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Ray S, Singh N, Patel K, Krishnamoorthy G, Maji SK. FRAP and FRET Investigation of α-Synuclein Fibrillization via Liquid-Liquid Phase Separation In Vitro and in HeLa Cells. Methods Mol Biol 2023; 2551:395-423. [PMID: 36310217 DOI: 10.1007/978-1-0716-2597-2_26] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Liquid-liquid phase separation (LLPS) acts as an important biological phenomenon in membraneless organelle formation. These phase-separated bodies can also act as nucleation centers for disease-associated amyloid formation. Fluorescence recovery after photobleaching (FRAP) is a crucial technique to analyze the material property (liquid or solid) of protein LLPS. On the other hand, Förster resonance energy transfer (FRET) is used to understand the domain-specific involvement (intermolecular interactions) of protein molecules inside the phase-separated droplets. In this protocol, we delineate mechanisms of liquid-to-solid transition of α-synuclein LLPS by using in vitro and in cell FRAP as well as in vitro FRET techniques.
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Affiliation(s)
- Soumik Ray
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Nitu Singh
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Komal Patel
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | | | - Samir K Maji
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India.
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2
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Das M, Brahma M, Krishnamoorthy G. Host-guest interaction aided Zinc carry and delivery by ESIPT active 2-(2'-hydroxyphenyl)benzoxazole. Spectrochim Acta A Mol Biomol Spectrosc 2022; 281:121474. [PMID: 35797954 DOI: 10.1016/j.saa.2022.121474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 05/30/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
The effect of solvents and supramolecular hosts on the binding of metal ion with an excited state intramolecular proton transfer (ESIPT) active fluorophore 2-(2'-hydroxyphenyl)benzoxazole (HPBO) are investigated to scrutinize a possible metal ion carry and delivery system. The fluorophore forms strong fluorescent complex with Zn2+ ion. In aqueous medium, β-cyclodextrin (β-CD) breaks the HPBO-Zn2+ complex and encapsulate the freed fluorophore. Hence, the initially blocked ESIPT process is restored by forming an inclusion complex with the host molecules. However, in dimethyl sulphoxide (DMSO), β-CD does not break the complex. But cucurbit[7]uril (CB-7) breaks the complex in both DMSO and water. The tuned emission characteristics are considered for constructing different molecular logic gates. BUFFER, NOT, PASS, IMPLICATION and INHIBIT logic operations are substantiated based on Zn2+, CB-7 and β-CD response.
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Affiliation(s)
- Minati Das
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Mongoli Brahma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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3
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Brahma M, Ranjan S, Tripathi P, Krishnamoorthy G. Modifying the proton transfer of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole by water, confinement and confined water. Spectrochim Acta A Mol Biomol Spectrosc 2022; 272:120911. [PMID: 35131618 DOI: 10.1016/j.saa.2022.120911] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/04/2022] [Accepted: 01/15/2022] [Indexed: 06/14/2023]
Abstract
The effect of water, confinement and confined water on the proton transfer of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole (bis-HPTA) was investigated. Water alters the proton transfer process. At higher pH, an anion is formed in water and it undergoes intermolecular proton transfer and forms a keto tautomer. Confinement of molecule in β-cyclodextrin affects the intramolecular proton transfer. It also prevents the intermolecular proton transfer of the anionic form. In reverse micelle, the molecule resides in the interfacial region and interacts with bound water. The intermolecular hydrogen bond of the surfactants opens the intramolecular hydrogen bond in the weaker β-ring of bis-HPTA. It led to single tautomer emission from bis-HPTA. An increase in water amount enhances the relative amount of trans-enol, but predominantly tautomer emission is observed.
