NUCLEIC ACIDS, PROTEIN SYNTHESIS, AND MOLECULAR GENETICS
Identification and Characterization of a ran Gene Promoter in the Protozoan Pathogen Giardia lamblia *

https://doi.org/10.1074/jbc.274.28.19699Get rights and content
Under a Creative Commons license
open access

The promoter elements that regulate transcription initiation in Giardia lamblia are poorly understood. In this report, the promoter of the Giardia ran gene was studied using a luciferase expression plasmid pRANluc+ to monitor transcription efficiency. An AT-rich sequence spanning −51/−20 relative to the translation start site of the rangene was identified and was found to be required for efficient luciferase expression by deletion and mutation mapping of pRANluc+. The −51/−20 sequence was also sufficient for promoter activity as revealed from studies on a 32-base pair synthetic promoter derived from this region. Deletion mapping of the synthetic promoter revealed two minimal promoter elements, −51/−42 and −30/−20, sufficient for 6- and 30-fold luciferase expression above background, respectively. The transcription start sites onluc+ messenger RNA were determined by the position of the synthetic promoter in the luciferase expression plasmids as shown by primer extension experiments. Results from electrophoretic mobility shift assays revealed multiple DNA-protein complexes upon binding of nuclear proteins with either DNA strand but not the double-stranded DNA derived from the ran promoter. Our results delineate the first promoter sequence of the Giardia gene (ran), which provides an excellent model for future studies on transcription regulation in this protozoan parasite.

Cited by (0)

*

This work was supported by National Science Council Grant NSC88-2314-B001-031 and a grant from Academia Sinica, Taipei, Taiwan, ROC.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.