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Indian Journal of Medical Microbiology, Vol. 26, No. 3, July-September, 2008, pp. 246-247 Brief Communication Identification of transmembrane region and orientation of aquaglyceroporin of Plasmodium falciparum Wiwanitkit V Department of Clinical Laboratory Medicine, Faculty of Medicine, Wiwanitkit House, Bangkhae, Bangkok 10160 Date of Submission: 17-Aug-2007 Code Number: mb08076 Abstract Aquaglyceroporin is a subclass of aquaporin water channels. This protein is also a focused potential drug target for falciparum malaria. However, the knowledge about the structure of this protein is limited. In this communication, the author performed a study to determine the transmembrane region and orientation of aquaglyceroporin of Plasmodium falciparum . According to this study, six transmembrane regions of aquaglyceroporin of P. falciparum can be identified. These regions can be the focused target for future drug development.Keywords: Aquaglyceroporin, facliparum, tranmembrane The malaria parasite Plasmodium falciparum faces drastic osmotic changes during kidney passages and is engaged in the massive biosynthesis of glycerolipids during its development in the blood-stage. [1] P. falciparum infection induces alterations in the transport properties of infected erythrocytes that have recently been defined using electrophysiological techniques. [2] Mechanisms responsible for transport of substrates into intraerythrocytic parasites have also been clarified by studies of three substrate-specific (hexose, nucleoside and aquaglyceroporin) parasite plasma membrane transporters. [2] Aquaglyceroporin is a subclass of aquaporin water channels. [3] Aquaglyceroporins are also able to transport glycerol and perhaps urea and other small solutes. [3] There is now compelling evidence for involvement of aquaglyceroporin- facilitated glycerol transport in skin hydration and fat cell metabolism. [3] Aquaglyceroporin is also important in the transport process of falciparum malaria. [1],[2] This protein is also a focused potential drug target for falciparum malaria. However, the knowledge about the structure of this protein is limited. Here, the author performed a study to determine the transmembrane region and orientation of aquaglyceroporin of P. falciparum . Materials and Methods First, the sequence of the aquaglyceroporin of P. falciparum was searched from the database, PubMed. Then, the author used a tool namely TMpred for study of the transmembrane region and orientation of aquaglyceroporin of P. falciparum . Basically, the TMpred program makes a prediction of membrane-spanning regions and their orientation. [4] The algorithm is based on the statistical analysis of TMbase, [4] a database of naturally occurring transmembrane proteins. TMbase is mainly based on SwissProt, but contains informations from other sources as well. Important data fields include, for example, the putative transmembrane sequence, the sequence of the flanking regions, taxonomic information, the presumed orientation of the segment, calculated values for hydrophobicity and hydrophobic moment, and grouping into families by either functional or sequence relatedness of the proteins. [4] All data is stored in different tables, suited for use with any relational database management system. [4] The prediction is made using a combination of several weight-matrices for scoring. [4]Results The derived sequence of aquaglyceroporin of P. falciparum from searching is shown in the [Figure - 1] According to the TMpred analysis, the possible transmembrane helices are listed in the table. There are three possible inside to outside helices and four possible outside to inside helices. The pattern of orientation is shown in the table and [Figure - 2].Discussion Falciparum malaria is still an important infection. It infects and replicates in human erythrocytes. Through the use of substrate-specific transport proteins, P. falciparum takes up nutrients from the erythrocyte′s cytoplasm. [5] The sequencing and publishing of the P. falciparum genome have made it possible to identify, clone and characterise a number of these transport proteins from the parasite. [5] The membrane transport proteins become a new target for antimalarial drug development. Aquaglyceroporin is an important malarial membrane protein. The aquaglyceroporin of Plasmodium falciparum is a bi-functional channel with permeability for water and solutes. [6] Its functions supposedly are in osmotic protection of parasites and in facilitation of glycerol permeation for glycerolipid biosynthesis. [6] Beitz et al , reported that the plasmodium aquaglyceroporin in the electrostatic environment at the extracellular pore entry regulates water permeability. [7] Pavlovic-Djuranovic et al , showed aquaglyceroporin of P. falciparum permeability for the glycolysis-related metabolites methylglyoxal, a cytotoxic byproduct, and dihydroxyacetone, a ketotriose. [6] Recently, Promeneur et al , found that plasmodium aquaglyceroporin provides the pathway for glycerol uptake into the malaria parasite. [8] They also found that this played an important role in the blood-stage development of the rodent malaria parasite during infection in mice and could be added to the list of targets for the design of antimalarial drugs. [8] In this work, the transmembrane region and orientation of aquaglyceroporin of P. falciparum was studied. Although there is a previous report on the structure of aquaglyceroporin, it does not involve the malarial type. [9] According to this study, six transmembrane regions of aquaglyceroporin of P. falciparum can be identified. These regions can be the focused target for future drug development. References
Copyright 2008 - Indian Journal of Medical Microbiology The following images related to this document are available:Photo images[mb08076f1.jpg] [mb08076t1.jpg] [mb08076f2.jpg] |
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