The Mycoplasma hominis vaa gene displays a mosaic gene structure |
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| Authors: | Thomas Boesen,Jeppe Emmersen,Lise T. Jensen,Sø ren A. Ladefoged,Poul Thorsen,Svend Birkelund,& Gunna Christiansen |
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| Affiliation: | Department of Medical Microbiology and Immunology, The Bartholin Building, University of Aarhus, DK-8000 Aarhus C, Denmark.,;Department of Molecular and Structural Biology, University of Aarhus, DK-800 Aarhus C, Denmark., Departments of,;Clinical Immunology,;Clinical Biochemistry, Aarhus University Hospital, Denmark.,;Department of Gynaecology and Obstetrics, Odense University Hospital, Denmark. |
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| Abstract: | Mycoplasma hominis contains a variable adherence-associated ( vaa ) gene. To classify variants of the vaa genes, we examined 42 M. hominis isolates by PCR, DNA sequencing and immunoblotting. This uncovered the existence of five gene categories. Comparison of the gene types revealed a modular composition of the Vaa proteins. The proteins constituted a conserved N-terminal part followed by a varying number of interchangeable cassettes encoding approximately 110 amino acids with conserved sequence boxes flanking the cassettes. The interchangeable cassettes showed a high mutual homology and a conserved leucine zipper motif. The smallest product contained only one cassette and the largest five. Additionally, two types of stop mutations caused by substitutions resulting in the expression of truncated Vaa proteins were observed. Our results expand the known potential of the Vaa system in generating antigen variation. |
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