Functional analysis of a large non-conserved region of FlgK (HAP1) from Rhodobacter sphaeroides |
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Authors: | David J. Castillo Teresa Ballado Laura Camarena Georges Dreyfus |
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Affiliation: | (1) Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apdo. Postal 70-243 Cd. Universitaria, 04510 Mexico, DF, Mexico;(2) Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510 Mexico, DF, Mexico |
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Abstract: | The single subpolar flagellum of Rhodobacter sphaeroides shows an enlarged hook-filament junction. One of the two proteins that compose this section of the filament is HAP1 Rs (FlgK Rs ) it contains a central non-conserved region of 860 amino acids that makes this protein about three times larger than its homologue in Salmonella enterica serovar Typhimurium. We investigated the role of this central portion of the unusually large HAP1 protein of R. sphaeroides by monitoring the effects of serial deletions in flgK Rs , the gene encoding HAP1 Rs , on swimming and swarming. Two deletion mutants did not assemble functional flagella, two were paralyzed and five exhibited reduced free-swimming speeds. Some mutants produced unusual swarming patterns on soft agar without or with Ficoll 400. A segment of approximately 200-aa of the central region of HAP1 Rs that aligns with the variable region of the flagellin sequence from other γ- and β-proteobacteria was also found. Therefore, it is possible that the origin of this large central domain of HAP1 Rs could be associated with an event of horizontal transfer and subsequent duplications and/or insertions. |
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Keywords: | Rhodobacter sphaeroides Bacterial flagellum Hook-filament junction HAP1 Rs Motility |
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