title: Identification and characterization of a surface-associated, subtilisin-like serine protease in Trichomonas vaginalis.
abstract: Trichomonas vaginalis is a protozoan parasite causing trichomonosis, a sexually transmitted infection in humans. This parasite has numerous proteases, most of which are cysteine proteases that appear to be involved in adherence and cytotoxicity of host cells. In this report we identify and characterize a putative subtilisin-like serine protease (SUB1). The sub1 gene encodes a 101-kDa protein. In silico analyses predict signal and pro-peptides at the N-terminus, and a transmembrane helix at the carboxy-terminal region. The sub1 gene was found as single copy by Southern analysis, albeit additional serine protease related genes are annotated in the T. vaginalis genome. The expression of sub1 could only be detected by RT-PCR and Ribonuclease Protection Assays, suggesting a low abundant mRNA. The sub1 gene transcription start site was correctly assigned by RPA. The transcript abundance was found to be modulated by the availability of iron in the growth medium. Antibodies raised to a specific SUB1 peptide recognized a single protein band (approximately 82 kDa) in Western blots, possibly representing the mature form of the protein. Immunofluorescence showed SUB1 on the trichomonad surface, and in dispersed vesicles throughout the cytoplasm. A bioinformatic analysis of genes annotated as serine proteases in the T. vaginalis genome is also presented. To our knowledge this is the first putative serine protease experimentally described for T. vaginalis.
authors.affiliation: Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, 04510 México DF, México.
authors.forename: Pablo
authors.initials: P
authors.lastname: Hernández-Romano
authors.forename: Roberto
authors.initials: R
authors.lastname: Hernández
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.forename: John F
authors.initials: JF
authors.lastname: Alderete
authors.forename: Imelda
authors.initials: I
authors.lastname: López-Villaseñor
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007501:Iron / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D057057:Serine Proteases / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020860:Subtilisin / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014246:Trichomonas vaginalis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D000953:Antigens, Protozoan; D015800:Protozoan Proteins; D007501:Iron; D057057:Serine Proteases; D020860:Subtilisin