Non-structural flagella genes affecting both polar and lateral flagella-mediated motility in Aeromonas hydrophila

Abstract

An Aeromonas hydrophila AH-3 miniTn5 mutant unable to produce polar and lateral flagella was isolated, in which the transposon was inserted into a gene whose encoded protein was an orthologue of the Campylobacter jejuni motility accessory factor (Maf) protein. In addition to this gene, several other related genes were found in this cluster that was adjacent to the region 2 genes of the polar flagellum. Mutation of the A. hydrophila AH-3 maf-2, neuB-like, flmD or neuA-like genes resulted in non-motile cells that were unable to swim or swarm due to the absence of both polar and lateral flagella. However, both polar and lateral flagellins were present but were unglycosylated. Although the A. hydrophila AH-3 or Aeromonas caviae Sch3N genes did not hybridize with each other at the nucleotide level, the gene products were able to fully complement the mutations in either bacterium. Furthermore, well-characterized C. jejuni genes involved in flagella glycosylation (Cj1293, -1294 and -1317) were fully able to complement A. hydrophila mutants in the corresponding genes (flmA, flmB and neuB-like). It was concluded that the maf-2, neuB-like, flmD and neuA-like genes are involved in the glycosylation of both the polar and the lateral flagella in Aeromonas strains.