Browsing by Author "Kumar, Rajesh"

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Analysis of the effect of 1-Allyl-3-Methylimidazolium chloride on thermodynamic stability, folding kinetics, and motional dynamics of horse cytochrome c
(Elsevier B.V., 2022-09-08T00:00:00) Garg, Mansi; Sharma, Deepak; Kumar, Rajesh
1-allyl-3-methylimidazolium chloride (AMIMCl) acts as a potential green solvent for proteins. The present work provides a possible pathway by which the structural, kinetic, thermodynamic, and folding properties of horse cytochrome c (cyt c) are affected in green aqueous-AMIMCl systems. Analysis of the effect of AMIMCl on thermodynamic stability, refolding/unfolding kinetics, and motional dynamics of cyt c provided important information, (i) AMIMCl decreases the thermodynamic stability of reduced cyt c and also strengthens the guanidinium chloride (GdmCl)-mediated decrease in thermodynamic stability of protein, (ii) AMIMCl reduces the thermal-fluctuation of Met80-containing omega-loop of natively-folded compact state of carbonmonoxycytochrome c (MCO-state) due to polyfunctional interactions between the AMIM+ and different groups of protein, (iii) AMIMCl shifts the kinetic chevron plot, ln kobs[sbnd][GdmCl] to the lower concentration of GdmCl, (iv) AMIMCl shifts the refolding and unfolding limps to vertically downwards and upwards, respectively, and (v) AMIMCl reducing the unfolding free energy estimated by both thermodynamic and kinetic analysis. � 2022
Analysis of the pH-dependent thermodynamic stability, local motions, and microsecond folding kinetics of carbonmonoxycytochrome c
(Academic Press Inc., 2016) Kumar, Rajesh
This paper analyzes the effect of pH on thermodynamic stability, low-frequency local motions and microsecond folding kinetics of carbonmonoxycytochrome c (Cyt-CO) all across the alkaline pH-unfolding transition of protein. Thermodynamic analysis of urea-induced unfolding transitions of Cyt-CO measured between pH 6 and pH 11.9 reveals that Cyt-CO is maximally stable at pH?9.5. Dilution of unfolded Cyt-CO into refolding medium forms a native-like compact state (NCO-state), where Fe2+?CO interaction persists. Kinetic and thermodynamic parameters measured for slow thermally-driven CO dissociation (NCO?N+CO) and association (N+CO?NCO) reactions between pH 6.5 and pH 13 reveal that the thermal-motions of M80-containing ?-loop are decreased in subdenaturing limit of alkaline pH. Laser photolysis of Fe2+-CO bond in NCO-state triggers the microsecond folding (NCO?N). The microsecond kinetics measured all across the alkaline pH-unfolding transition of Cyt-CO produce rate rollover in the refolding limb of chevron plot, which suggests a glass transition of NCO en route to N. Between pH 7 and pH 11.9, the natural logarithm of the microsecond folding rate varies by?<?1.5 units while the natural logarithm of apparent equilibrium constant varies by 11.8 units. This finding indicates that the pH-dependent ionic-interactions greatly affect the global stability of protein but have very small effect on folding kinetics. ? 2016 Elsevier Inc.
Determinants for macromolecular crowding-induced thermodynamic stabilization of acid-denatured cytochrome c to molten globules
(Elsevier B.V., 2023-07-22T00:00:00) Kumari, Beeta; Shabnam; Yadav, Manisha; Kumar, Manoj; Kushwaha, Pratibha; Prakash Prabhu, N.; Kumar, Rajesh
The macromolecular crowding effect transforms the acid-denatured ferricytochrome c (cyt cIII) (UA-state) to molten-globule (MGMC-state) at pH 1.85. Crowding-induced stabilization free energy (??G) and preferential hydration ??W were estimated for the UA ? MGMC transition. The magnitudes of ??G and ??W were found to be decreased as dextran 70 (D70) > dextran 40 (D40) > ficoll 70 (F70), which demonstrates that ??G and ??W track the molecular size and shape of the crowder towards refolding and stabilization of UA-state to MGMC-state. Analysis of effects of crowders (D40, D70, F70) on thermal and chemical-denaturations of acid-denatured cyt cIII provided several important information, (i) macromolecular crowding increased the thermodynamic stability of acid-denatured cyt cIII, (ii) concentration, size and shape of crowder control the crowding-induced thermodynamic stabilization of MGMC-state, (iii) crowding effect increased the thermal-denaturation midpoint (Tm) with a slight change in enthalpy (?Hm), suggesting that the steric-excluded volume effect contributes to the crowding-induced increased thermal stability of the acid-denatured protein. Analysis of entropy ? enthalpy plots for D40, D70, and F70 reveals that in addition to the steric-excluded volume effect, the enthalpic contribution is also added to the macromolecular crowding-induced stabilization of acid-denatured cyt cIII. The dilute-medium, compound-crowder, purely entropic-crowder and purely enthalpic-crowder curves were obtained for acid-denatured cyt cIII for D70, D40 and F70. The crossover temperature, Tx was calculated from the dilute and compound-crowder curves. The Tx values measured for D40, D70, and F70 were found to be ? 250.15 K, 272.15 K, and 275.15 K, respectively, which suggests that the Tx value depends on the size and shape of the crowder. Furthermore, the observation of a lower value of Tx and a minor enthalpic component for D40, D70, and F70 is likely due to the formation of weaker soft interactions of acid-denatured cyt cIII with D40, D70, and F70. � 2023 Elsevier B.V.
