Dataset Information

An unexpected flaA homolog is present and expressed in Borrelia burgdorferi.

ABSTRACT: Most investigators have assumed that the periplasmic flagella (PFs) of Borrelia burgdorferi are composed of only one flagellin protein. The PFs of most other spirochete species are complex: these PFs contain an outer sheath of FlaA proteins and a core filament of FlaB proteins. During an analysis of a chemotaxis gene cluster of B. burgdorferi 212, we were surprised to find a flaA gene homolog with a deduced polypeptide having 54 to 58% similarity to FlaA from other spirochetes. Like other FlaA proteins, B. burgdorferi FlaA has a conserved signal sequence at its N terminus. Based on reverse transcription-PCR and primer extension analysis, this flaA homolog and five chemotaxis genes constitute a motility-chemotaxis operon. Immunoblots using anti-FlaA serum from Treponema pallidum and a lysate of B. burgdorferi showed strong reactivity to a protein of 38.0 kDa, which is consistent with the expression of flaA in growing cells.

SUBMITTER: Ge Y

PROVIDER: S-EPMC178730 | biostudies-other | 1997 Jan

REPOSITORIES: biostudies-other

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An unexpected flaA homolog is present and expressed in Borrelia burgdorferi.

Ge Y Y Charon N W NW

Journal of bacteriology 19970101 2

Most investigators have assumed that the periplasmic flagella (PFs) of Borrelia burgdorferi are composed of only one flagellin protein. The PFs of most other spirochete species are complex: these PFs contain an outer sheath of FlaA proteins and a core filament of FlaB proteins. During an analysis of a chemotaxis gene cluster of B. burgdorferi 212, we were surprised to find a flaA gene homolog with a deduced polypeptide having 54 to 58% similarity to FlaA from other spirochetes. Like other FlaA p ...[more]

PMID: 8990312

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Project description:The spirochete which causes Lyme disease, Borrelia burgdorferi, has many features common to other spirochete species. Outermost is a membrane sheath, and within this sheath are the cell cylinder and periplasmic flagella (PFs). The PFs are subterminally attached to the cell cylinder and overlap in the center of the cell. Most descriptions of the B. burgdorferi flagellar filaments indicate that these organelles consist of only one flagellin protein (FlaB). In contrast, the PFs from other spirochete species are comprised of an outer layer of FlaA and a core of FlaB. We recently found that a flaA homolog was expressed in B. burgdorferi and that it mapped in a fla/che operon. These results led us to analyze the PFs and FlaA of B. burgdorferi in detail. Using Triton X-100 to remove the outer membrane and isolate the PFs, we found that the 38.0-kDa FlaA protein purified with the PFs in association with the 41.0-kDa FlaB protein. On the other hand, purifying the PFs by using Sarkosyl resulted in no FlaA in the isolated PFs. Sarkosyl has been used by others to purify B. burgdorferi PFs, and our results explain in part their failure to find FlaA. Unlike other spirochetes, B. burgdorferi FlaA was expressed at a lower level than FlaB. In characterizing FlaA, we found that it was posttranslationally modified by glycosylation, and thus it resembles its counterpart from Serpulina hyodysenteriae. We also tested if FlaA was synthesized in a spontaneously occurring PF mutant of B. burgdorferi (HB19Fla-). Although this mutant still synthesized flaA message in amounts similar to the wild-type amounts, it failed to synthesize FlaA protein. These results suggest that, in agreement with data found for FlaB and other spirochete flagellar proteins, FlaA is likely to be regulated on the translational level. Western blot analysis using Treponema pallidum anti-FlaA serum indicated that FlaA was antigenically well conserved in several spirochete species. Taken together, the results indicate that both FlaA and FlaB comprise the PFs of B. burgdorferi and that they are regulated differently from flagellin proteins of other bacteria.

Dataset Information

An unexpected flaA homolog is present and expressed in Borrelia burgdorferi.

Publications

An unexpected flaA homolog is present and expressed in Borrelia burgdorferi.

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