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Affiliation(s)
- Mongoli Brahma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Sanjeev Ranjan
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Pravesh Tripathi
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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4
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Das M, Brahma M, Shimray SA, Chipem FAS, Krishnamoorthy G. Nanoparticle and surfactant controlled switching between proton transfer and charge transfer reaction coordinates. Phys Chem Chem Phys 2022; 24:4944-4956. [PMID: 35138315 DOI: 10.1039/d1cp02165f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction coordinates of a molecular photo-switch 2-(4'-diethylamino-2'-hydroxyphenyl)-1H-imidazo-[4,5-b]pyridine (DHP) was tuned with a nanoparticle and surfactant. DHP undergoes excited state intramolecular proton transfer (ESIPT) and emits normal and tautomer emissions in N,N-dimethylformamide. Silver nanoparticles suppress the ESIPT and induce twisted intramolecular charge transfer (TICT). Further addition of surfactants alters the process. Interestingly, different surfactants cause different effects. Accordingly, the luminescence characteristics are altered. The anionic surfactant sodium dodecyl sulfate (SDS) restores the ESIPT process by completely detaching the molecule from the nanoparticle. The nonionic surfactant Triton X-100 (TX-100), at lower concentration, enhances the TICT emission and the ESIPT process is also observed due to the release of some fluorophore from the nanoparticle complex. But at higher concentration the fluorophores are released completely and the ESIPT process is restored. The cationic surfactant cetyltrimethyl ammonium bromide (CTAB), at lower concentration, simply restores the ESIPT process by releasing the fluorophore. But at higher CTAB concentration, DHP enters the metalparticle-CTAB aggregate and shows enhanced ESIPT.
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Affiliation(s)
- Minati Das
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
| | - Mongoli Brahma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
| | - Sophy A Shimray
- Department of Chemistry, Manipur University, Imphal, Manipur 795003, India
| | - Francis A S Chipem
- Department of Chemistry, Manipur University, Imphal, Manipur 795003, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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5
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Patra C, Suganya E, Sivaprakasam S, Krishnamoorthy G, Narayanasamy S. A detailed insight on fabricated porous chitosan in eliminating synthetic anionic dyes from single and multi-adsorptive systems with related studies. Chemosphere 2021; 281:130706. [PMID: 34020190 DOI: 10.1016/j.chemosphere.2021.130706] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Chitosan was fabricated via gelation method using CaBr2.xH2O/methanol solution and was studied as a potential adsorbent (MCh) in adsorbing anionic synthetic dyes like Bromophenol blue (BB), Direct blue 6 (DB) and Congo red (CR) from single (one dye species at a time) and multi (having two dyes; binary and all three dyes; tertiary) adsorptive systems. Physico-chemical modifications of MCh surface prior and post modification and dye adsorption were evaluated using scanning electron microscopy, Energy-dispersive X-ray spectroscopy, powder X-ray diffraction analysis, surface area analysis and Fourier-transformed infrared spectroscopy. Influential parameters influencing the adsorption process viz. initial pH of dye solution, MCh dosage, adsorption temperature and initial concentration of dye species were optimised. Adsorptive studies involving single adsorptive setups verified formation of sorbate's (dye species) monolayer over the sorbent's (MCh) surface via chemisorption; as established by Langmuir isotherm and pseudo-second order kinetics model analysis. Theoretical maximum adsorption capacities of MCh for BB, DB and CR was found to be 81.301 mg/g, 163.934 mg/g and 75.758 mg/g, respectively. Meanwhile, for all multi-adsorptive systems, competitive Langmuir isotherm model verified antagonistic behaviour of an individual dye over other dye adsorption over MCh surface in their respective adsorptive systems. Thermodynamics of the sorbate-sorbent interaction was exothermic, spontaneous, with elevated degree of disorderedness; concluding the interaction as thermodynamically favourable. Co-existing metal cations and anionic salts had minimal effect on MCh's adsorption efficiency. Phytotoxicity assay via germination of Vigna mungo seeds verified the efficacy of the adsorbent in eliminating the dye species from single and multi-adsorptive systems.
