Document Detail

Trimeric structure of major outer membrane proteins homologous to OmpA in Porphyromonas gingivalis.
MedLine Citation:
PMID:  15659668     Owner:  NLM     Status:  MEDLINE    
The major outer membrane proteins Pgm6 (41 kDa) and Pgm7 (40 kDa) of Porphyromonas gingivalis ATCC 33277 are encoded by open reading frames pg0695 and pg0694, respectively, which form a single operon. Pgm6 and Pgm7 (Pgm6/7) have a high degree of similarity to Escherichia coli OmpA in the C-terminal region and are predicted to form eight-stranded beta-barrels in the N-terminal region. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Pgm6/7 appear as bands with apparent molecular masses of 40 and 120 kDa, with and without a reducing agent, suggesting a monomer and trimer, respectively. To verify the predicted trimeric structure and function of Pgm6/7, we constructed three mutants with pg0695, pg0694, or both deleted. The double mutant produced no Pgm6/7. The single-deletion mutants appeared to contain less Pgm7 and Pgm6 and to form homotrimers that migrated slightly faster (115 kDa) and slower (130 kDa), respectively, than wild-type Pgm6/7 under nonreducing conditions. N-terminal amino acid sequencing and mass spectrometry analysis of partially digested Pgm6/7 detected only fragments from Pgm6 and Pgm7. Two-dimensional, diagonal electrophoresis and chemical cross-linking experiments with or without a reducing agent clearly showed that Pgm6/7 mainly form stable heterotrimers via intermolecular disulfide bonds. Furthermore, growth retardation and arrest of the three mutants and increased permeability of their outer membranes indicated that Pgm6/7 play an important role in outer membrane integrity. Based on results of liposome swelling experiments, these proteins are likely to function as a stabilizer of the cell wall rather than as a major porin in this organism.
Keiji Nagano; Erik K Read; Yukitaka Murakami; Takashi Masuda; Toshihide Noguchi; Fuminobu Yoshimura
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of bacteriology     Volume:  187     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2005 Feb 
Date Detail:
Created Date:  2005-01-20     Completed Date:  2005-03-01     Revised Date:  2013-04-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  902-11     Citation Subset:  IM    
Department of Microbiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Aichi 464-8650, Japan.
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MeSH Terms
Bacterial Outer Membrane Proteins / chemistry,  genetics*
Base Sequence
DNA Primers
Molecular Sequence Data
Multiprotein Complexes
Mutagenesis, Insertional
Periodontitis / microbiology
Porphyromonas gingivalis / genetics*,  growth & development,  isolation & purification
Sequence Deletion
Reg. No./Substance:
0/Bacterial Outer Membrane Proteins; 0/DNA Primers; 0/Multiprotein Complexes; 0/Pgm6 protein, Porphyromonas gingivalis; 0/Pgm7 protein, Porphyromonas gingivalis; 149024-69-1/OMPA outer membrane proteins

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