Effect of imidazolium based ionic liquids on CO-association dynamics and thermodynamic stability of Ferrocytochrome c
(Elsevier B.V., 2020-11-05T00:00:00) Garg, Mansi; Kumar, Sandeep; Kaur, Anupamjeet; Goyal, Bhupesh; Kumar, Rajesh
Analysis of kinetic and thermodynamic parameters measured for CO-association reaction of Ferrocytochrome c (Ferrocyt c) under variable concentrations of 1-butyl-3-methylimidazolium with varying anion ([Bmim]X) (X = Cl?, I?, Br?, HSO4?) at pH 7 revealed that the low concentration of [Bmim]X (?0.5 M) constrains the CO-association dynamics of Ferrocyt c and typically follows the order: [Bmim]HSO4 > [Bmim]Cl > [Bmim]Br > [Bmim]I. At relatively higher concentrations (>0.5), the chaotropic action of [Bmim]+ dominates which consequently increases the thermal-fluctuations responsible to denature the protein and thus accelerates the speed of CO-association reaction. Analysis of thermal denaturation curves of Ferrocyt c measured at different concentrations of [Bmim]X revealed that the [Bmim]X decreases the thermodynamic stability of protein and typically follows the order: [Bmim]I > [Bmim]Br > [Bmim]Cl > [Bmim]CH3COO > [Bmim]HSO4, demonstrating that the effect of [Bmim]X on thermodynamic stability of protein is not in accordance to Hofmeister series effect of anions because instead of increasing the kosmotropic anion carrying [Bmim]X ([Bmim]CH3COO and [Bmim]HSO4) also decreases the thermodynamic stability of protein. � 2020 Elsevier B.V.
Factors defining the effects of macromolecular crowding on dynamics and thermodynamic stability of heme proteins in-vitro,
(Elsevier, 2018) Kumar, Rajesh; Sharma, Deepak; Kumar, Vinay; Kumar, Rajesh
The role of crowding agents on structure and activities of heme proteins has been established. Analysis of kinetic and thermodynamic parameters measured for CO-dissociation reaction of natively-folded carbonmonoxycytochrome c (NCO) and carbonmonoxymyoglobin (MbCO) at different [GdnHCl] or [Urea] in the presence of crowding agents (dextran 40, dextran 70 and ficoll 70) demonstrate that (i) at low denaturant concentrations, crowder presence enhances the denaturant-mediated restricted dynamics of NCO and MbCO, and (ii) at higher denaturant concentrations, large scale unfolding-fluctuations dominate the dynamics and inclusion of crowder counteracts the structural-fluctuations causing the unfolding of proteins. Thermodynamic analysis of thermal and urea-unfolding curves of cytochrome c (Cyt c) and myoglobin (Mb) measured at different [GdnHCl] in presence of crowding agents reveals that crowder presence counterbalances and strengthens the destabilizing action of GdnHCl on stability of Cyt c and Mb, respectively. This study further demonstrates that the size, shape and concentration of crowding agent modulate the effect of crowder on denaturant-mediated dynamics and thermodynamic stability of heme proteins.
