Multifarious transcriptional regulation of adhesion protein gene ap65-1 by a novel Myb1 protein in the protozoan parasite Trichomonas vaginalis.
The transcription efficiency of an adhesion protein gene, ap65-1, in Trichomonas vaginalis varies with changes in the iron supply and with the growth stage. In the present study, two Myb recognition elements, MRE-1/MRE-2r and MRE-2f, were found to play antagonistic roles in regulating the iron-inducible activity of an ap65-1 reporter gene. Intriguingly, either of these elements was shown to be sufficient to repress basal activity, but together they were also shown to activate growth-related activity of the reporter gene in iron-depleted cells. A myb1 gene which encodes a 24-kDa protein containing a Myb-like R2R3 DNA binding domain was identified from Southwestern screening of MRE-2f-binding proteins. The Myb1 protein was detected as a major 35-kDa protein which exhibited variations in nuclear concentration with changes in the iron supply. A recombinant Myb1 protein was shown to differentially interact with MRE-1/MRE-2r and MRE-2f in vitro. Overexpression of hemagglutinin-tagged Myb1 in T. vaginalis resulted in repression or activation of ap65-1 transcription in iron-depleted cells at an early and a late stage of cell growth, respectively, while iron-inducible ap65-1 transcription was constitutively repressed. The hemagglutinin-tagged Myb1 protein was found to constantly occupy the chromosomal ap65-1 promoter at a proximal site, but it also selected two more distal sites only at the late growth stage. Together, these observations suggest that Myb1 critically regulates multifarious ap65-1 transcription, possibly via differential selection of multiple promoter sites upon environmental changes.
Ong
Shiou-Jeng
SJ
Division of Infectious Diseases, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
Hsu
Hong-Ming
HM
Liu
Hsing-Wei
HW
Chu
Chien-Hsin
CH
Tai
Jung-Hsiang
JH
D000595:Amino Acid Sequence; D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D017125:Genes, Protozoan / Q000235:genetics*; D007501:Iron / Q000494:pharmacology; D008969:Molecular Sequence Data; D010271:Parasites / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*; D014246:Trichomonas vaginalis / Q000166:cytology / Q000235:genetics*
C096723:AP65-1 protein, Trichomonas vaginalis; D015815:Cell Adhesion Molecules; D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D007501:Iron