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Identification and characterization of a surface-associated, subtilisin-like serine protease in Trichomonas vaginalis

Published online by Cambridge University Press:  06 July 2010

PABLO HERNÁNDEZ-ROMANO ,
ROBERTO HERNÁNDEZ ,
ROSSANA ARROYO ,
JOHN F. ALDERETE  and
IMELDA LÓPEZ-VILLASEÑOR
PABLO HERNÁNDEZ-ROMANO
Affiliation:
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, 04510 México D.F., México
ROBERTO HERNÁNDEZ
Affiliation:
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, 04510 México D.F., México
ROSSANA ARROYO
Affiliation:
Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), México D.F., México
JOHN F. ALDERETE
Affiliation:
School of Molecular Biosciences, Washington State University, Pullman, WA, USA.
IMELDA LÓPEZ-VILLASEÑOR*
Affiliation:
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, 04510 México D.F., México
*
*Corresponding author: Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, 04510 México D.F., México. Tel: +52 55-56228952. Fax: +52 55-56229212. E-mail: [email protected]
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Summary

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 (~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.

Keywords

Trichomonas vaginalisserine proteasesurface proteincellular localizationsubtilisin
Type
Research Article
Information
Parasitology , Volume 137 , Issue 11 , September 2010 , pp. 1621 - 1635
Copyright
Copyright © Cambridge University Press 2010

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