title: The structure of Pyrococcus horikoshii 2'-5' RNA ligase at 1.94 A resolution reveals a possible open form with a wider active-site cleft.
abstract: Bacterial and archaeal 2'-5' RNA ligases, members of the 2H phosphoesterase superfamily, catalyze the linkage of the 5' and 3' exons via a 2'-5'-phosphodiester bond during tRNA-precursor splicing. The crystal structure of the 2'-5' RNA ligase PH0099 from Pyrococcus horikoshii OT3 was solved at 1.94 A resolution (PDB code 1vgj). The molecule has a bilobal alpha+beta arrangement with two antiparallel beta-sheets constituting a V-shaped active-site cleft, as found in other members of the 2H phosphoesterase superfamily. The present structure was significantly different from that determined previously at 2.4 A resolution (PDB code 1vdx) in the active-site cleft; the entrance to the cleft is wider and the active site is easily accessible to the substrate (RNA precursor) in our structure. Structural comparison with the 2'-5' RNA ligase from Thermus thermophilus HB8 also revealed differences in the RNA precursor-binding region. The structural differences in the active-site residues (tetrapeptide motifs H-X-T/S-X) between the members of the 2H phosphoesterase superfamily are discussed.
authors.affiliation: Faculty of Advanced Life Sciences, Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Yong-Gui
authors.initials: YG
authors.lastname: Gao
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Ayuko
authors.initials: A
authors.lastname: Okada
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D011118:Polynucleotide Ligases / Q000737:chemistry*; D043902:Pyrococcus horikoshii / Q000201:enzymology*
chemical_list: D011118:Polynucleotide Ligases