A major impediment to the use of adenovirus as a gene therapy vector and for vaccine applications is the host immune response to adenovirus hexon-the major protein component of the icosahedral capsid. A solution may lie in novel vectors with modified or chimeric hexons designed to evade the immune response. To facilitate this approach, we have distinguished the portion of hexon that all serotypes have in common from the hypervariable regions that are responsible for capsid diversity and type-specific immunogenicity. The common hexon core-conserved because it forms the viral capsid-sets boundaries to the regions where modifications can be made to produce nonnative hexons. The core has been defined from the large and diverse set of known hexon sequences by an accurate alignment based on the newly refined crystal structures of human adenovirus types 2 (Ad2) and Ad5 hexon. Comparison of the two hexon models, which are the most accurate so far, reveals that over 90% of the residues in each have three-dimensional positions that closely match. Structures for more distant hexons were predicted by building molecular models of human Ad4, chimpanzee adenovirus (AdC68), and fowl adenovirus 1 (FAV1 or CELO). The five structures were then used to guide the alignment of the 40 full-length (>900 residues) hexon sequences in public databases. Distance-and parsimony-based phylogenetic trees are consistent and reveal evolutionary relationships between adenovirus types that parallel those of their animal hosts. The combination of crystallography, molecular modeling, and phylogenetic analysis defines a conserved molecular core that can serve as the armature for the directed design of novel hexons.
Hexokinase is the first enzyme in the glycolytic pathway, catalyzing the transfer of a phosphoryl group from ATP to glucose to form glucose 6-phosphate and ADP. Two yeast hexokinase isozymes are known, namely PI and PII. The crystal structure of yeast hexokinase PII from Saccharomyces cerevisiae without substrate or competitive inhibitor is determined and refined in a tetragonal crystal form at 2.2-Å resolution. The folding of the peptide chain is very similar to that of Schistosoma mansoni and previous yeast hexokinase models despite only 30% sequence identity between them. Distinct differences in conformation are found that account for the absence of glucose in the binding site. Comparison of the current model with S. mansoni and yeast hexokinase PI structures both complexed with glucose shows in atomic detail the rigid body domain closure and specific loop movements as glucose binds. A hydrophobic channel formed by strictly conserved hydrophobic residues in the small domain of the hexokinase is identified. The channel's mouth is close to the active site and passes through the small domain to its surface. The possible role of the observed channel in proton transfer is discussed.
Hexokinase is the first enzyme in the glycolytic pathway that catalyzes the transfer of a phosphoryl group from ATP to glucose to form glucose-6-phosphate and ADP. Two yeast hexokinase isozymes are known, namely PI and PII. Here we redetermined the crystal structure of yeast hexokinase PI from Saccharomyces cerevisiae as a complex with its substrate, glucose, and refined it at 2.95 A resolution. Comparison of the holo-PI yeast hexokinase and apo-hexokinase structures shows in detail the rigid body domain closure and specific loop movements as glucose binds and sheds more light on structural basis of the "induced fit" mechanism of reaction in the HK enzymatic action. We also performed statistical coupling analysis of the hexokinase family, which reveals two co-evolved continuous clusters of amino acid residues and shows that the evolutionary coupled amino acid residues are mostly confined to the active site and the hinge region, further supporting the importance of these parts of the protein for the enzymatic catalysis.
Major urinary proteins belong to the lipocalin family and are present in the urine of rodents as an ensemble of isoforms with pheromonal activity. The crystal structure of a recombinant mouse MUP (rMUP) was solved by the molecular‐replacement technique and refined to an R factor and Rfree of 20 and 26.5%, respectively, at 1.75 Å resolution. The structure was compared with an NMR model and with a crystallographic structure of the wild‐type form of the protein. The crystal structures determined in different space groups present significantly smaller conformational differences amongst themselves than in comparison with NMR models. Some, but not all, of the conformational differences between the crystal and solution structures can be explained by the influence of crystallographic contacts. Most of the differences between the NMR and X‐ray structures were found in the N‐terminus and loop regions. A number of side chains lining the hydrophobic pocket of the molecule are more tightly packed in the NMR structure than in the crystallographic model. Surprisingly, clear and continuous electron density for a ligand was observed inside the hydrophobic pocket of this recombinant protein. Conformation of the ligand modelled inside the density is coherent with the results of recent NMR experiments.
JavaProtein Dossier ( J PD) is a new concept, database and visualization tool providing one of the largest collections of the physicochemical parameters describing proteins' structure, stability, function and interaction with other macromolecules. By collecting as many descriptors/parameters as possible within a single database, we can achieve a better use of the available data and information. Furthermore, data grouping allows us to generate different parameters with the potential to provide new insights into the sequence-structure-function relationship. In J PD, residue selection can be performed according to multiple criteria. J PD can simultaneously display and analyze all the physicochemical parameters of any pair of structures, using precalculated structural alignments, allowing direct parameter comparison at corresponding amino acid positions among homologous structures. In order to focus on the physicochemical (and consequently pharmacological) profile of proteins, visualization tools (showing the structure and structural parameters) also had to be optimized. Our response to this challenge was the use of Java technology with its exceptional level of interactivity. J PD is freely accessible (within the Gold Sting Suite) at
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