Date of Award

2013

Degree Type

Thesis

Department

Biological, Geological and Environmental Sciences

First Advisor

Sam-Yellowe, Tobili Y.

Subject Headings

Bioinformatics, Malaria, Host-parasite relationships, Ribonucleases, Plasmodium falciparum, Proteins, Biology

Abstract

Malaria caused by the parasite Plasmodium, still remains a significant public health problem worldwide, due to lack of a vaccine and emerging drug and insecticide resistance, among malaria parasites and mosquito vectors, respectively. Rhoptry proteins of Plasmodium enable merozoite invasion of host erythrocytes. However, only a few of these proteins have been characterized. Thirty-six P. yoelii merozoite rhoptry proteins were identified as putative rhoptry proteins by proteome analysis. Some of these proteins have been characterized while others still remain an intense area of active research. Molecular characterization and understanding of these novel proteins may assist in vaccine development, design of diagnostic assays and better control of malaria disease. This study was aimed at characterizing two Plasmodium rhoptry genes Translocon and Ribonuclease binding-like (RNB-like) genes using bioinformatics analysis and in vitro cell free expression. Bioinformatics analysis was performed using the databases: PlasmoDB, ExPaSy, PSORTb, SWISSPROT-workspace, GeneDB, National Center for Biotechnology Information (NCBI) and COBALT: Multiple Alignment Tool. Both genes were characterized for features such as conservation profiles, domain architecture and alignment of sequences, both within Plasmodium species and among members of the phylum apicomplexa. The RNB protein domains are generally conserved across Plasmodium species but protein identity across species is 30 . The amino acid identity is about 40 across species for the Translocon protein. This study revealed that these genes are expressed early upon merozoite invasion of the host erythrocytes. The expressed translocon protein that is annotated as hypothetical or putative has been shown to be part of a transport complex and the RibonucleaRibonuclea Ribonuclease binding binding -like (RNB) gene expresses a putative RNB -like protein found in all species of Plasmodium . The translocon of Plasmodium falciparum was successfully PCR amplified, cloned and a 2

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