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The structure of γδ resolvase with a 34 base pair oligonucleotide reveals an intricate and novel complex of the protein with DNA and lays the foundations for understanding transposition at the atomic level.
Background: The three-dimensional structures of histidine-containing phosphocarrier protein (HPr), a member of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), have been determined from Gram-negative and Gram-positive bacteria. The structure of HPr reported here for Mycoplasma capricolum is the first protein structure to be determined for this class of organism. Comparative structural...
Background: Staphylococcus aureus enterotoxin C2 (SEC2) belongs to a family of proteins, termed 'superantigens', that form complexes with class II MHC molecules enabling them to activate a substantial number of T cells. Although superantigens seem to act by a common mechanism, they vary in many of their specific interactions and biological properties. Comparison of the structure of SEC2 with those...
Background: The ribosome - essential for protein synthesis in all organisms - has been an evasive target for structural studies. The best available structures for the 70S Escherichia coli ribosome or its 30S and 50S subunits are based on electron microscopical tilt experiments and are limited in resolution to 28-55 a. The angular reconstitution approach, which exploits the random orientations of particles...
Background: The P4 strain of the corn smut fungus, Ustilago maydis, secretes a fungal toxin, KP4, encoded by a fungal virus (UMV4) that persistently infects its cells. UMV4, unlike most other (non-fungal) viruses, does not spread to uninfected cells by release into the extracellular milieu during its normal life cycle and is thus dependent upon host survival for replication. In symbiosis with the...
The crystal structures of 14-3-3 proteins reveal that they form dimers with a deep groove running along the length of the dimer. The location of conserved residues in this groove suggests that it plays an essential role in the adaptor functions of these proteins.
Background: The polypeptide anthopleurin-B (AP-B) is one of a number of related toxins produced by sea anemones. AP-B delays inactivation of the voltage-gated sodium channel of excitable tissue. In the mammalian heart, this effect is manifest as an increase in the force of contraction. As a result, there is interest in exploiting the anthopleurins as lead compounds in the design of novel cardiac stimulants...
Background: Synchrotron radiation sources have made impressive contributions to macromolecular crystallography. The delay in development of appropriate X-ray detectors has, however, been a significant limitation to their efficient use. New technologies, based on charge-coupled devices (CCDs), provide capabilities for faster, more accurate, automated data collection.Results A CCD-based X-ray detector...
Background: The thrombolytic serine protease tissue-type plasminogen activator (t-PA) is a classical modular protein consisting of three types of domain in addition to the serine protease domain: F1 (homologous to fibronectin type I); G (epidermal growth factor-like) and kringle. Biochemical data suggest that the F1 and G modules play a major role in the binding of t-PA to fibrin and to receptors...
Background: β-glucosidases occur in a variety of organisms and catalyze the hydrolysis of aryl and alkyl-β-D-glucosides as well as glucosides with only a carbohydrate moiety (such as cellobiose). The cyanogenic β-glucosidase from white clover (subsequently referred to as CBG) is responsible for the cleavage of cyanoglucosides. Both CBG and the cyanoglucosides occur within the plant cell wall where...
Background: The collagen triple helix is a unique protein motif defined by the supercoiling of three polypeptide chains in a polyproline II conformation. It is a major domain of all collagen proteins and is also reported to exist in proteins with host defense function and in several membrane proteins. The triple-helical domain has distinctive properties. Collagen requires a high proportion of the...
Background: Leucine-rich repeats (LRRs) are present in proteins with diverse functions. The horseshoe-shaped structure of a ribonuclease inhibitor (RI), with a parallel β sheet lining the inner circumference of the horseshoe and α helices flanking its outer circumference, is the only X-ray structure containing these repeats to be determined. Despite the fact that the lengths and sequences of the RI...
Background: Cellulases are glycosyl hydrolases — enzymes that hydrolyze glycosidic bonds. They have been widely studied using biochemical and microbiological techniques and have attracted industrial interest because of their potential in biomass conversion and in the paper and textile industries. Glycosyl hydrolases have lately been assigned to specific families on the basis of similarities in their...
Background: The enzyme 6-phospho-β-galactosidase hydrolyzes phospholactose, the product of a phosphoenolpyruvate-dependent phosphotransferase system. It belongs to glycosidase family 1 and no structure has yet been published for a member of this family. Results The crystal structure of 6-phospho-β-galactosidase was determined at 2.3 å resolution by multiple isomorphous replacement, using the wild-type...
Electron microscopists have made important progress recently in their quest to determine the structure of the ribosome. New insights into the mechanism of protein synthesis are beginning to emerge, and substantial progress is likely in the immediate future.
Background: Reverse transcriptase (RT) converts the single-stranded RNA genome of a retrovirus into a double-stranded DNA copy for integration into the host genome. This process requires ribonuclease H as well as RNA- and DNA-directed DNA polymerase activities. Although the overall organization of HIV-1 RT is known from previously reported crystal structures, no structure of a complex including a...
Background: Enoyl acyl carrier protein reductase (ENR) catalyzes the NAD(P)H-dependent reduction of trans-Δ2-enoyl acyl carrier protein, an essential step in de novo fatty acid biosynthesis. Plants contain both NADH-dependent and separate NADPH-dependent ENR enzymes which form part of the dissociable type II fatty acid synthetase. Highly elevated levels of the NADH-dependent enzyme are found during...
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