Physical characterization of Caulobacter crescentus flagella.

Preparations of intact flagella isolated from Caulobacter crescentus CB13B1a were found to contain two protein species of apparent molecular weights 28,000 and 25,000. Both proteins cross-reacted completely with each other and with purified flagella in Ouchterlony double-immunodiffusion assays. The amino acid compositions of the isolated proteins were similar to one another but precluded any precursor-product relationship. Absence of both the 25,000- and 28,000-molecular-weight proteins from a number of nonmotile mutants and the simultaneous reappearance of these proteins in a motile revertant provide further evidence of the relationship of these two proteins to flagellar structure.