title: Crystal structure of the PIN domain of human telomerase-associated protein EST1A.
abstract: Saccharomyces cerevisiae Est1p is a telomerase-associated protein essential for telomere length homeostasis. hEST1A is one of the three human Est1p homologues and is considered to be involved not only in regulation of telomere elongation or capping but also in nonsense-mediated degradation of RNA. hEST1A is composed of two conserved regions, Est1p homology and PIN (PilT N-terminus) domains. The present study shows the crystal structure of the PIN domain at 1.8 A resolution. The overall structure is composed of an alpha/beta fold or a core structure similar to the counterpart of 5' nucleases and an extended structure absent from archaeal PIN-domain proteins and 5' nucleases. The structural properties of the PIN domain indicate its putative active center consisting of invariant acidic amino acid residues, which is geometrically similar to the active center of 5' nucleases and an archaeal PAE2754 PIN-domain protein associated with exonuclease activity.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Daijiro
authors.initials: D
authors.lastname: Takeshita
authors.forename: Shuhei
authors.initials: S
authors.lastname: Zenno
authors.forename: Woo Cheol
authors.initials: WC
authors.lastname: Lee
authors.forename: Kaoru
authors.initials: K
authors.lastname: Saigo
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanokura
mesh_terms: D019943:Amino Acid Substitution; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012680:Sensitivity and Specificity; D019098:Telomerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004722:Endoribonucleases
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D011994:Recombinant Proteins; D019098:Telomerase; C512261:SMG6 protein, human; D004722:Endoribonucleases