Аннотация:In this report we describe two distinct approaches to develop new antibiotic resistance cassettes that allow for efficient selection of <i>Borrelia burgdorferi</i> transformants. The first approach utilizes fusions of borrelial flagellar promoters to antibiotic resistance markers from other bacteria. The <i>aacC1</i> gene, which encodes a gentamicin acetyltransferase, conferred a high level of gentamicin resistance in <i>B. burgdorferi</i> when expressed from these promoters. No cross-resistance occurred between this cassette and the kanamycin resistance cassette, which was previously developed in an analogous fashion. A second and different approach was taken to develop an efficient selectable marker that confers resistance to the antibiotic coumermycin A1. A synthetic gene was designed from the <i>gyrB301</i> allele of the coumermycin-resistant <i>B. burgdorferi</i> strain B31-NGR by altering the coding sequence at the wobble position. The resulting gene, <i>gyrB<sub>syn</sub></i>, encodes a protein identical to the product of <i>gyrB301</i>, but the genes share only 66% nucleotide identity. The nucleotide sequence of <i>gyrB<sub>syn</sub></i>is sufficiently divergent from the endogenous <i>B. burgdorferi</i><i>gyrB</i> gene to prevent recombination between them. The cassettes described in this paper improve our repertoire of genetic tools in <i>B. burgdorferi</i>. These studies also provide insight into parameters governing recombination and gene expression in <i>B. burgdorferi</i>.
