Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop

Easton, D. M., Smith, A., Gallego, S. G., Foxwell, A. R., Cripps, A. W. and Kyd, J. M. (2005) Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop. Journal of Bacteriology, 187 18: 6528-6535. doi:10.1128/JB.187.18.6528-6535.2005

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Author Easton, D. M.
Smith, A.
Gallego, S. G.
Foxwell, A. R.
Cripps, A. W.
Kyd, J. M.
Title Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop
Formatted title
Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop
Journal name Journal of Bacteriology   Check publisher's open access policy
ISSN 0021-9193
1067-8832
1098-5530
Publication date 2005-09
Sub-type Article (original research)
DOI 10.1128/JB.187.18.6528-6535.2005
Open Access Status File (Publisher version)
Volume 187
Issue 18
Start page 6528
End page 6535
Total pages 8
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Language eng
Formatted abstract
Moraxella catarrhalis is a gram-negative bacterium that is mainly responsible for respiratory tract infections. In this study we report a novel outer membrane protein (OMP), designated M35, with a molecular mass of 36.1 kDa. This protein was structurally homologous to classic gram-negative porins, such as OMP C from Escherichia coli and OMP K36 from Klebsiella pneumoniae, with a predicted structure of 8 surface loops and 16 antiparallel β-sheets. The DNA sequences of the genes from IS diverse clinical isolates showed that the gene was highly conserved (99.6 to 100% of nucleotides), with only one isolate (ID78LN266) having base variations that resulted in amino acid substitutions. Electrophoresis and analysis of recognition of the protein using mouse anti-M35 sera showed that M35 was expressed on the bacterial surface and constitutively expressed across M. catarrhalis isolates, with only ID7SLN266 showing poor antibody recognition. Our results showed that the single amino acid mutation in loop 3 significantly affected antibody recognition, indicating that loop 3 appeared to contain an immunodominant B-cell epitope. The antibody specificity to loop 3 may be a potential mechanism for evasion of host immune responses targeted to M35, since loop 3 should theoretically orientate into the porin channel. Thus, M35 is a highly conserved, surface-expressed protein that is of significance for its potential functional role as an M. catarrhalis porin and is of interest as a vaccine candidate.
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Veterinary Science Publications
 
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Created: Wed, 08 Jun 2011, 17:33:03 EST by Dr Donna M Easton on behalf of School of Veterinary Science