Conservation of the Host-Interacting Proteins Tp0750 and Pallilysin among Treponemes and Restriction of Proteolytic Capacity to Treponema pallidum.
The spirochete Treponema pallidum subsp. pallidum is the causative agent of syphilis, a chronic, sexually transmitted infection characterized by multiple symptomatic and asymptomatic stages. Although several other species in the genus are able to cause or contribute to disease, T. pallidum differs in that it is able to rapidly disseminate via the bloodstream to tissue sites distant from the site of initial infection. It is also the only Treponema species able to cross both the blood-brain and placental barriers. Previously, the T. pallidum proteins, Tp0750 and Tp0751 (also called pallilysin), were shown to degrade host proteins central to blood coagulation and basement membrane integrity, suggesting a role for these proteins in T. pallidum dissemination and tissue invasion. In the present study, we characterized Tp0750 and Tp0751 sequence variation in a diversity of pathogenic and nonpathogenic treponemes. We also determined the proteolytic potential of the orthologs from the less invasive species Treponema denticola and Treponema phagedenis. These analyses showed high levels of sequence similarity among Tp0750 orthologs from pathogenic species. For pallilysin, lower levels of sequence conservation were observed between this protein and orthologs from other treponemes, except for the ortholog from the highly invasive rabbit venereal syphilis-causing Treponema paraluiscuniculi. In vitro host component binding and degradation assays demonstrated that pallilysin and Tp0750 orthologs from the less invasive treponemes tested were not capable of binding or degrading host proteins. The results show that pallilysin and Tp0750 host protein binding and degradative capability is positively correlated with treponemal invasiveness.
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Simon
S
Houston
Department of Biology, University of Victoria, Victoria, British Columbia, Canada.
John S
JS
Taylor
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Yavor
Y
Denchev
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
Rebecca
R
Hof
Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa, USA Department of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Research, Uppsala, Sweden.
Richard L
RL
Zuerner
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada caroc@uvic.ca.
Caroline E
CE
Cameron
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017124:Conserved Sequence; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D059748:Proteolysis; D011817:Rabbits; D016415:Sequence Alignment; D013045:Species Specificity; D013587:Syphilis / Q000378:metabolism* / Q000382:microbiology; D014208:Treponema / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D014210:Treponema pallidum / Q000145:classification / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
D001426:Bacterial Proteins