title: Functional characterization of the 5' proximal flanking fragment of Plasmodium falciparum GBP130 gene.
abstract: OBJECTIVE
  To identify the putative regulation elements with strength- and stage-specificity in 5' proximal flanking sequence of P. falciparum GBP130 gene.
  
  
  METHODS
  Plasmids containing different deletions of upstream of the GBP130 promoter were constructed. For strength-specific analysis, pGBPCAT delta 2, pGBP delta 2/400 and pGBP delta 2/800 were electroporated into ring-stage P. f. respectively, and the expression level of CAT in each plasmid was detected by liquid scintillation counts(LSC). For stage-specific analysis, transfectants with pGBP delta 2/400 and pGBP delta 2/800 were harvested at 5 hours post-transfection(h), 15 h and 46 h respectively, and the CAT expression levels were detected.
  
  
  RESULTS
  In strength-specific analysis, the expression level of CAT in pGBP delta 2/800 and pGBPCAT delta 2 was similar, down-regulated significantly in pGBP delta 2/400. The CAT level showed significant difference between pGBP delta 2/400 and the control. In stage-specific analysis, the CAT level of pGBP delta 2/400 was higher than that of pGBP delta 2/800 at the time point of 5 h, and lower at 15 h and 46 h.
  
  
  CONCLUSIONS
  This strength-specific promoter activity was due to the difference of 5'UTR length: the longer the 5'UTR the higher the promoter strength, and two poly (dA:dT) tracts in the proximal sequence could enhance the promoter activity. The length of 5'UTR regulated the promoter activity in a stage-specific manner. The shorter 5'UTR was functional at ring stage, while the longer one prompted transcription at trophozoite and schizont stage. The functional role of poly (dA:dT) tracts in stage-specific regulation of GBP130 remains unclear.
authors.affiliation: Department of Etiology, Fourth Military Medical University, Xi'an 710032. wangjn123@yahoo.com
authors.forename: Xian-feng
authors.initials: XF
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Miao
authors.forename: Zhong-xiang
authors.initials: ZX
authors.lastname: Liu
authors.forename: Xun
authors.initials: X
authors.lastname: Li
authors.forename: Rong-fen
authors.initials: RF
authors.lastname: Zhen
authors.forename: Cai-fang
authors.initials: CF
authors.lastname: Xue
mesh_terms: D024506:5' Flanking Region / Q000235:genetics*; D000818:Animals; D015536:Down-Regulation; D006021:Glycophorins / Q000235:genetics*; D010963:Plasmodium falciparum / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics*; D014162:Transfection; D020506:Untranslated Regions / Q000235:genetics
chemical_list: D006021:Glycophorins; D015800:Protozoan Proteins; D020506:Untranslated Regions