Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

198 Biennial Report 2005-07characterized. Ultra structural changes of nitrogen fixing bacteria by different fertilizerswere studied.6.1 Research Activities6.1.1 Structural Genomics and Proteomics in Human Genetic Disease6.1.1.1 Huntingtin interacting proteins and their interactors: structural and functionalstudiesTo investigate the role of huntingtin (Htt) interacting proteins in Huntington’s disease (HD),we have cloned Hippi (interacts with Htt-interacting protein Hip1), Rab8 (interacts with Httinteractingprotein HYPL) and HYPK (interacts with Htt) in the bacterial expression vectors forstructural studies and mammalian expression vectors for the functional studies. In the cell model ofHD, where exon1 of Htt gene containing 40 glutamines was expressed that enhanced nuclear aggregationand increased apoptosis, expression of HYPK and Rab8 decreased apoptosis. Subsequently,we observed that the nuclear and cytoplasmic aggregates formed by N-terminal Htt were reduced byHYPK. To investigate the mechanism of the inhibition of aggregates and apoptosis by HYPK, weidentified that HYPK, without having any similarity with any known chaperon, exhibited in vitroand in vivo chaperon activity. To investigate the mechanism of enhanced gene expression by HIPPI,we identified that HIPPI can bind to the specific motif AAAGA[G/C]A[A/C/T][TG] present atthe putative upstream sequence of caspase-1, caspase-8, caspase-10 and PARP-1. In addition wehave shown that the pseudo death effector domain (pDED) present at the c-terminal region ofHIPPI actually interacts with the putative promoter sequences. In an attempt to understand thenature of interactions of the pDED domain, we recently cloned, expressed it and preliminary X-raydiffraction data has been collected. Further characterization of the protein is underway.Pritha Majumder, Swasti Raychaudhuri, Manisha Banerjee, Ananyo Choudhury, Ansuman Lahiri,Debashis Mukhopadhyay, Nitai P BhattacharyyaSG6.1.1.2 Interactions of myloid leukemia factor 1 (MLF1), HCG3 and PARP-1 withN-terminal Huntingtin with 83QTo investigate the structural and functional basis of the involvement of myloid leukemia factor 1(MLF1), HCG3, putative chaperone DNAJ family protein, having J domain only and PARP-1 inHD, we generated a cell model of HD. In this cell model, expression of huntingtin exon1 that codes83Q at a stretch increased nuclear and cytoplasmic Htt-aggregates and apoptosis were observed.We identified that MLF1, HCG3 and PARP-1 interact with N-terminal Htt and reduced apoptosis.Different domains of MLF1 and PARP-1 have been cloned and are now being used to identify thespecific domains of the proteins that interact with the N-terminal domain of Htt. Mechanisms bywhich these protein reduced apoptosis are now being investigated.Manisha Banerjee, Rona Banerjee, Nitai P BhattacharyyaSG, C&MB