Major research activities in this
laboratory focus on studying the regulation of gene transcription in two
important human protozoan pathogens Giardia lamblia and Trichomonas
vaginalis, both of which are also recognized to be among the earliest
evolved eukaryotic cells. In the past few years, we established DNA transfection
systems (1, 4, 8) and characterized DNA regulatory elements of selected genes
(3, 7, 8) in each of these organisms. We found that G. lamblia uses
multiple copies of a simple T-tract element as core promoter as well as distal
activator in a manner quite distinct from other eukaryotes or prokaryotes (3,
7). In T. vaginalis, distinct sets of promoter elements and their
associated nuclear proteins, which regulate basal and iron-inducible
transcription of the
gene, were identified and characterized (8). Southwestern screening of a cDNA
expression library resulted in cloning of four MYB-like transcription factors
and a single stranded DNA-binding protein p38. Biochemical properties and
functions of these proteins are under investigation. Molecular cloning of the
iron-inducible nuclear proteins, which may be responsible for iron-induced gene
expression in T. vaginalis, is being conducted. Our future directions
will focus on basal transcription machinery in G. lamblia and
iron-induced transcriptional regulation in T. vaginalis. These studies
will broaden our knowledge on transcriptional regulation operating in lower
- Sun, C.H., Chou, C.F. and Tai, J.H. (1998). Stable DNA transfection in the pathogenic protozoan
Giardia lamblia. Mol. Biochem. Parasitol. 92: 123-132.
- Liu, H.W., Chu, Y.D. and Tai, J.H.
(1998). Characterization of Trichomonas vaginalis virus
proteins in the pathogenic protozoan T. vaginalis. Arch. Virol. 143: 963-970.
- Sun, C.H. and Tai, J.H.
(1999). Identification and characterization of a ran gene promoter in the
protozoan pathogen Giardia lamblia. J. Biol. Chem. 274: 19699-19706.
- Sun, C.H. and Tai, J.H.
(2000). Development of a tetracycline-controlled gene expression system in the
parasitic protozoan Giardia lamblia. Mol. Biochem. Parasitol. 105: 51-60.
- Bessarab, I. N., Liu, H.
S., Ip, C. F. and Tai, J.H. (2000). The complete cDNA sequence of a type
II Trichomonas vaginalis Virus. Virology 267: 350-359.
- Ong, J. J. and Tai,
J.H. (2000). Identification of virus-specific vesicles in Giardiavirus-infected
Giardia lamblia. J. Microbiol. Immunol. Infect.33: 9-13.
- Ong, S.J., Huang, L.C.,
Liu, H.W., Chang, S.C., Bessarab, I., Yang, Y.C. and Tai, J.H. (2002).
Characterization of a bi-directional promoter for divergent transcription of a
PHD-zinc finger protein gene and a ran gene in the protozoan pathogen Giardia
lamblia. Mol. Microb. 43(3): 665-676.
- Tsai, C.D., Liu, H.W. and Tai, J.H.(2002). Characterization of an iron-responsive promoter in the
protozoan pathogen Trichomonas vaginalis. J. Biol. Chem. 277: 5153-5162.
- Ong, S. J., Huang, S. C.,
Liu, H. W. , and Tai , J. H. (2004). Involvement of multiple DNA
elements in iron-inducible transcription of the ap65-1 gene in the protozoan
parasite Trichomonas vaginalis. Mol. Microbiol. 52(6):1721-1730.