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With the recent demonstration that multiwavelength anomalous dispersion (MAD) can provide accurate experimental phases at high resolution, crystallographers have gained a tool with which to study solvation and flexibility in proteins, and a test-bed for the development of crystallographic methods.
Background: In contrast to the myosins of vertebrate skeletal muscle, molluscan myosins are regulated molecules whose enzymatic activity is switched on by the direct binding of Ca 2+ . The head portion (S1) of the molecule consists of a motor domain and a regulatory domain (RD) containing a 'regulatory' and an 'essential' light chain (RLC and ELC, respectively). The structures of scallop...
Background: Nucleoside 2-deoxyribosyltransferase plays an important role in the salvage pathway of nucleotide metabolism in certain organisms, catalyzing the cleavage of β-2'-deoxyribonucleosides and the subsequent transfer of the deoxyribosyl moiety to an acceptor purine or pyrimidine base. The kinetics describe a ping-pong-bi-bi pathway involving the formation of a covalent enzyme-deoxyribose intermediate...
Background: Members of the structurally-related superfamily of enzymes that includes RNase H, RuvC resolvase, MuA transposase, and retroviral integrase require divalent cations for enzymatic activity. So far, cation positions are reported in the X-ray crystal structures of only two of these proteins, E. coli and human immunodeficiency virus 1 (HIV-1) RNase H. Details of the placement of metal ions...
Two new NMR structures describing the complex formed by a peptide from the BIV Tat protein with the TAR RNA provide a significant advance in our understanding of the ways in which peptides interact with specific sites in the major groove of their RNA targets.
The structure of GroES reveals a potential for instability at odds with the idea of a fixed ring whose only flexible regions are at the outer edges. The importance of GroES in chaperoned protein folding is highlighted by evidence that folding substrates are transiently enclosed under the GroES cap.
Background: Molecular chaperonins 60 are cylindrical oligomeric complexes which bind to unfolded proteins and assist in their folding. Studies to identify the location of the protein substrate have produced contradictory results: some suggest that the substrate-binding site is buried within the interior of the complex, whereas others indicate an external (polar) location.Results Small-angle neutron...
Background: The repeating disaccharide and pentapeptide units of the bacterial peptidoglycan layer are connected by a lactyl ether bridge biosynthesized from UDP-N-acetylglucosamine and phosphoenolpyruvate in sequential enol ether transfer and reduction steps catalyzed by MurA and MurB respectively. Knowledge of the structure and mechanism of the MurB enzyme will permit analysis of this unusual enol...
Background: Thymidylate synthase (TS) is critical to DNA synthesis as it catalyzes the rate limiting step in the only biosynthetic pathway for deoxythymidine monophosphate (dTMP) production. TS is therefore an important target for anti-proliferative and anti-cancer drug design. The TS enzymatic mechanism involves the reductive methylation of the substrate, deoxyuridine monophosphate (dUMP), by transfer...
Background: Mouse lung carbonyl reductase (MLCR) is a member of the short-chain dehydrogenase/reductase (SDR) family. Although it uses both NADPH and NADH as coenzymes, the structural basis of its strong preference for NADPH is unknown.Results The crystal structure of the ternary complex of MLCR (with NADPH and 2-propanol) has been determined at 1.8 a resolution. This is the first three-dimensional...
Background: Detailed structural information on ribosomal proteins has increased our understanding of the structure, function and evolution of the ribosome. L14 is one of the most conserved ribosomal proteins and appears to have a central role in the ribonucleoprotein complex. Studies have indicated that L14 occupies a central location between the peptidyl transferase and GTPase regions of the large...
Background: Maltoporin (which is encoded by the lamB gene) facilitates the translocation of maltodextrins across the outer membrane of E. coli. In particular, it is indispensable for the transport of long maltooligosaccharides, as these do not pass through non-specific porins. An understanding of this intriguing capability requires elucidation of the structural basis. Results The crystal structures...
The crystal structure of a 92 kDa fragment of the yeast type II topoisomerase reveals a toroidal structure with a large central cavity that is likely to be involved in the translocation of a DNA duplex during catalysis.
Background: Foot-and-mouth disease virus (FMDV) is an extremely infectious and antigenically diverse picornavirus of cloven-hoofed animals. Strains of the A22 subtype have been reported to change antigenically when adapted to different growth conditions. To investigate the structural basis of this phenomenon we have determined the structures of two variants of an A22 virus. Results The structures...
Background: Adenylate kinases undergo large conformational changes during their catalytic cycle. Because these changes have been studied by comparison of structures from different species, which share approximately one-third of their residues, only rough descriptions have been possible to date. Results We have solved the structure of unligated adenylate kinase from Escherichia coli at 2.2 å resolution...
Background: Murine polyomavirus recognizes (α2,3)-linked α-5-N-acetylneuraminic acid (sialic acid) on the surface of susceptible cells. While all strains bind to straight-chain receptors terminating in (α2,3)-linked sialic acid, some strains also bind to branched oligosaccharides that carry a second, (α2,6)-linked sialic acid. The ability to bind to these branched-chain receptors correlates with a...
Background: The Kunitz-type inhibitor motif is found at the C terminus of the human collagen α3(VI) chain. This 76-residue module (domain C5) was prepared in recombinant form and showed high stability against proteases; however, it lacked any inhibitory activity against trypsin, thrombin, kallikrein and several other proteases. We have undertaken the determination of the three-dimensional (3D) structure...
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