HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 277, Issue 34, 30942-30949, August 23, 2002

This Article Full Text Full Text (PDF) All Versions of this Article: 277/34/30942    most recent M204337200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Manning, S. K. Articles by Krishna, S. Search for Related Content PubMed PubMed Citation Articles by Manning, S. K. Articles by Krishna, S. Social Bookmarking                      What's this?

Mutational Analysis of the Hexose Transporter of Plasmodium falciparum and Development of a Three-dimensional Model^*

Suzanne K. Manning, Charles Woodrow^§, Felipe A. Zuniga^¶, Pavel Iserovich^¶, Jorge Fischbarg^¶, Abraham I. Louw, and Sanjeev Krishna^§**

From the  Department of Biochemistry, University of Pretoria, Pretoria 0002, South Africa, the ^§ Department of Infectious Diseases, St. George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, United Kingdom, and the Departments of ^¶ Ophthalmology and  Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, New York, New York 10032

Plasmodium falciparum infection kills more than 1 million children annually. Novel drug targets are urgently being sought as multidrug resistance limits the range of treatment options for this protozoan pathogen. PfHT1, the major hexose transporter of P. falciparum is a promising new target. We report detailed structure-function studies on PfHT1 using site-directed mutagenesis approaches on residues located in helix V (Q169N) and helix VII (³⁰²SGL  AGT). Studies with hexose analogues in these mutants have established that hexose recognition and permeation are intimately linked to these helices. A "fructose filter" effect results from the Q169N mutation (abolishing fructose uptake but preserving affinity and transport of glucose, as reported in Woodrow, C. J., Burchmore, R. J. S., and Krishna, S. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 9931-9936). Associated changes in competition for glucose uptake by C-2, C-3, and C-6 glucose analogues compared with native PfHT1 indicate subtle alterations in substrate interaction in this mutant. The K_m values for glucose uptake in helix VII mutants are also similar to native PfHT1. Hydrogen bonding to positions C-5 and C-6 in glucose analogues becomes relatively more important in these mutants compared with native PfHT1. To increase understanding of hexose permeation pathways in PfHT1, we have developed the first three-dimensional model for PfHT1. As predicted for GLUT1, the principal mammalian glucose transporter, PfHT1 contains a main and an auxiliary channel. After modeling, the Q169N mutation leads predominantly to local structural changes, including displacement of neighboring helix IV. The ³⁰²SGL position in helix VII lies in the same plane as Gln-169 in helix V but is also adjacent to the main hexose permeation pathway, consistent with results from experiments mutating this triplet motif. Furthermore, there are obvious structural and functional differences between GLUT1 and PfHT1 that can now be explored in detail using the approaches presented here. The development of specific inhibitors for PfHT1 will also be aided by these insights.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				T. Joet, U. Eckstein-Ludwig, C. Morin, and S. Krishna Validation of the hexose transporter of Plasmodium falciparum as a novel drug target PNAS, June 24, 2003; 100(13): 7476 - 7479. [Abstract] [Full Text] [PDF]