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Affiliation(s)
- Chandi Patra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - E Suganya
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Senthilkumar Sivaprakasam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Selvaraju Narayanasamy
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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Abstract
A molecular photoswitch, 2-(4'-diethylamino-2'-hydroxyphenyl)-1H-imidazo-[4,5-b]pyridine (DHP), with mutually independent paths of excited-state intramolecular proton transfer (ESIPT) and twisted intramolecular charge transfer (TICT) was developed. Control over these processes was attained by switching the solvents. Depending on the solvent's hydrogen-bond capacity and polarity, either one of the photoprocesses (ESIPT or TICT) or both can be triggered. Accordingly, normal and tautomer emissions, normal and TICT emissions, or triple emission of normal, tautomer, and TICT were obtained from the molecule. The emissions were resolved by fluorescence lifetime. The conclusions were established by synthesizing and studying the methoxy derivative of the molecule.
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Affiliation(s)
- Minati Das
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Mongoli Brahma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
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Krishnamoorthy G, Arsene C, Jena N, Mogulla SM, Coakley R, Khine J, Khosrodad N, Klein A, Sule AA. Racial disparities in COVID-19 hospitalizations do not lead to disparities in outcomes. Public Health 2021; 190:93-98. [PMID: 33385640 PMCID: PMC7698674 DOI: 10.1016/j.puhe.2020.11.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/09/2020] [Accepted: 11/22/2020] [Indexed: 02/08/2023]
Abstract
OBJECTIVES The objective of the study is the identification of racial differences in characteristics and comorbidities in patients hospitalized for COVID-19 and the impact on outcomes. STUDY DESIGN The study design is a retrospective observational study. METHODS Data for all patients admitted to seven community hospitals in Michigan, United States, with polymerase chain reaction confirmed diagnosis of COVID-19 from March 10 to April 15, 2020 were analyzed. The primary outcomes of racial disparity in inpatient mortality and intubation were analyzed using descriptive statistics and multivariate regression models. RESULTS The study included 336 Black and 408 White patients. Black patients were younger (62.9 ± 15.0 years vs 71.8 ± 16.4, P < .001), had a higher mean body mass index (32.4 ± 8.6 kg/m2 vs 28.8 ± 7.5, P < .001), had higher prevalence of diabetes (136/336 vs 130/408, P = .02), and presented later (6.6 ± 5.3 days after symptom onset vs. 5.4 ± 5.4, P = .006) compared with White patients. Younger Black patients had a higher prevalence of obesity (age <65 years, 69.9%) than older Black patients (age >65 years, 39.2%) and younger White patients (age < 65, 55.1%). Intubation did not reach statistical significance for racial difference (Black patients 61/335 vs. 54/406, P = .08). Mortality was not higher in Black patients (65/335 vs. 142/406 in White patients, odds ratio 0.61, 95% confidence interval: 0.37 to 0.99, 2-sided P = .05) in multivariate analysis, accounting for other risk factors associated with mortality. CONCLUSIONS Higher prevalence of obesity and diabetes in young Black populations may be the critical factor driving disproportionate COVID-19 hospitalizations in Black populations. Hospitalized Black patients do not have worse outcomes compared with White patients.
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Affiliation(s)
| | - C Arsene
- ProMedica Health System, Toledo, OH, United States
| | - N Jena
- St Joseph Mercy Oakland Hospital, Pontiac, MI, United States
| | - S M Mogulla
- St Joseph Mercy Oakland Hospital, Pontiac, MI, United States
| | - R Coakley
- Ross University School of Medicine, United States
| | - J Khine
- St Joseph Mercy Oakland Hospital, Pontiac, MI, United States
| | - N Khosrodad
- St Joseph Mercy Oakland Hospital, Pontiac, MI, United States
| | - A Klein
- Ross University School of Medicine, United States
| | - A A Sule
- St Joseph Mercy Oakland Hospital, Pontiac, MI, United States.
