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The proteolytic activity of 11 treponemal strains representing different phylogenetic groups was investigated by SDS–polyacrylamide gel electrophoresis with copolymerised casein, gelatin and fibrinogen as substrates. The activity was specified to be trypsin‐ and chymotrypsin‐like by the cleavage of synthetic substrates BAPNA and SAAPFNA, respectively. Nine strains degrade casein and the synthetic substrate BAPNA. Chymotrypsin‐like activity specifically inhibited by phenylmethylsulfonyl fluoride was found in four treponemes. Southern blot analysis using a Treponema socranskiisubsp. socranskii‐specific prtPprobe confirmed the presence of prtPhomologous genes in these four strains. The internal fragments of the chymotrypsin‐like protease genes were cloned and sequenced after PCR amplification. Here we report the cloning of the complete prtP‐like gene of T. socranskiisubsp. socranskii, an organism shown to possess epidemiologic relevance in periodontitis.

We recently cloned the major outer membrane protein of Treponema maltophilum[Heuner, K., Choi, B.K., Schade, R., Moter, A., Otto, A., Göbel, U.B., J. Bacteriol. 181, 1025–1029]. Here we report the localization of the major sheath protein (Msp)A protein in T. maltophilumby immunogold electron microscopy and its expression. Northern blot analysis revealed that mspAis expressed constitutively as a monocistronic unit. The transcription initiation site of the mspAgene was identified by primer extension analysis. A further screening of a genomic library of T. maltophilumwith an anti‐outer membrane fraction antibody was done. We were able to clone DNA regions of T. maltophilumencoding putative sugar transport operons and putative outer membrane proteins of this oral treponeme which has a high prevalence in periodontal lesions.

Legionella pneumophila, the aetiologic agent of legionnaires' disease, contains a single, monopolar flagellum which is composed of one major subunit, the FlaA protein. Expression studies using a reporter gene fusion of the flaApromoter with the luxABgene revealed that the flaAexpression is not only temperature regulated but is also influenced by the growth phase, the viscosity and the osmolarity of the medium, and by amino acids.

Legionella pneumophila, the aetiologic agent of legionnaires' disease, contains a single, monopolar flagellum which is composed of one major subunit, the FlaA protein. Expression studies using a reporter gene fusion of the flaA promoter with the luxAB gene revealed that the flaA expression is not only temperature regulated but is also influenced by the growth phase, the viscosity and the osmolarity of the medium, and by amino acids.