The antigenic domain of flagellin from S. paratyphi shares a structural fold with subtilisin

Genetic loci of major antigenic protein genes of Edwardsiella tarda

Seven antigenic proteins of Edwardsiella tarda were identified by using a rabbit polyclonal antiserum. Four of these proteins also reacted with a Japanese flounder antiserum. The amino acid sequences had identity to lipoproteins, periplasmic proteins, and exported and secreted proteins with roles in transport of metabolites across the cell membrane, stress response, and motility. These genes and their products are useful for developing DNA or recombinant subunit vaccines to control edwardsiellosis.

Spinning tails

The torque-generating, direction-reversing switch proteins of the bacterial flagellar rotary motor form a cytoplasmic extension of the bacterial flagellar basal body. 10 A maps, obtained by electron cryomicroscopy, of the bacterial filament reveal an unusual alpha domain which forms the protein-subunit export channel. The details of subunit export, assembly, and assembly-monitoring machinery are becoming clearer.

Recombinational basis of serovar diversity in Salmonella enterica

The fliC gene, which encodes phase 1 flagellin, was sequenced in strains of 15 Salmonella enterica serovars expressing flagellar antigenic factors of the g series. The occurrence of each of the flagellin serotypes g,m, m,t, and g,z51 in distantly related strains is the result of horizontal exchange of DNA, as indicated by identity or close similarity in nucleotide sequence of all or parts of the antigenic factor-determining central region of fliC. The flagellin genes of some serovars are complex mosaic structures composed of diverse segments derived through multiple recombination events. Thus, recombination of horizontally transferred segments (intragenic) or entire genes (assortative) within and among subspecies is identified as a major evolutionary mechanism generating both allelic variation at the fliC locus and serovar diversity in natural populations. Evidence that flagellar serological diversity is promoted by diversifying selection in adaptation to host immune defense system or flagellotropic phage is discussed.