Factors Defining the Effects of macromolecularcrowding on dynamics and thermodynamics stability of heme proteins in-vitro
(Elsevier, 2018) Kumar, Rajesh; Sharma, Deepak; Kumar, Vinay; Kumar, Rajesh
The role of crowding agents on structure and activities of heme proteins has been established. Analysis of kinetic and thermodynamic parameters measured for CO-dissociation reaction of natively-folded carbonmonoxycytochrome c (NCO) and carbonmonoxymyoglobin (MbCO) at different [GdnHCl] or [Urea] in the presence of crowding agents (dextran 40, dextran 70 and ficoll 70) demonstrate that (i) at low denaturant concentrations, crowder presence enhances the denaturant-mediated restricted dynamics of NCO and MbCO, and (ii) at higher denaturant concentrations, large scale unfolding-fluctuations dominate the dynamics and inclusion of crowder counteracts the structural-fluctuations causing the unfolding of proteins. Thermodynamic analysis of thermal and urea-unfolding curves of cytochrome c (Cyt c) and myoglobin (Mb) measured at different [GdnHCl] in presence of crowding agents reveals that crowder presence counterbalances and strengthens the destabilizing action of GdnHCl on stability of Cyt c and Mb, respectively. This study further demonstrates that the size, shape and concentration of crowding agent modulate the effect of crowder on denaturant-mediated dynamics and thermodynamic stability of heme proteins.
Implication of Methods and Techniques of Relaxation for Investigating the Iron release mechanism of Transferrin
(Central University of Punjab, 2018) Singh, Jitender; Kumar, Rajesh
Transferrins (Tfs, serum transferring (sTf), ovotransferrin (oTf), lactotransferrin(Lf)) are bilobal iron binding glycoprotein's. In the absence of iron, the two lobs are in open conformation. Upon complex formation with iron and the protein is transformed to closed conformation and each lobs forms interdomains hydrogen bond and these are different from one transferrin to other. More over iron release from sTf and oTf take places in mildly acidic media while Lf releases iron in acidic conditions. This difference is likely due to proton assisted di-lysines triggers present in N-lobe of sTF and oTF but absent in Lf. This difference also reflected in kinetic and mechanism of iron release from TFs under mildly acidic pH conditions in the presence of physiological anions. This project discussing the implication of methods and techniques of relaxation for investigating the kinetics and mechanisms of iron release from Tfs' The comparison in kinetic and mechanistic steps of iron release from diferric-sTf, oTf and Lf showed that under mildly acidic conditions, the iron release from diferric-sTf and oTf occur in multiphasic manner while in diferric-sTf it occur it single phase
Include the children who are at risk
(Dr. Ganesh Dass DAV College of Education for Women, 2018) Kumar, Rajesh; Singh, Angrej
Macromolecular crowding on Dynamics and Thermodynamic Stability of Heme Proteins
(Elsevier, 2018) Kumar, Rajesh; Kumar, Rajesh; Sharma, Deepak; Garg, Mansi; Kumar, Vinay; Agarwal, Mukesh Chand
Structural and molecular properties extracted from circular dichroism (CD), tryptophanfluorescence and 1-anilino-8-napthalene sulfonate (ANS) binding experiments suggest that the high concentration of synthetic crowding agents (dextran 40, dextran70 and ficoll 70) stabilizes and refolds the base-denatured ferricytochrome c (Ferricyt c) and lysozyme (Lyz) at pH 12.9 (±0.1) to molten globule (MG) states (CB-states). These results further revealed that the CB-states resemble the generic properties of MG-states. Thermodynamic analysis of thermal denaturation curves of base-denatured Ferricyt c and Lyz at pH 12.9 (±0.1) under variable concentrations of crowding agents (dextran 40, dextran 70 and ficoll 70) revealed that the crowder presence increases the thermal stability of base-denatured proteins and also prevents the cold denaturation of Ferricyt c. The results further showed that the nature, size and shape of crowder influence the crowding-mediated increase in secondary structure stabilization and thermal stability of base-denatured Ferricyt c and Lyz. Analysis of kinetic and thermodynamic parameters measured for CO association reaction of alkaline ferrocytochrome c (Ferrocyt c) at pH 12.9 (±0.1) under variable concentrations of crowding agents (dextran 40, dextran 70 and ficoll 70) revealed that the crowder presence reduces the level of structural fluctuation of M80-containing Ω-loop that control CO association to alkaline Ferrocyt c.
