J Med Microbiol 55 (2006), 931-942; DOI: 10.1099/jmm.0.46470-0
© 2006 Society for General Microbiology
ISSN 1473-5644
Immunoproteomics of Actinobacillus actinomycetemcomitans outer-membrane proteins reveal a highly immunoreactive peptidoglycan-associated lipoprotein
Maneesh Paul-Satyaseela1,
,
,
Maribasappa Karched1,
,
Zhao Bian2,
Riikka Ihalin1,
Thomas Borén1,
,
Anna Arnqvist1,
,
Casey Chen3 and
Sirkka Asikainen1
1 Oral Microbiology, Institute of Dentistry, Umeå University, SE-90187 Umeå, Sweden
2 Microbiology and Tumor Biology Center, Karolinska Hospital, Stockholm, Sweden
3 University of Southern California School of Dentistry, Los Angeles, CA 90089, USA
Correspondence
Sirkka Asikainen
Sirkka.Asikainen{at}odont.umu.se
Received 13 December 2005
Accepted 6 March 2006
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.
Abbreviations: 1D, one-dimensional; 2D, two-dimensional; MALDI-TOF MS, matrix-assisted laser desorption time-of-flight mass spectrometry; OMP, outer-membrane protein; PAL, peptidoglycan-associated lipoprotein; Q-TOF MS, quadrupole time-of-flight mass spectrometry; RT, room temperature.
These authors contributed equally to this work.
Present address: Center for Biological Evaluation and Research, US FDA, Bethesda, MD, USA.
Present address: Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
Copyright © 2006 Society for General Microbiology.