title: Evolution of Fseg/Cseg dimorphism in region III of the Plasmodium falciparum eba-175 gene.
abstract: The 175-kDa erythrocyte binding antigen (EBA-175) of the malaria parasite Plasmodium falciparum is important for its invasion into human erythrocytes. The primary structure of eba-175 is divided into seven regions, namely I to VII. Region III contains highly divergent dimorphic segments, termed Fseg and Cseg. The allele frequencies of segmental dimorphism within a P. falciparum population have been extensively examined; however, the molecular evolution of segmental dimorphism is not well understood. A comprehensive comparison of nucleotide sequences among 32 P. falciparum eba-175 alleles identified in our previous study, two Plasmodium reichenowi, and one P. gaboni orthologous alleles obtained from the GenBank database was conducted to uncover the origin and evolutionary processes of segmental dimorphism in P. falciparum eba-175. In the eba-175 nucleotide sequence derived from a P. reichenowi CDC strain, both Fseg and Cseg were found in region III, which implies that the original eba-175 gene had both segments, and deletions of F- and C-segments generated Cseg and Fseg alleles, respectively. We also confirmed the presence of allele with Fseg and Cseg in another P. reichenowi strain (SY57), by re-mapping short reads obtained from the GenBank database. On the other hand, the segmental sequence of eba-175 ortholog in P. gaboni was quite diverged from those of the other species, suggesting that the original eba-175 dimorphism of P. falciparum can be traced back to the stem linage of P. falciparum and P. reichenowi. Our findings suggest that Fseg and Cseg alleles are derived from a single eba-175 allele containing both segments in the ancestral population of P. falciparum and P. reichenowi, and that the allelic dimorphism of eba-175 was shaped by the independent emergence of similar dimorphic lineage in different species that has never been observed in any evolutionary mode of allelic dimorphism at other loci in malaria genomes.
authors.affiliation: Department of Human Functional Genomics, Advanced Science Research Promotion Center, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan. Electronic address: hyasukou@proof.ocn.ne.jp.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yasukochi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan. Electronic address: izumin-tky@umin.ac.jp.
authors.forename: Izumi
authors.initials: I
authors.lastname: Naka
authors.affiliation: Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. Electronic address: jintana.pat@mahidol.ac.th.
authors.forename: Jintana
authors.initials: J
authors.lastname: Patarapotikul
authors.affiliation: Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. Electronic address: hathairad.han@mahidol.ac.th.
authors.forename: Hathairad
authors.initials: H
authors.lastname: Hananantachai
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan. Electronic address: juno-tky@umin.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Ohashi
mesh_terms: D000483:Alleles; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D030541:Databases, Genetic; D019143:Evolution, Molecular; D015870:Gene Expression; D006801:Humans; D010802:Phylogeny; D010961:Plasmodium / Q000145:classification / Q000235:genetics*; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics*; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D000953:Antigens, Protozoan; D015800:Protozoan Proteins; C065668:erythrocyte-binding antigen 175, Plasmodium
keywords: Allelic dimorphism; Malaria evolution; Plasmodium falciparum; Plasmodium reichenowi; eba-175