Macromolecular crowding-induced molten globule states of the alkali pH-denatured proteins
(Elsevier B.V., 2018) Kumar, Rajesh; Kumar, Rajesh; Sharma, Deepak; Garg, Mansi; Kumar, Vinay; Agarwal, Mukesh Chand
Structural and molecular properties extracted from circular dichroism (CD), tryptophan fluorescence and 1-anilino-8-napthalene sulfonate (ANS) binding experiments suggest that the high concentration of synthetic crowding agents (dextran 40, dextran 70 and ficoll 70) stabilizes and refolds the base-denatured ferricytochrome c (Ferricyt c) and lysozyme (Lyz) at pH 12.9 (±0.1) to molten globule (MG) states (C B -states). These results further revealed that the C B -states resemble the generic properties of MG-states. Thermodynamic analysis of thermal denaturation curves of base-denatured Ferricyt c and Lyz at pH 12.9 (±0.1) under variable concentrations of crowding agents (dextran 40, dextran 70 and ficoll 70) revealed that the crowder presence increases the thermal stability of base-denatured proteins and also prevents the cold denaturation of Ferricyt c. The results further showed that the nature, size and shape of crowder influence the crowding-mediated increase in secondary structure stabilization and thermal stability of base-denatured Ferricyt c and Lyz. Analysis of kinetic and thermodynamic parameters measured for CO association reaction of alkaline ferrocytochrome c (Ferrocyt c) at pH 12.9 (±0.1) under variable concentrations of crowding agents (dextran 40, dextran 70 and ficoll 70) revealed that the crowder presence reduces the level of structural fluctuation of M80-containing ?-loop that control CO association to alkaline Ferrocyt c. - 2018 Elsevier B.V.
NMR Spectroscopy of Small Sized Proteins
(Central University of Punjab, 2018) Sharma, Vishal; Kumar, Rajesh
In this project, the NMR spectra of proteins is discussed and the one dimensional 1H NMR protein spectra of ferricytochrome and lysozome is collected to study the conformational changes in them by varying the pH values from neutral to alkaline. In this thesis it is focused on that why we are not able to study larger and complex protein molecules with NMR spectra, what are the advantages of NMR spectra in the study of proteins and why we need multidimensions in protein NMR.
Role of Macromolecular Crowding on Stability and Iron Release Kinetics of Serum Transferrin
(American Chemical Society, 2017) Kumar, Sandeep; Sharma, Deepak; Kumar, Rajesh
The macromolecular crowding influences the structural stability and functional properties of transferrin (Tf). The equilibrium as well as kinetic studies of Tf at different concentrations of crowding agents (dextran 40, dextran 70, and ficoll 70) and at a fixed concentration of dextran 40 under different concentrations of NaCl at pH 7.4 and 5.6 (?1) revealed that (i) the crowder environment increases the diferric-Tf (Fe2Tf) stability against iron loss and overall denaturation of the protein, (ii) both in the absence and presence of crowder, the presence of salt promotes the loss of iron and overall denaturation of Fe2Tf which is due to ionic screening of electrostatic interactions, (iii) the crowder environment retards iron release from monoferric N-lobe of Tf (FeNTf) by increasing enthalpic barrier, (iv) the retardation of iron release by crowding is enthalpically dominated than the entropic one, (v) both in the absence and presence of crowder, the presence of salt accelerates the iron release from FeNTf due to ionic screening of electrostatic interactions and anion binding to KISAB sites, and (vi) the crowders environment is unable to diminish (a) the salt-induced destabilization of Fe2Tf against the loss of iron and overall denaturation and (b) the anion effect and ionic screening of diffusive counterions responsible to promote iron release from FeNTf. ? 2017 American Chemical Society.
Single-molecule analysis of osmolyte-mediated nanomechanical unfolding behavior of a protein domain
(Elsevier B.V., 2023-09-16T00:00:00) Bajaj, Manish; Muddassir, Mohd; Choi, Bumjoon; Singh, Priyanka; Park, Jong Bum; Singh, Surjeet; Yadav, Manisha; Kumar, Rajesh; Eom, Kilho; Sharma, Deepak
The small organic molecules, known as osmolytes being ubiquitously present in different cell types, affect protein folding, stability and aggregation. However, it is unknown how the osmolytes affect the nanomechanical unfolding behavior of protein domain. Here, we show the osmolyte-dependent mechanical unfolding properties of protein titin immunoglobulin-27 (I27) domain using an atomic force microscopy (AFM)-based single-molecule force spectroscopy. We found that amines and methylamines improved the mechanical stability of I27 domain, whereas polyols had no effect. Interestingly, glycine betaine (GB) or trimethylamine-N-oxide (TMAO) increased the average unfolding force of the protein domain. The kinetic parameters analyzed at single-molecule level reveal that stabilizing effect of osmolytes is due to a decrease in the unfolding rate constant of I27, which was confirmed by molecular dynamics simulations. Our study reveals different effects that diverse osmolytes have on the mechanical properties of the protein, and suggests the potential use of osmolytes in modulating the mechanical stability of proteins required for various nano-biotechnological applications. � 2023 Elsevier B.V.
