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Background: Tryptophanyl-tRNA synthetase (TrpRS) catalyzes activation of tryptophan by ATP and transfer to tRNA Trp , ensuring translation of the genetic code for tryptophan. Interest focuses on mechanisms for specific recognition of both amino acid and tRNA substrates.Results Maximum-entropy methods enabled us to solve the TrpRS structure. Its three parts, a canonical dinucleotide-binding...
Background: Transaldolase is one of the enzymes in the non-oxidative branch of the pentose phosphate pathway. It transfers a C3 ketol fragment from a ketose donor to an aldose acceptor. Transaldolase, together with transketolase, creates a reversible link between the pentose phosphate pathway and glycolysis. The enzyme is of considerable interest as a catalyst in stereospecific organic synthesis and...
Background: Protein evolution gives rise to families of structurally related proteins, within which sequence identities can be extremely low. As a result, structure-based classifications can be effective at identifying unanticipated relationships in known structures and in optimal cases function can also be assigned. The ever increasing number of known protein structures is too large to classify all...
Background: Glutathione S-transferases (GSTs) are a multifunctional group of enzymes, widely distributed in aerobic organisms, that have a critical role in the cellular detoxification process. Unlike their mammalian counterparts, bacterial GSTs often catalyze quite specific reactions, suggesting that their roles in bacteria might be different. The GST from Proteus mirabilis (PmGST B1-1) is known to...
Background: The actin-binding site of several cytoskeletal proteins is comprised of two calponin homology (CH) domains in a tandem arrangement. As a single copy, the CH domain is also found in regulatory proteins in muscle and in signal-transduction proteins. The three-dimensional structures of three CH domains are known, but they have not yet clarified the molecular details of the interaction between...
Background: Parvoviruses infect vertebrates, insects and crustaceans. Many arthropod parvoviruses (densoviruses) are highly pathogenic and kill approximately 90% of the host larvae within days, making them potentially effective as selective pesticides. Improved understanding of densoviral structure and function is therefore desirable. There are four different initiation sites for translation of the...
Background: Several methods of structural classification have been developed to introduce some order to the large amount of data present in the Protein Data Bank. Such methods facilitate structural comparisons and provide a greater understanding of structure and function. The most widely used and comprehensive databases are SCOP, CATH and FSSP, which represent three unique methods of classifying protein...
Background: Are folding pathways conserved in protein families? To test this explicitly and ask to what extent structure specifies folding pathways requires comparison of proteins with a common fold. Our strategy is to choose members of a highly diverse protein family with no conservation of function and little or no sequence identity, but with structures that are essentially the same. The immunoglobulin-like...
Background: β-Keto acyl carrier protein reductase (BKR) catalyzes the pyridine-nucleotide-dependent reduction of a 3-oxoacyl form of acyl carrier protein (ACP), the first reductive step in de novo fatty acid biosynthesis and a reaction often performed in polyketide biosynthesis. The Brassica napus BKR enzyme is NADPH-dependent and forms part of a dissociable type II fatty acid synthetase (FAS). Significant...
Background: Maltose phosphorylase (MP) is a dimeric enzyme that catalyzes the conversion of maltose and inorganic phosphate into β-D-glucose-1-phosphate and glucose without requiring any cofactors, such as pyridoxal phosphate. The enzyme is part of operons that are involved in maltose/malto-oligosaccharide metabolism. Maltose phosphorylases have been classified in family 65 of the glycoside hydrolases...
Methylaspartate ammonia lyase (MAL) catalyzes the magnesium-dependent reversible α,β-elimination of ammonia from L-threo-(2S,3S)-3-methylaspartic acid to mesaconic acid. The 1.3 A MAD crystal structure of the dimeric Citrobacter amalonaticus MAL shows that each subunit comprises two domains, one of which adopts the classical TIM barrel fold, with the active site at the C-terminal end of the barrel...
To improve our understanding of the evolution of novel functions, we performed a sequence, structural, and functional analysis of homologous enzymes and nonenzymes of known three-dimensional structure. In most examples identified, the nonenzyme is derived from an ancestral catalytic precursor (as opposed to the reverse evolutionary scenario, nonenzyme to enzyme), and the active site pocket has been...
Proteins have evolved to balance efficient binding of desired partners with rejection of unwanted interactions. To investigate the evolution of protein-protein interactions, we selected a random library of pre-stabilized TEM1 β-lactamase against wild-type TEM1 using yeast surface display. Three mutations were sufficient to achieve micromolar affinity binding between the two. The X-ray structure emphasized...
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