Book of Abstracts: Albany 2007
June 19-23 2007
Structural Genomics of Plasmodium falciparum and Related Apicomplexan Organisms
Malaria, toxoplasmosis, and cryptosporidiosis are examples of deadly tropical diseases without effective treatment, particularly in economically under-developed regions of the world. Advances in vaccine development and drug discovery are urgently needed to control these diseases and can be facilitated by production of purified recombinant proteins from Apicomplexan genomes and determination of their 3D structures. In spite of emerging genome sequencing and annotation data in the last few years, both heterologous expression and crystallization of Apicomplexan proteins have seen only limited success. In an effort to explore the effectiveness of producing and crystallizing proteins on a genome scale using a standardized methodology, 380 distinct Plasmodium falciparum target genes were chosen representing different cellular classes, along with select orthologues from four other Plasmodium species as well as Cryptosporidium parvum and Toxoplasma gondii. From a total of 1,022 genes from the seven genomes, 313 (24.2%) produced purified soluble proteins and 102 (10.0%) crystallized, culminating in 36 crystal structures. These results demonstrate that, contrary to previous findings, a standardized platform using E. coli can be effective for genome scale production and crystallography of Apicomplexan proteins. Predictably, orthologous proteins from different Apicomplexan genomes behaved differently in expression, purification, and crystallization. These differences were effectively exploited to elevate the overall productivity to levels comparable to the most successful ongoing structural genomics projects: 236 of the 469 target genes produced purified soluble protein from one or more organisms, with 84 and 33 of the purified targets respectively leading to crystals and ultimately structures.
The structures obtained in this project enable us to conduct structural comparison between Apicomplexan proteins and human homologues (and homologues from other organisms). This study is leading to, for example, functional implications about differences in the biosynthesis of pyrimidines and isoprenoids, not just between parasites and humans, but also amongst Apicomplexan parasites.
Structural Genomics Consortium