Regulation of nuclear translocation of the Myb1 transcription factor by TvCyclophilin 1 in the protozoan parasite Trichomonas vaginalis.
In Trichomonas vaginalis, a Myb1 protein was previously demonstrated to repress transcription of an iron-inducible ap65-1 gene. In this study, a human cyclophilin A homologue, TvCyclophilin 1 (TvCyP1), was identified as a Myb1-binding protein using a bacterial two-hybrid library screening system. The recombinant TvCyP1 exhibited typical peptidyl-prolyl isomerase activity with kcat/Km of ∼7.1 μm(-1) s(-1). In a pulldown assay, the His-tagged Myb1 interacted with a GST-TvCyP1 fusion protein, which had an enzymatic proficiency half that of recombinant TvCyP1. Both the enzymatic proficiency of GST-TvCyP1 and its binding to His-Myb1 were eliminated by mutation of Arg(63) in the catalytic motif or inhibited by cyclosporin A. TvCyP1 was primarily localized to the hydrogenosomes by immunofluorescence assay, but it was also co-purified with Myb1 in certain vesicle fractions from differential and gradient centrifugations. Transgenic cells overexpressing HA-TvCyP1 had a higher level of nuclear Myb1 but a much lower level of Myb1 associated with the vesicles than control and those overexpressing HA-TvCyP1(R63A). Myb1 was detected at a much higher level in the HA-TvCyP1 protein complex than in the HA-TvCyP1(R63A) protein complex immunoprecipitated from P15 and P100, but not S100, fractions of postnuclear lysates. A TvCyP1-binding motif, (105)YGPKWNK(111), was identified in Myb1 in which Gly(106) and Pro(107) were essential for its binding to TvCyP1. Mutation of Gly(106) and Pro(107), respectively, in HA-Myb1 resulted in cytoplasmic retention and elevated nuclear translocation of the overexpressed protein. These results suggest that TvCyP1 may induce the release of Myb1 that is restrained to certain cytoplasmic vesicles prior to its nuclear translocation.
Divisions of Infectious Diseases and Immunology and.
Hong-Ming
HM
Hsu
Divisions of Infectious Diseases and Immunology and From the Department of Parasitology, College of Medicine, National Taiwan University and.
Chien-Hsin
CH
Chu
From the Department of Parasitology, College of Medicine, National Taiwan University and.
Ya-Ting
YT
Wang
Divisions of Infectious Diseases and Immunology and.
Yu
Y
Lee
Structure Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
Shu-Yi
SY
Wei
Divisions of Infectious Diseases and Immunology and.
Hsing-Wei
HW
Liu
From the Department of Parasitology, College of Medicine, National Taiwan University and.
Shiou-Jeng
SJ
Ong
Structure Biology, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
Chinpan
C
Chen
Divisions of Infectious Diseases and Immunology and From the Department of Parasitology, College of Medicine, National Taiwan University and taijh@gate.sinica.edu.tw.
Jung-Hsiang
JH
Tai
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014246:Trichomonas vaginalis / Q000166:cytology* / Q000378:metabolism*
D015800:Protozoan Proteins; D014157:Transcription Factors
Cyclophilin; Membrane Trafficking; Myb1; Nuclear Translocation; Parasitology; Peptidyl-prolyl Isomerase; Protein-Protein Interaction; Transcription Regulation; Trichomonas vaginalis; TvCyP1