Size And Shape Of Crowding Control The Secondary Structure Folding Of Acid- Denatured Cytochrome C
(Central University of Punjab, 2018) Sharma, Manoj; Kumar, Rajesh
Macromolecular crowding, Cytochrome c, Circular Dichroism, Molten Globule, Dextran 40, Dextran 70, Ficoll 70
Structural, kinetic and thermodynamic characterizations of SDS-induced molten globule state of a highly negatively charged cytochrome c
(Oxford University Press, 2019) Jain, R; Sharma, D; Kumar, Rakesh; Kumar, Rajesh
This study presents the structural, kinetic and thermodynamic characterizations of previously unknown submicellar concentrations of SDS-induced molten globule (MGSDS) state of a highly negatively charged basedenatured ferricytochrome c (U B -state) at pH ∼12.8 (±0.2). The far-UV CD, near-UV CD, ANS-fluorescence data of UB-state in the presence of different concentrations of SDS indicate that the submicellar concentrations of SDS (≤0.4mM) transform the UBstate to MG SDS -state. The MG SDS -state has nativelike α-helical secondary structure but lacks tertiary structure. The free energy change (ΔG° D) for U B → MG SDS transition determined by far-UV CD (∼2.7 kcal mol -1 ) is slightly higher than those determined by fluorescence (∼2.0 kcal mol -1 ) at 25°C. At very low SDS and NaCl concentrations, the MG SDS -state undergoes cold denaturation. As SDS concentration is increased, the thermal denaturation temperature increases and the cold denaturation temperature decrease. Kinetic experiments involving the measurement of the CO-association rate to the base-denatured ferrocytochrome c at pH ≈12.8 (±0.2), 25°C indicate that the submicellar concentrations of SDS restrict the internal dynamics of base-denatured protein. © The Author(s) 2018. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.
Substitution of carbonate by non-physiological synergistic anion modulates the stability and iron release kinetics of serum transferrin
(Elsevier B.V., 2022-10-15T00:00:00) Kumar, Rajesh; Sharma, Deepak; Kumar, Navinder; Kumari, Beeta; Shabnam; Kumar, Sanjeev
Serum transferrin (sTf) is a bi-lobal protein. Each lobe of sTf binds one Fe3+ ion in the presence of a synergistic anion. Physiologically, carbonate is the main synergistic anion but other anions such as oxalate, malonate, glycolate, maleate, glycine, etc. can substitute for carbonate in vitro. The present work provides the possible pathways by which the substitution of carbonate with oxalate affects the structural, kinetic, thermodynamic, and functional properties of blood plasma sTf. Analysis of equilibrium experiments measuring iron release and structural unfolding of carbonate and oxalate bound diferric-sTf (Fe2sTf) as a function of pH, urea concentration, and temperature reveal that the structural and iron-centers stability of Fe2sTf increase by substitution of carbonate with oxalate. Analysis of isothermal titration calorimetry (ITC) scans showed that the affinity of Fe3+ with apo-sTf is enhanced by substituting carbonate with oxalate. Analysis of kinetic and thermodynamic parameters measured for the iron release from the carbonate and oxalate bound monoferric-N-lobe of sTf (FeNsTf) and Fe2sTf at pH 7.4 and pH 5.6 reveals that the substitution of carbonate with oxalate inhibits/retards the iron release via increasing the enthalpic barriers. � 2022 Elsevier B.V.
