title: Crystal structure of the YchF protein reveals binding sites for GTP and nucleic acid.
abstract: The bacterial protein encoded by the gene ychF is 1 of 11 universally conserved GTPases and the only one whose function is unknown. The crystal structure determination of YchF was sought to help with the functional assignment of the protein. The YchF protein from Haemophilus influenzae was cloned and expressed, and the crystal structure was determined at 2.4 A resolution. The polypeptide chain is folded into three domains. The N-terminal domain has a mononucleotide binding fold typical for the P-loop NTPases. An 80-residue domain next to it has a pronounced alpha-helical coiled coil. The C-terminal domain features a six-stranded half-barrel that curves around an alpha-helix. The crablike three-domain structure of YchF suggests the binding site for a double-stranded nucleic acid in the cleft between the domains. The structure of the putative GTP-binding site is consistent with the postulated guanine specificity of the protein. Fluorescence measurements have demonstrated the ability of YchF to bind a double-stranded nucleic acid and GTP. Taken together with other experimental data and genomic analysis, these results suggest that YchF may be part of a nucleoprotein complex and may function as a GTP-dependent translation factor.
authors.affiliation: Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute and the National Institute of Standards and Technology, Rockville, Maryland 20850, USA. alexey@carb.nist.gov
authors.forename: Alexey
authors.initials: A
authors.lastname: Teplyakov
authors.forename: Galina
authors.initials: G
authors.lastname: Obmolova
authors.forename: Seung Y
authors.initials: SY
authors.lastname: Chu
authors.forename: John
authors.initials: J
authors.lastname: Toedt
authors.forename: Edward
authors.initials: E
authors.lastname: Eisenstein
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Howard
authors.forename: Gary L
authors.initials: GL
authors.lastname: Gilliland
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006193:Haemophilus influenzae / Q000737:chemistry / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding
chemical_list: D001426:Bacterial Proteins; D006160:Guanosine Triphosphate; D004247:DNA; D020558:GTP Phosphohydrolases