Physical map of the linear chromosome of the bacterium Borrelia burgdorferi 212, a causative agent of Lyme disease, and localization of rRNA genes

Abstract

The spirochete Borrelia burgdorferi, which causes Lyme disease, and other members of the Borrelia genus are unique among characterized bacteria in having a linear chromosome. A restriction map of the chromosome of B. burgdorferi 212 was constructed by making extensive use of digestions in agarose blocks of restriction endonuclease fragments or chromosomal DNA that had been purified by pulsed-field gel electrophoresis. A total of 47 digestion sites for the enzymes SgrAI, SacII, MluI, BssHII, EagI, SmaI, NaeI, and ApaI were located. In most regions of the map, the gap between sites is 50 kbp or less, and 122 kbp is the largest distance between adjacent sites. The mapping data were consistent with previous conclusions that the B. burgdorferi chromosome is linear. The total size of the B. burgdorferi 212 chromosome was determined to be 946 kbp from the sums of the sizes of SacII, MluI, BssHII, and SmaI fragments, making it one of the smallest known bacterial chromosomes. The rRNA genes were found to be located near the center of the chromosome. One copy of the 16S rRNA gene (rrs) and two copies of the 23S rRNA gene (designated rrlA and rrlB), the latter pair in a tandem repeat, were detected. This particular complement of these two genes has not been reported for another bacterium.

Physical map of the genome of Oenococcus oeni PSU-1 and localization of genetic markers

“…Analysis of partial digestion products led to the complete AscI physical map, whereas the majority of NotI and S f l fragments have been assigned to the overlapping AscI fragments by twodimensional PFGE. To improve the visualization and assignment of fragments resulting from the secondary cleavage, which are sometimes hindered by the punctiform appearance of these fragments with the 2D techniques commonly used (Bautsch, 1988 ;Davidson et al, 1992;Tulloch et al, 1991), bands from the first dimension were individually excised and digested, rather than being collectively processed in a single agarose slice (see Methods). Mapping of NotI, Sfl and FseI sites was Physical map of Oenococcus oeni achieved mostly by hybridization, by using either linking clones or fragments generated by a different enzyme.…”

A Genomic Island of the Pathogen Leptospira interrogans Serovar Lai Can Excise from Its Chromosome

“…Genomic DNA of Leptospira was isolated using the phenol-chloroform method as previously described (17). For pulsed-field gel electrophoresis (PFGE), cells were embedded in agarose plugs as previously described (5). For digestion, DNA plugs were washed in Tris-EDTA buffer, followed by equilibration in 1ϫ restriction enzyme buffer, and then incubated overnight at 37°C in fresh 1ϫ restriction enzyme buffer containing 30 U NotI restriction enzyme.…”

Biological Aspects of Lyme Disease Spirochetes: Unique Bacteria of the Borrelia Burgdorferi Species Group

“…One characteristic feature of this microorganism is its unusual genome which consists of one linear chromosome with an approximate size of one mega base and several circular and linear plasmids 39,[56][57][58][59][60][61][62][63] . The Borrelia chromosome is relatively small compared to other bacterial chromosomes whose size varies from 580 to 9 300 kbp 64 .…”