Tah1, A Key Component of R2TP Complex that Regulates Assembly of snoRNP, is Involved in De Novo Generation and Maintenance of Yeast Prion [URE3]
(Academic Press, 2021-03-31T00:00:00) Puri, Anuradhika; Singh, Priyanka; Kumar, Navinder; Kumar, Rajesh; Sharma, Deepak
The cellular chaperone machinery plays key role in the de novo formation and propagation of yeast prions (infectious protein). Though the role of Hsp70s in the prion maintenance is well studied, how Hsp90 chaperone machinery affects yeast prions remains unclear. In the current study, we examined the role of Hsp90 and its co-chaperones on yeast prions [PSI+] and [URE3]. We show that the overproduction of Hsp90 co-chaperone Tah1, cures [URE3] which is a prion form of native protein Ure2 in yeast. The Hsp90 co-chaperone Tah1 is involved in the assembly of small nucleolar ribonucleoproteins (snoRNP) and chromatin remodelling complexes. We found that Tah1 deletion improves the frequency of de novo appearance of [URE3]. The Tah1 was found to interact with Hsp70. The lack of Tah1 not only represses antagonizing effect of Ssa1 Hsp70 on [URE3] but also improves the prion strength suggesting role of Tah1 in both fibril growth and replication. We show that the N-terminal tetratricopeptide repeat domain of Tah1 is indispensable for [URE3] curing. Tah1 interacts with Ure2, improves its solubility in [URE3] strains, and affects the kinetics of Ure2 fibrillation in vitro. Its inhibitory role on Ure2 fibrillation is proposed to influence [URE3] propagation. The present study shows a novel role of Tah1 in yeast prion propagation, and that Hsp90 not only promotes its role in ribosomal RNA processing but also in the prion maintenance. Prions are self-perpetuating infectious proteins. What initiates the misfolding of a protein into its prion form is still not clear. The understanding of cellular factors that facilitate or antagonize prions is crucial to gain insight into the mechanism of prion formation and propagation. In the current study, we reveal that Tah1 is a novel modulator of yeast prion [URE3]. The Hsp90 co-chaperone Tah1, is required for the formation of small nucleolar ribonucleoprotein complex. We show that the absence of Tah1 improves the induction of [URE3] prion. The overexpressed Tah1 cures [URE3], and this function is promoted by Hsp90 chaperones. The current study thus provides a novel cellular factor and the underlying mechanism, involved in the prion formation and propagation � 2021 Elsevier Ltd
Tah1, A Key Component of R2TP Complex that Regulates Assembly of snoRNP, is Involved in De Novo Generation and Maintenance of Yeast Prion [URE3]
(Academic Press, 2021-03-31T00:00:00) Puri, Anuradhika; Singh, Priyanka; Kumar, Navinder; Kumar, Rajesh; Sharma, Deepak
The cellular chaperone machinery plays key role in the de novo formation and propagation of yeast prions (infectious protein). Though the role of Hsp70s in the prion maintenance is well studied, how Hsp90 chaperone machinery affects yeast prions remains unclear. In the current study, we examined the role of Hsp90 and its co-chaperones on yeast prions [PSI+] and [URE3]. We show that the overproduction of Hsp90 co-chaperone Tah1, cures [URE3] which is a prion form of native protein Ure2 in yeast. The Hsp90 co-chaperone Tah1 is involved in the assembly of small nucleolar ribonucleoproteins (snoRNP) and chromatin remodelling complexes. We found that Tah1 deletion improves the frequency of de novo appearance of [URE3]. The Tah1 was found to interact with Hsp70. The lack of Tah1 not only represses antagonizing effect of Ssa1 Hsp70 on [URE3] but also improves the prion strength suggesting role of Tah1 in both fibril growth and replication. We show that the N-terminal tetratricopeptide repeat domain of Tah1 is indispensable for [URE3] curing. Tah1 interacts with Ure2, improves its solubility in [URE3] strains, and affects the kinetics of Ure2 fibrillation in vitro. Its inhibitory role on Ure2 fibrillation is proposed to influence [URE3] propagation. The present study shows a novel role of Tah1 in yeast prion propagation, and that Hsp90 not only promotes its role in ribosomal RNA processing but also in the prion maintenance. Prions are self-perpetuating infectious proteins. What initiates the misfolding of a protein into its prion form is still not clear. The understanding of cellular factors that facilitate or antagonize prions is crucial to gain insight into the mechanism of prion formation and propagation. In the current study, we reveal that Tah1 is a novel modulator of yeast prion [URE3]. The Hsp90 co-chaperone Tah1, is required for the formation of small nucleolar ribonucleoprotein complex. We show that the absence of Tah1 improves the induction of [URE3] prion. The overexpressed Tah1 cures [URE3], and this function is promoted by Hsp90 chaperones. The current study thus provides a novel cellular factor and the underlying mechanism, involved in the prion formation and propagation � 2021 Elsevier Ltd