01994nas a2200169   4500008004100000022001400041245014800055210006900203260000900272300001400281490000800295520133600303100002201639700002001661700001501681856012801696       2024                        eng d  a1520-610600aCharacterization of the conformational hotspots of the RNA-dependent RNA polymerase complex identifies a unique structural malleability of nsp80 aCharacterization of the conformational hotspots of the RNAdepend  cOCT   a9959-99750 v1283 a<p>
	Several antiviral therapeutic approaches have been targeted toward the RNA-dependent RNA polymerase (RdRp) complex that is involved in viral genome replication. In SARS-CoV-2, although the RdRp is a multiprotein complex, the focus has been on the ligand binding catalytic core (nonstructural protein nsp12), and not the multiprotein functional dynamics. In this study, we focus on the conformational ensembles of the RdRp complex and their modulation by the presence of RNA, performing comprehensive microsecond-scale atomistic simulations of the apo- and RNA-bound complex. We delineate the differential impact of RNA on the constituent proteins, such as conformational polymorphisms, dominant segment-specific fluctuations, and the switch in dynamical crosstalk within the complex. We distinguish dynamical signatures of nsp7, nsp8, and nsp12 in the apo-state that are reduced in the presence of the RNA and appear to ``prime'' the complex for activity. Importantly, we identify a unique structural malleability of the nsp8 protein with high conformational heterogeneity in the apo state, especially at three sites (Y71 for nsp8A, and D52 and A66 for nsp8B). Our work highlights the functional implications of the polymorphism of nsp8 structures and reveals possibilities for the development of allosteric inhibitors.</p>
1 aGharui, Sowmomita1 aSengupta, Durba1 aDas, Atanu  uhttps://library.ncl.res.in/content/characterization-conformational-hotspots-rna-dependent-rna-polymerase-complex-identifies02205nas a2200241   4500008004100000022001400041245009500055210006900150260000800219300001200227490000700239520141000246653002001656653002301676653001201699653002201711100002301733700002301756700002301779700001501802700002501817856012101842       2025                        eng d  a1572-388700aCharacterization of S-homocysteinylation of Human Insulin and Its Implications in Diabetes0 aCharacterization of Shomocysteinylation of Human Insulin and Its  cOCT  a598-6100 v443 a<p>
	Homocysteine thiolactone is a reactive thiol known for its interaction with various proteins. Nevertheless, there exists a paucity of information concerning the interaction between homocysteine thiolactone and human insulin, particularly regarding the mechanism by which homocysteine facilitates the reduction of disulfide bonds within insulin. In the present study, we have elucidated the binding sites of homocysteine to the cysteine residues (A6-B7 and A20-B19) that are implicated in the formation of intermolecular disulfide bonds in insulin through an in vitro reaction analyzed via LC-ESI MS/MS. This results in a reduction of disulfide bonds linking the A and B chains, which was corroborated by MALDI-TOF-MS and ESI-MS analysis. The secondary structure of insulin is affected by this modification, as evidenced by circular dichroism spectroscopy. In-silico studies also show that homocysteine affects the insulin structure. A glucose uptake assay conducted in Chinese hamster ovary (CHO) cells that stably express the insulin receptor revealed that HC-modified insulin is less effective in inducing glucose uptake compared to native insulin, suggesting that HC-induced structural modifications in insulin influence functional activity. This study provides insight into the HC-induced structural and functional changes in insulin and discusses the consequent implications for diabetes.</p>
10aDisulfide bonds10aHomocysteinylation10ainsulin10aMass spectrometry1 aSheikh, Amreen, B.1 aJathar, Swaraj, M.1 aTammara, Vaishnavi1 aDas, Atanu1 aKulkarni, Mahesh, J.  uhttps://library.ncl.res.in/content/characterization-s-homocysteinylation-human-insulin-and-its-implications-diabetes