Home List of Titles Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop
Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/227461
- Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop
- Easton, Donna M.; Smith, Adam; Gomez Gallego, Sara; Foxwell, A. Ruth; Cripps, Allan W.; Kyd, Jennelle M.
- 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.
- Publication type
- Journal article
- Journal of Bacteriology, Vol. 187, no. 18 (Sep 2005), pp. 6528-6535
- Publication year
- FOR Code(s)
- 06 Biological Sciences; 07 Agricultural and Veterinary Sciences; 11 Medical and Health Sciences
- Amino acid sequence; Antigenicity; Bacteria; Bacterial DNA; DNA sequence; Escherichia coli; Flow cytometry; Genomic DNA; Gram-negative bacteria; Klebsiella pneumoniae; M35 protein; Moraxella catarrhalis; Negibacteria; Nucleotide sequence; Outer membrane proteins; Polyacrylamide gel electrophoresis; Polymerase chain reaction; Porins; Protein analysis; Protein expression; Protein folding; Recombinant protein; Western blotting
- American Society for Microbiology
- Publisher URL
- Copyright © 2005, American Society for Microbiology.
- Peer reviewed