XRAY CRYSTALLOGRAPHY OF PEPTIDE RNA & OLIGOPEPTIDES IMPLICATED IN DIABETES

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Peptide-RNA ComplexThe protein-RNA recognition process is important in understanding its biological role in macromolecular assembly. Protein binding is often accompanied by large-scale rearrangement of RNA structure. Induced RNA structures exhibit non-standard base pairing and stacking in association with changes in the dimension of grooves. In order to understand the diverse structural repertoire of RNA, we have attempted to crystallize a 15-base non-standard RNA hairpin containing a purine-rich penta-loop in complex with a Lambda N antitermination peptide containing 21 amino acid residues(1). Recently very small crystals of this complex are obtained. Leucine Zipper Peptides: CHOP (C/EBP homologous protein) is a member of the C/EBP (C-terminal enhancer binding protein) family. CHOP is thought to participate in regulating cell growth under stressful conditions. CHOP is found in cells as a dimer with other members of the C/EBP family, with hetero-dimerization being strongly preferred to homodimerization(2). We have used a CHOP peptide of 30 to 36 residues in length with several Leucines indicative of a leucine zipper. However, the sequence is different from the known structures of leucine-zipper motif. Putative Leucine Zipper of MODY Gene Product HNF-1Alpha: We have obtained crystals of MODY wild type oligopeptide fragment (33 residues). Crystallization trials with several mutants which are implied in causing diabetes in children are being carried out. We plan to carry out structure determination with the use of synchrotron radiation, since obtaining reasonably complete and high resolution data is difficult on a laboratory x-ray source with small crystals. Since we do not have free access to home source equipment also, we are unable to get any reasonable data set. We solely depend on on your allocation to solve the above structures with very important applications in Structural Biology.