Gene rearrangements in the vsa locus of Mycoplasma pulmonis.
The vsa genes of Mycoplasma pulmonis encode the V-1 lipoproteins. Most V-1 proteins contain repetitive domains and are thought to be involved in mycoplasma-host cell interactions. Previously, we have reported the isolation and characterization of six vsa genes comprising a 10-kb region of the genome of M. pulmonis strain KD735-15. In the current study, vsa-specific probes were used to clone several fragments from a genomic library of KD735-15 DNA and assemble a single 20-kb contig containing 11 vsa genes. The middle region of the vsa locus contains a large open reading frame (ORF) that is not a vsa gene and has undergone an internal deletion in some strains. The ORF is predicted to encode a membrane protein that may have a role in disease pathogenesis. To examine vsa genes in a strain of M. pulmonis that is unrelated to KD735-15, strain CT was studied. Through Southern hybridization and genomic cloning analyses, CT was found to possess homologs of the KD735-15 vsaA, -C, -E, and -F genes and two unique genes (vsaG and vsaH) that were not found in KD735-15. High-frequency, site-specific DNA inversions serve to regulate the phase-variable production of individual V-1 proteins. As a result of the sequence analysis of vsa recombination products, a model in which DNA inversion arises from strand exchange involving at least six nucleotides of the vrs box is proposed.
Shen
X
X
Department of Comparative Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Gumulak
J
J
Yu
H
H
French
C T
CT
Zou
N
N
Dybvig
K
K
D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial; D015321:Gene Rearrangement; D005798:Genes, Bacterial; D008074:Lipoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009174:Mycoplasma / Q000235:genetics*; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008074:Lipoproteins