02072nas a2200205   4500008004100000022001500041245010100056210006900157260000800226300001400234490000800248520136500256100002201621700001901643700001901662700001901681700002501700700002101725856012001746       2018                        eng d  a 0141-813000aActivation of HRI is mediated by Hsp90 during stress through modulation of the HRI-Hsp90 complex0 aActivation of HRI is mediated by Hsp90 during stress through mod  cOCT  a1604-16130 v1183 aHeme Regulated Inhibitor (HRI) is known to get activated in various stresses such as heme deficiency, heat shock, heavy metal toxicity etc. Heat shock protein 90 (Hsp90), a ubiquitous cytoplasmic protein interacts with HRI in order to regulate protein synthesis. However, it still remains to establish this interaction of HRI and Hsp90 at cellular levels and how this modulation of HRI activity is mediated by Hsp90 during stress. In the present report, using co-immunoprecipitation analysis we show that HRI interacts with Hsp90 and this association is independent of other co-chaperones in in vitro conditions. Further, analysis using truncated domains of HRI revealed that the K1 subdomain is essential for HRI - Hsp90 complex formation. Our in silico protein - protein interaction studies also indicated interaction of Hsp90 with K1 subdomain of HRI. Mammalian two hybrid assay validated this HRI - Hsp90 interaction at cellular levels. When the in vitro kinase assay was carried out with the co-immunoprecipitated complex of HRI - Hsp90, an increase in the kinase activity was observed resulting elevated levels of eIF2 alpha phosphorylation upon heavy metal stress and heat shock. Thus, our results clearly indicate modulation of HRI kinase activity with simultaneous Hsp90 association under stress conditions. (C) 2018 Elsevier B.V. All rights reserved.1 aBerwal, Sunil, K.1 aBhatia, Varsha1 aBendre, Arneya1 aSuresh, C., G.1 aChatterjee, Sangeeta1 aPal, Jayanta, K.  uhttps://library.ncl.res.in/content/activation-hri-mediated-hsp90-during-stress-through-modulation-hri-hsp90-complex02188nas a2200217   4500008004100000022001500041245008900056210006900145260000800214300001200222490000800234520147700242100002001719700001701739700001901756700001901775700002501794700001501819700002101834856011501855       2018                        eng d  a 0141-813000aThe Leishmania donovani IMPACT-like protein possesses non-specific nuclease activity0 aLeishmania donovani IMPACTlike protein possesses nonspecific nuc  cNOV  a962-9730 v1193 aIMPACT (Imprinted and Ancient)-like proteins are known to be regulators of GCN2 (General control non-derepressible 2) kinases involved in translation regulation. Here, we report on cloning and characterization of an IMPACT-like protein, LdIMPACT from Leishmania donovani which harbours two domains. 'RWD domain' at the N-terminal end that mediates GCN2 regulation, while a conserved 'ancient domain' lies at the C-terminal end whose function remains elusive. Interestingly, our observations indicated that LdIMPACT has a novel nonspecific nuclease activity. In silico analysis further revealed the resemblance of ancient domain of LdIMPACT to RNase PH domain (known to bind to nucleic acids). The recombinant LdIMPACT exhibited a Mg2+-dependent nuclease activity. Moreover, thermostability and pH stability assays of the protein suggest it to be a stress responsive protein. Circular dichroism studies elucidated the conformational transitions of the enzyme in response to various temperature and pH conditions which correlated well with the activity profiles. Thus, the current study highlights the structural and functional characteristics of LdIMPACT which interestingly also possesses a novel nuclease activity. With its physiological relevance unresolved, the multifaceted LdIMPACT might therefore lie in a hitherto unknown network, whose perturbation could be an attractive therapeutic approach for treating leishmaniasis. (C) 2018 Elsevier B.V. All rights reserved.1 aRao, Shilpa, J.1 aShukla, Ekta1 aBhatia, Varsha1 aLohiya, Bharat1 aGaikwad, Sushama, M.1 aKar, Anita1 aPal, Jayanta, K.  uhttps://library.ncl.res.in/content/leishmania-donovani-impact-protein-possesses-non-specific-nuclease-activity