Genes coding for tryptophan-rich proteins are transcribed throughout the asexual cycle of Plasmodium falciparum

Abstract

Multigene families are a common feature in Plasmodia spp. and constitute a substantial content of the parasite genome. Here, we analyse the structural organisation and sequence diversity of two further members of the Trp-rich multigene family of P. falciparum. The complete DNA sequence of both genes was determined from a series of laboratory adapted and field isolates. Based on the amino acid sequences, we have termed them tryptophan-rich antigen-3 (TrpA-3) and lysine-tryptophan-rich antigen (LysTrpA). Analysis of the genes using reverse transcriptase-polymerase chain reaction (RT-PCR), showed that both genes are transcribed and that introns are spliced out at predicted positions. Gene expression profiles obtained from microarray analysis indicate that both genes are expressed in the mid-stages of the asexual cycle. In-frame stop codons were detected which interrupted the reading frame of LysTrpA. Whereas the number of the Trp-rich proteins is rather low in P. falciparum, P. chabaudi, P. berghei and P. yoelii, this family seems to have 15 or more members in P. knowlesi and P. vivax.

Artesunate Tolerance in Transgenic Plasmodium falciparum Parasites Overexpressing a Tryptophan-Rich Protein

“…Among these protein sequences, a family of four P. falciparum tryptophan-rich proteins (PF08_0003, PFA0135w, MAL13P1.269, and PF10_0026 [PArt]) is characterized by a tryptophan-rich motif (40). The sequence alignment of 20 PArt homologues allowed the generation of a first HMM profile of the tryptophan-rich motif to which 79 sequences were found to match (see Table S1 in the supplemental material).…”

Expression, Purification, and Characterization of the Immunological Response to a 40-KilodaltonPlasmodium vivaxTryptophan-Rich Antigen

“…Both the antigens are expressed during the erythrocytic stages of the parasite, are translocated to the red cell membrane via caveola vesicle complex, and have the same genomic organization and positionally conserved tryptophan residues. These tryptophanrich molecules are members of the P. vivax multigene family, which are common in Plasmodium species (25). Multigene families are usually a collection of related genes that probably share a common ancestor and might have originated from each other by gene recombination (25).…”

“…These tryptophanrich molecules are members of the P. vivax multigene family, which are common in Plasmodium species (25). Multigene families are usually a collection of related genes that probably share a common ancestor and might have originated from each other by gene recombination (25). Since the similar P. yoelii tryptophan-rich proteins have shown protection in the murine model and hence have been proposed as potential vaccine candidates (8, 9), we analyzed PvTRAg40 for its immunological characterization.…”

Plasmodium vivax Tryptophan-Rich Antigen PvTRAg33.5 Contains Alpha Helical Structure and Multidomain Architecture

“…They play an important role in the host-parasite interaction [4], [5], [6], [7], [8]. Some of them may be involved in reinvasion of the host erythrocytes by the parasite [5].…”