Cloning and sequence analysis of the gene encoding the crystalline surface layer protein of Rickettsia typhi.

The nucleotide sequence of the gene (slpT) encoding the crystalline surface layer protein (SLP) of Rickettsia typhi was determined. The slpT gene consists of 4935 bp coding for a 1645-amino-acid (aa) protein containing a predicted signal peptide at the N terminus. The size of the predicted SLP exceeds the observed size (135 kDa) on SDS-PAGE. The N-terminal aa sequence of the 32-kDa protein of R. typhi reported by Hackstadt et al. [Infect. Immun. 60 (1992) 159-165] was found in the C-terminal portion of the deduced aa sequence, suggesting that the product of slpT is processed into the mature SLP and the 32-kDa protein.