Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins

OBJECTIVES: The outer membrane protein M35 of Moraxella catarrhalis is an antigenically conserved porin. Knocking out M35 significantly increases the MICs of aminopenicillins. The aim of this study was to determine the biological mechanism of this potentially new antimicrobial resistance mechanism o...

Descripción completa

Detalles Bibliográficos
Autores principales: Jetter, Marion, Spaniol, Violeta, Troller, Rolf, Aebi, Christoph
Formato: Texto
Lenguaje:English
Publicado: Oxford University Press 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941675/
https://www.ncbi.nlm.nih.gov/pubmed/20801781
http://dx.doi.org/10.1093/jac/dkq312
_version_ 1782186923493687296
author Jetter, Marion
Spaniol, Violeta
Troller, Rolf
Aebi, Christoph
author_facet Jetter, Marion
Spaniol, Violeta
Troller, Rolf
Aebi, Christoph
author_sort Jetter, Marion
collection PubMed
description OBJECTIVES: The outer membrane protein M35 of Moraxella catarrhalis is an antigenically conserved porin. Knocking out M35 significantly increases the MICs of aminopenicillins. The aim of this study was to determine the biological mechanism of this potentially new antimicrobial resistance mechanism of M. catarrhalis and the behaviour of M35 in general stress situations. METHODS: PCR using m35-specific primers was used to detect the m35 gene in clinical isolates. The m35 mRNA expression of strains 300, O35E and 415 after exposure to amoxicillin and different stress conditions was measured by real-time PCR and normalized in relation to their 16S rRNA expression. The expression of M35 protein was analysed by SDS-PAGE and western blotting. RESULTS: Screening of 52 middle ear isolates resulted in positive PCR products for all tested strains. The analysis of m35 mRNA expression after amoxicillin treatment showed 24%–85% down-regulation compared with the respective amoxicillin-free controls in all three strains tested. Also, analysis of protein concentrations revealed lower M35 expression after growth with amoxicillin. Investigation of M35 during general stress responses showed down-regulation of the porin with growth at 26°C and 42°C, under hyperosmolar stress and under iron restriction. CONCLUSIONS: The reduced expression of M35 after aminopenicillin exposure indicates a novel resistance mechanism against aminopenicillins in M. catarrhalis, which may be relevant in vivo. The differences in expression after different stress treatments demonstrate that M35 is involved in general stress responses.
format Text
id pubmed-2941675
institution National Center for Biotechnology Information
language English
publishDate 2010
publisher Oxford University Press
record_format MEDLINE/PubMed
spelling pubmed-29416752010-09-20 Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins Jetter, Marion Spaniol, Violeta Troller, Rolf Aebi, Christoph J Antimicrob Chemother Original Research OBJECTIVES: The outer membrane protein M35 of Moraxella catarrhalis is an antigenically conserved porin. Knocking out M35 significantly increases the MICs of aminopenicillins. The aim of this study was to determine the biological mechanism of this potentially new antimicrobial resistance mechanism of M. catarrhalis and the behaviour of M35 in general stress situations. METHODS: PCR using m35-specific primers was used to detect the m35 gene in clinical isolates. The m35 mRNA expression of strains 300, O35E and 415 after exposure to amoxicillin and different stress conditions was measured by real-time PCR and normalized in relation to their 16S rRNA expression. The expression of M35 protein was analysed by SDS-PAGE and western blotting. RESULTS: Screening of 52 middle ear isolates resulted in positive PCR products for all tested strains. The analysis of m35 mRNA expression after amoxicillin treatment showed 24%–85% down-regulation compared with the respective amoxicillin-free controls in all three strains tested. Also, analysis of protein concentrations revealed lower M35 expression after growth with amoxicillin. Investigation of M35 during general stress responses showed down-regulation of the porin with growth at 26°C and 42°C, under hyperosmolar stress and under iron restriction. CONCLUSIONS: The reduced expression of M35 after aminopenicillin exposure indicates a novel resistance mechanism against aminopenicillins in M. catarrhalis, which may be relevant in vivo. The differences in expression after different stress treatments demonstrate that M35 is involved in general stress responses. Oxford University Press 2010-10 2010-08-27 /pmc/articles/PMC2941675/ /pubmed/20801781 http://dx.doi.org/10.1093/jac/dkq312 Text en © The Author 2010. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. http://creativecommons.org/licenses/by-nc/2.5/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Jetter, Marion
Spaniol, Violeta
Troller, Rolf
Aebi, Christoph
Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title_full Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title_fullStr Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title_full_unstemmed Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title_short Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
title_sort down-regulation of porin m35 in moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941675/
https://www.ncbi.nlm.nih.gov/pubmed/20801781
http://dx.doi.org/10.1093/jac/dkq312
work_keys_str_mv AT jettermarion downregulationofporinm35inmoraxellacatarrhalisbyaminopenicillinsandenvironmentalfactorsanditspotentialcontributiontothemechanismofresistancetoaminopenicillins
AT spaniolvioleta downregulationofporinm35inmoraxellacatarrhalisbyaminopenicillinsandenvironmentalfactorsanditspotentialcontributiontothemechanismofresistancetoaminopenicillins
AT trollerrolf downregulationofporinm35inmoraxellacatarrhalisbyaminopenicillinsandenvironmentalfactorsanditspotentialcontributiontothemechanismofresistancetoaminopenicillins
AT aebichristoph downregulationofporinm35inmoraxellacatarrhalisbyaminopenicillinsandenvironmentalfactorsanditspotentialcontributiontothemechanismofresistancetoaminopenicillins