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Journal of Bacteriology, July 2002, p. 3712-3722, Vol. 184, No. 13
0021-9193/02/$04.00+0 DOI: 10.1128/JB.184.13.3712-3722.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Department of Bacteriology, National Veterinary Institute, SE-751 89 Uppsala,1 Department of Microbiology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden,2 Laboratoire d'Etudes et de Recherches en Pathologie Bovine et Hygiène des Viandes, AFSSA-Site de Lyon, FR-69364, France3
Received 24 September 2001/ Accepted 10 April 2002
A variable surface protein, Vmm, of the bovine pathogen Mycoplasma mycoides subsp. mycoides small colony type (M. mycoides SC) has been identified and characterized. Vmm was specific for the SC biotype and was expressed by 68 of 69 analyzed M. mycoides SC strains. The protein was found to undergo reversible phase variation at a frequency of 9 x 10-4 to 5 x 10-5 per cell per generation. The vmm gene was present in all of the 69 tested M. mycoides SC strains and encodes a lipoprotein precursor of 59 amino acids (aa), where the mature protein was predicted to be 36 aa and was anchored to the membrane by only the lipid moiety, as no transmembrane region could be identified. DNA sequencing of the vmm gene region from ON and OFF clones showed that the expression of Vmm was regulated at the transcriptional level by dinucleotide insertions or deletions in a repetitive region of the promoter spacer. Vmm-like genes were also found in four closely related mycoplasmas, Mycoplasma capricolum subsp. capricolum, M. capricolum subsp . capripneumoniae, Mycoplasma sp. bovine serogroup 7, and Mycoplasma putrefaciens. However, Vmm could not be detected in whole-cell lysates of these species, suggesting that the proteins encoded by the vmm-like genes lack the binding epitope for the monoclonal antibody used in this study or, alternatively, that the Vmm-like proteins were not expressed.
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