The 44-kb linear plasmid molecule in the relapsing fever agent Borrelia duttonii strain Ly serve as a preservation of vmp genes.
Borrelia duttonii strain Ly, a causative agent of relapsing fever, contains a linear one megabase chromosome and 12 linear plasmid molecules. Here we report that the sequence of the 44-kb linear plasmid of strain Ly is found to contain variable major protein (vmp) genes for antigenic variation of relapsing fever borreliae. The determined sequence is of 44,010 bp except for both ends of the molecule. Of 39 open reading frames (ORFs) found in the sequence, 21 ORFs (named vmpA to U) showed moderate similarities with vmp genes for Borrelia hermsii. However, most of the vmp homologues are apparently nonfunctional because of their frameshifts within the sequence and/or absence of promoter and ribosome-binding signals upstream of their genes. RT-PCR experiments using the specific primer for each vmp gene revealed that vmpE, one of the vmp genes, was expressed at the location of the 44-kb plasmid molecule. The result suggests that the plasmid molecule may play a role in the preservation of the serotype switching of vmp genes in a mammalian host.
Tabuchi
Norihiko
N
Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan.
Mitani
Harumi
H
Seino
Satoshi
S
Fukunaga
Masahito
M
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001482:Base Composition; D001483:Base Sequence; D001898:Borrelia / Q000235:genetics*; D004269:DNA, Bacterial; D005798:Genes, Bacterial; D008074:Lipoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids; D012061:Relapsing Fever / Q000382:microbiology*; D017422:Sequence Analysis, DNA
D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D008074:Lipoproteins; C120881:vmp protein, Borrelia