Project description:<p>The overall goal of this proposed project is to identify rare genetic variants contributing to childhood onset-Crohn disease. Crohn disease is a chronic inflammatory disorder of the gastrointestinal tract of unclear etiology and no known cure. Affected children suffer from diarrhea, abdominal pain, growth disturbances, and an impaired quality of life. The identified Crohn disease susceptibility alleles have improved our understanding of Crohn disease pathogenesis. However, the identified susceptibility alleles do not account for the observed heritability, nor have disease-causing alleles in many genomic regions been identified. For the proposed studies, we will use 1) existing DNA samples collected from high-risk Crohn kindreds identified using the extensive genealogical records available only in Utah, 2) existing DNA samples obtained from very young children with Crohn disease and their parents, and 3) existing DNA samples obtained from healthy controls that are free of a personal or family history of autoimmune disorders.</p>

| phs000926 | dbGaP

Homo sapiens

Project description:Rare germline copy number variations and disease susceptibility in familial melanoma

| PRJNA336003 | ENA

Crystal structure of Homo sapiens kynureninase.

Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.

| S-EPMC2531291 | biostudies-literature