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The heat-modifiable outer membrane protein of Actinobacillus actinomycetemcomitans: relationship to OmpA proteins
1Department of Oral Biology, State University of New York, Buffalo 14214.
Abstract:
The outer membrane of Actinobacillus actinomycetemcomitans contains a 29-kDa protein which exhibits heat modifiability on sodium dodecyl sulfate-polyacrylamide gels and represents a major target for immunoglobulin G antibody in sera of periodontitis patients colonized by this organism. In the present study, the N-terminal amino acid sequence of the 29-kDa outer membrane protein was determined and compared with reported sequences for other known proteins. The heat-modifiable outer membrane protein of A. actinomycetemcomitans was found to exhibit significant N-terminal homology with the OmpA proteins of other gram-negative bacteria. Moreover, this protein reacted with antiserum raised against the purified OmpA protein of Escherichia coli K-12. Whether the heat-modifiable OMP of A. actinomycetemcomitans also shares functional properties of OmpA proteins, particularly with respect to bacteriophage receptor activity, is presently under investigation.
Insights
A key 29-kDa outer membrane protein from Actinobacillus actinomycetemcomitans shows N-terminal similarity to OmpA proteins in other bacteria. This finding suggests a potential role for this protein in periodontitis pathogenesis.
Area of Science:
- Microbiology
- Immunology
- Protein Chemistry
Background:
- Actinobacillus actinomycetemcomitans is implicated in periodontitis.
- Its outer membrane contains a 29-kDa heat-modifiable protein targeted by patient antibodies.
Purpose of the Study:
- To determine the N-terminal amino acid sequence of the 29-kDa outer membrane protein.
- To compare this sequence with known proteins and assess its relationship to OmpA proteins.
Main Methods:
- N-terminal amino acid sequencing of the 29-kDa protein.
- Comparison of the obtained sequence with databases of known protein sequences.
- Immunological cross-reactivity testing using antiserum against Escherichia coli OmpA.
Main Results:
- The N-terminal sequence of the 29-kDa protein showed significant homology to OmpA proteins of other Gram-negative bacteria.
- The protein reacted with antiserum raised against purified OmpA from Escherichia coli K-12.
Conclusions:
- The 29-kDa heat-modifiable outer membrane protein of Actinobacillus actinomycetemcomitans is likely an OmpA homolog.
- Further investigation is needed to confirm if it shares functional properties, such as bacteriophage receptor activity, with other OmpA proteins.