Immunoproteomics of Actinobacillus actinomycetemcomitans outer-membrane proteins reveal a highly immunoreactive peptidoglycan-associated lipoprotein.
In a search for novel bioactive cell surface structures of periodontal pathogens, it was found that sera from two patients with Actinobacillus actinomycetemcomitans-associated infections reacted strongly at 17 kDa on immunoblots of A. actinomycetemcomitans outer-membrane protein (OMP) preparations. The 17 kDa antigen was also recognized by anti-CsgA (Escherichia coli curli major subunit) antibody. The 17 kDa A. actinomycetemcomitans protein was identified as peptidoglycan-associated lipoprotein (PAL; AaPAL) by two-dimensional immunoblotting and subsequent sequence analysis by mass spectrometry and bioinformatics tools. AaPAL was an OMP and a lipoprotein, and it had an OmpA-like domain. In a group of middle-aged subjects (n = 26), serum reactivity to AaPAL was associated with the presence of periodontitis but not with the oral detection of A. actinomycetemcomitans. Both human sera and rabbit antisera against three different types of antigens, the gel-purified AaPAL, A. actinomycetemcomitans whole-cell antigens, and CsgA, recognized putative PALs of oral haemophili in addition to AaPAL. The results demonstrated that the novel AaPAL is a conserved bacterial lipoprotein. It is expressed in vivo and is strongly immunoreactive. The antigenic cross-reactivity found between AaPAL and oral haemophili may enhance local and systemic immuno-inflammatory reactions in periodontitis.
Paul-Satyaseela
Maneesh
M
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
Karched
Maribasappa
M
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
Bian
Zhao
Z
Microbiology and Tumor Biology Center, Karolinska Hospital, Stockholm, Sweden.
Ihalin
Riikka
R
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
Borén
Thomas
T
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
Arnqvist
Anna
A
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
Chen
Casey
C
University of Southern California School of Dentistry, Los Angeles, CA 90089, USA.
Asikainen
Sirkka
S
Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden.
D000189:Actinobacillus Infections / Q000276:immunology* / Q000382:microbiology; D000328:Adult; D000368:Aged; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001483:Base Sequence; D005260:Female; D006801:Humans; D008074:Lipoproteins / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010457:Peptidoglycan / Q000276:immunology*; D010518:Periodontitis / Q000276:immunology / Q000382:microbiology*; D040901:Proteomics / Q000379:methods; D011817:Rabbits
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D008074:Lipoproteins; D010457:Peptidoglycan