Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Biophysical Sciences 205of the plasma proteins with different percentages of ammonium sulfate to preferentially depleteserum albumin and subsequently visualize more spots in the proteomic profiles.Sutapa Saha, Dipankar Bhattacharya, Subrata Banerjee, Debashis Banerjee†, Sharmila Chandra†,Abhijit ChakrabartiSG6.1.1.17 Leukemia: a defect in “growing up”We are involved in understanding the role of cell cycle proliferation, the self renewal pathwaysin controlling differentiation or“growing up” of human hematopoietic stem cells. We have earlierdeveloped a mini EBV vector which carries small interfering RNA(siRNA) for the BCR-ABL geneinvolved in chronic myeloid leukemia. This vector has now been further engineered to transfervarious cell cycle genes and cell signalling molecules into hematopoietic stem cells (CD34+) grownin vitro. The role of the immune system in controlling such aberrant proliferation is being studiedin leukemia and various other cancers. Transcriptional regulation of HLA class I gene by variousmiRNA and human EBV genes are being investigated in mesenchymal-epithelial transition of cancerand its invasiveness.Amitava Sengupta, Subrata BanerjeeSG6.1.2 Macromolecular Crystallography6.1.2.1 A high resolution crystal structure of cyclophilin from Leishmania donovani:Elucidation of its interactions with drugs and proteinsThe crystal structure of cyclophilin from Leishmania donovani (LdCyp) has been determined andrefined at 1.97 esolution to a crystallographic R factor of 0.178 (Rfree = 0.197). The structure wassolved by molecular replacement using cyclophilin from Trypanosoma cruzi as the search model.LdCyp exhibits complete structural conservation of the cyclosporin-binding site with respect to thehomologous human protein, as anticipated from LdCyp-cyclosporin binding studies. Comparisonswith other cyclophilins show deviations primarily in the loop regions. The solvent structure encompassingthe molecule has also been analyzed in some detail. The coordinates of this high resolutionstructure were used to build homology models of different mutants to elucidate its interaction with