title: The Borrelia burgdorferi flaB promoter has an extended -10 element and includes a T-rich -35/-10 spacer sequence that is essential for optimal activity.
abstract: In this study, we investigated the functional elements of the flaB promoter of Borrelia burgdorferi. Promoter function was examined in a high-passage variant of strain JD1 using a set of 5' deletions and mutations within the flaB promoter. Expression from the modified flaB promoters was assayed using the gene for green fluorescent protein (gfp) as a reporter. Although the -35 element of the promoter stimulated promoter activity, its disruption did not negate expression. Sequences upstream of the -35 had no effect on expression. The -35/-10 spacer region composed of a T-rich sequence was critical for optimal promoter function. Surprisingly, a cytosine at the -13 site was found to be more favorable for transcription compared with a guanosine at the same site. Based on these results and other characteristics, we propose that the B. burgdorferi flaB promoter is an example of an extended -10 promoter. Further, the T-rich spacer is a key element of the flaB promoter that contributes to the abundance of the flagellar core protein in Borrelia species.
authors.affiliation: Tulane National Primate Research Center, Division of Bacteriology and Parasitology, Tulane University Health Sciences Center, Covington, LA 70433, USA.
authors.forename: Aarti
authors.initials: A
authors.lastname: Gautam
authors.forename: Marianne
authors.initials: M
authors.lastname: Hathaway
authors.forename: Ramesh
authors.initials: R
authors.lastname: Ramamoorthy
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D025065:Borrelia burgdorferi / Q000235:genetics*; D005408:Flagellin / Q000235:genetics*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D005408:Flagellin; C416532:flaB flagellin; D049452:Green Fluorescent Proteins