The Primary Structure of the Phase-l Flagellar Protein of Salmonella typhimurium

Salmonella PQrQtyphi B SL 877 was shown to be a suitable source of flagellar protein whose amino acid sequence was determined by the H-l structural gene of Salmonella fyphimurium. Isolated flagellin gave one band at a variety of pH levels in acrylamide gel electrophoresis in the presence of disaggregating agents and contained a small amount of carbohydrate. The amino acid content of this flagellin was determined and the NHp-terminal amino acid was identified as alanine. Analysis of the flagellin by gel filtration on agarose in 6 M guanidine HCl-0.1 M Z-mercaptoethanol and acrylamide gel electrophoresis in 0.1% sodium dodecyl sulfate both indicated a molecular weight of 49,000 for the protein, a value not in agreement with previous suggestions. Digestion of the flagellin with trypsin was performed in the presence of 2 M urea, and 29 peptides were isolated from the resulting digest by combinations of column and paper chromatography. The combined amino acid content of the purified peptides corresponded to 46% of the total amino acids present in the molecule (based on a mol wt of 49,000). The amino acid sequence was determined for the peptides isolated and four peptides were found to contain adjacent glycine residues.