Comparative studies of flagella from Proteus species

Abstract

Certain aspects of the flagella and flagellar proteins of selected members of the Proteus and Providence groups have been compared. Proteus flagella, negatively stained and examined in the electron microscope, presented both "beaded" and "lined" surface appearance. Structures which possibly represent cross sections of flagella were observed; these show two groups of three sub-units with a slight gap between the triplets. Reaggregation of flagellin occurred in the presence of high concentrations of salt. Purified flagellins of P. vulgaris, P. mirabilis, P. morganii and P. rettgerii and the Providence group gave single bands when electro-phoresed in starch or polyacrylamide gels. Comparison of the mobility of purified flagellins revealed great differences, even between those flagellins isolated from strains of a single accepted species. In addition, tryptic peptide maps of purified flagellins each had a distinctive pattern. Molecular weights of flagellins of the four Proteus species were assessed by electrophoresis jui polyacrylamide gels containing SDS; in all cases values of about 40,000 were obtained. Anri no acid analysis revealed the presence of N-methyl lysine and histidine; neither have been reported conclusively in this group before. N-methyl lysine was restricted to flagellins from certain P. morganii strains while histidine was found in approximately half of the flagellins examined, irrespective of species. The C terminal amino acid of all the flagellins examined is arginine; the C terminal sequence is ser - leu - leu - arg COOH. In every case alanine is the common N terminal amino acid. Seven out of thirty-three of the peptides found on tryptic peptide maps of P. vulgaris NCTG 100 20 flagellin have been completely or partially sequenced. The possibilities of using cyanogen bromide to cleave Proteus flagellin were investigated; citraconylation and maleylation were both extremely effective in keeping the resultant cyanogen bromide fragments in solution. The results are discussed with regard to inter-relationships between the species and the possible uses of these results in the taxonomy of the genus Proteus and the Providence group.