qPCR.
The distribution of amino acid substitutions in OmpA-A200V, OmpC-S89N, V220I and W231D associated with pathotype and specific changes (OmpA-A200V, OmpC-V220I and D232A, OmpF-E51V and M60K) correlated with adhesion and/or invasion indices. OMPs protein levels did not differ according to pathotype. Higher ompA and ompF expression levels were reported in AIEC growing in the supernatants of infected cultures compared with those in non-AIEC strains (p<0.030). Interestingly, AIEC decreased OMPs expression when growing in association with cells (p<0.032), whereas non-AIEC strains did not significantly alter OMPs expression under this condition (p>0.577).
In conclusion, the AIEC-associated OMPs amino acid substitutions identified herein could facilitate a better interaction with the host, and OMPs gene expression changes at different stages of AIEC infection suggest that these proteins may play a distinct role in adhesion and/or in intracellular survival.

Keywords: Adherent-invasive E. coli (AIEC), virulence genes, amino acid substitutions, Gene Expression, outer membrane protein, Infection

Received: 25 Mar 2019; Accepted: 10 Jul 2019.

Edited by:

Lisa Sedger, University of Technology Sydney, Australia

Reviewed by:

Cecilia Ambrosi, Sapienza University of Rome, Italy
Julien Delmas, Université Clermont Auvergne, France  

Copyright: © 2019 Camprubí-Font, Ruiz del Castillo, Barrabés Vera, Martinez Martinez and Martinez-Medina. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Margarita Martinez-Medina, University of Girona, Laboratory of Molecular Microbiology, Biology Department, Girona, 17071, Catalonia, Spain, marga.martinez@udg.edu