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Glen Spraggon

Publications and source records attributed to Glen Spraggon.

At least 37 records · Page 2Linked to original sources
PubMed2005

Structural insights into enzyme regulation for inositol 1,4,5-trisphosphate 3-kinase B.

D-Myoinositol 1,4,5-trisphophate 3-kinases (IP(3)-3Ks) play important roles in metazoan cellular signaling. It has been demonstrated that mice without a functional version of IP(3)-3K isoform B are deficient in peripheral T-cells, indicating that IP(3)-3KB is essential to the developing immune system. The recent apo IP(3)-3KA structure exhibited a helix at the catalytic domain N-terminus exhibited a helix at the N-terminus of the catalytic domain, with a tryptophan indole moiety mimicking the binding mode of the substrate ATP purine ring, suggesting a mechanism of autoinhibition. Here we present the structure of the complete catalytic domain of IP(3)-3KB, including the CaM binding domain in complex with Mg(2+) and ATP. The crystal structure reveals a homodimeric arrangement of IP(3)-3KB catalytic domains, mediated via an intermolecular antiparallel beta-sheet formed from part of the CaM binding region. Residues from the putative autoinhibitory helix are rearranged into a loop configuration, with extensive interactions with the bound ATP. Mutagenesis of residues from this region reveals that substitution of the putative autoinhibitory tryptophan generates a hyperactive enzyme which retains Ca(2+)/CaM sensitivity. The IP(3)-3KB structure suggests a mechanism of enzyme activation, and raises the possibility that an interaction between IP(3)-3KB molecules may occur as part of the catalytic or regulatory cycle.

Adenosine Triphosphate↗
PubMed2005

Structural characterization of a p-acetylphenylalanyl aminoacyl-tRNA synthetase.

It has been recently shown that orthogonal tRNA/aminoacyl-tRNA synthetase pairs can be evolved to allow genetic incorporation of unnatural amino acids into proteins in both prokaryotes and eukaryotes. Here we describe the crystal structure of an evolved aminoacyl-tRNA synthetase that charges the unnatural amino acid p-acetylphenylalanine. Molecular recognition is due to altered hydrogen bonding and packing interactions with bound substrate that result from changes in both side-chain and backbone conformation.

Amino Acyl-tRNA Synthetases↗
PubMed2004

The site-specific incorporation of p-iodo-L-phenylalanine into proteins for structure determination.

A recently developed method makes it possible to genetically encode unnatural amino acids with diverse physical, chemical or biological properties in Escherichia coli and yeast. We now show that this technology can be used to efficiently and site-specifically incorporate p-iodo-L-phenylalanine (iodoPhe) into proteins in response to an amber TAG codon. The selective introduction of the anomalously scattering iodine atom into proteins should facilitate single-wavelength anomalous dispersion experiments on in-house X-ray sources. To illustrate this, we generated a Phe153 --> iodoPhe mutant of bacteriophage T4 lysozyme and determined its crystal structure using considerably less data than are needed for the equivalent experiment with cysteine and methionine. The iodoPhe residue, although present in the hydrophobic core of the protein, did not perturb the protein structure in any meaningful way. The ability to selectively introduce this and other heavy atom-containing amino acids into proteins should facilitate the structural study of proteins.

Amino Acid Substitution↗