title: The structure of TON1937 from archaeon Thermococcus onnurineus NA1 reveals a eukaryotic HEAT-like architecture.
abstract: The members of the ARM/HEAT repeat-containing protein superfamily in eukaryotes have been known to mediate protein-protein interactions by using their concave surface. However, little is known about the ARM/HEAT repeat proteins in prokaryotes. Here we report the crystal structure of TON1937, a hypothetical protein from the hyperthermophilic archaeon Thermococcus onnurineus NA1. The structure reveals a crescent-shaped molecule composed of a double layer of α-helices with seven anti-parallel α-helical repeats. A structure-based sequence alignment of the α-helical repeats identified a conserved pattern of hydrophobic or aliphatic residues reminiscent of the consensus sequence of eukaryotic HEAT repeats. The individual repeats of TON1937 also share high structural similarity with the canonical eukaryotic HEAT repeats. In addition, the concave surface of TON1937 is proposed to be its potential binding interface based on this structural comparison and its surface properties. These observations lead us to speculate that the archaeal HEAT-like repeats of TON1937 have evolved to engage in protein-protein interactions in the same manner as eukaryotic HEAT repeats.
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Jae-Hee
authors.initials: JH
authors.lastname: Jeong
authors.forename: Yi-Seul
authors.initials: YS
authors.lastname: Kim
authors.forename: Catleya
authors.initials: C
authors.lastname: Rojviriya
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Cha
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Ha
authors.forename: Yeon-Gil
authors.initials: YG
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D051186:Armadillo Domain Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D016415:Sequence Alignment; D019712:Thermococcus / Q000737:chemistry* / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D051186:Armadillo Domain Proteins; D008024:Ligands; D011994:Recombinant Proteins
keywords: ARM/HEAT repeats; Archaea; Crystal structure; Molecular evolution; Thermococcus onnurineus