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8
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Kumar MS, Krishnamoorthy G, Vaithiyanathan D. Synchrosqueezing Transform Based Powerline Interference Reduction in ECG Recording. j med imaging hlth inform 2020. [DOI: 10.1166/jmihi.2020.3174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This paper presents an adaptive ECG enhancement procedure based on Synchrosqueezing Transform (SST) to eliminate Powerline interference (PLI) from ECG signal. This work also incorporates the principles of modified discrete cosine transform (MDCT) and wiener filter. PLI is a major source
of artifacts in the ECG signal which can affect its interpretation. Separating PLI from ECG signal poses a great challenge in the ECG analysis. The existing PLI removal techniques suffer from two major drawbacks such as Mode Mixing, inability to deal with non-stationary characteristics of
signal. In this paper, we propose SST based wiener filtering approaches which can overcome the limitation of existing PLI suppression techniques. The proposed approaches undergo three stages of operation: mode decomposition, mode determination and peak restoration to filter out PLI from ECG
recording. The mode decomposition uses SST to decompose the corrupted ECG signal into a sum of well separated intrinsic mode functions (IMFs). The objective is to filter out PLI from these IMFs. To do so, mode determination step which is based on Kurtosis and Crest factor is applied to categorize
decomposition result into groups such as signal mode and noisy mode. Direct subtraction of the noisy mode from the corrupted ECG observation results in ECG signal with reduced peak since noise mode carries part of signal components in addition to interference. Hence, to restore the peak, wiener
filter is applied on noisy mode to estimate actual PLI component. Finally, Noise free ECG signal is reconstructed by subtracting estimated PLI from the corrupted ECG signal. This paper discusses four possible PLI suppression methods which are derived by combining SST domain with wiener filter
in various ways. Simulations are carried out to test the effectiveness of proposed methods. It is evident from the simulation results that the proposed methods can remove PLI of 50 Hz and its harmonics. The proposed techniques effectively removed PLI in both real and artificial ECG signals
and to test its performance they are compared with state of the art methods. The SST based filtering methods outperformed other methods under the condition of PLI frequency variations. The experimental results also suggest that the SST based wiener filtering with modified reference approach
offers better PLI suppression than all other methods.
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9
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Shrivastava S, Paila YD, Kombrabail M, Krishnamoorthy G, Chattopadhyay A. Role of Cholesterol and Its Immediate Biosynthetic Precursors in Membrane Dynamics and Heterogeneity: Implications for Health and Disease. J Phys Chem B 2020; 124:6312-6320. [DOI: 10.1021/acs.jpcb.0c04338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sandeep Shrivastava
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Yamuna Devi Paila
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Mamata Kombrabail
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
| | - G. Krishnamoorthy
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
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Ray S, Singh N, Kumar R, Patel K, Pandey S, Datta D, Mahato J, Panigrahi R, Navalkar A, Mehra S, Gadhe L, Chatterjee D, Sawner AS, Maiti S, Bhatia S, Gerez JA, Chowdhury A, Kumar A, Padinhateeri R, Riek R, Krishnamoorthy G, Maji SK. α-Synuclein aggregation nucleates through liquid-liquid phase separation. Nat Chem 2020; 12:705-716. [PMID: 32514159 DOI: 10.1038/s41557-020-0465-9] [Citation(s) in RCA: 333] [Impact Index Per Article: 83.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 04/07/2020] [Indexed: 12/22/2022]
Abstract
α-Synuclein (α-Syn) aggregation and amyloid formation is directly linked with Parkinson's disease pathogenesis. However, the early events involved in this process remain unclear. Here, using the in vitro reconstitution and cellular model, we show that liquid-liquid phase separation of α-Syn precedes its aggregation. In particular, in vitro generated α-Syn liquid-like droplets eventually undergo a liquid-to-solid transition and form an amyloid hydrogel that contains oligomers and fibrillar species. Factors known to aggravate α-Syn aggregation, such as low pH, phosphomimetic substitution and familial Parkinson's disease mutations, also promote α-Syn liquid-liquid phase separation and its subsequent maturation. We further demonstrate α-Syn liquid-droplet formation in cells. These cellular α-Syn droplets eventually transform into perinuclear aggresomes, the process regulated by microtubules. This work provides detailed insights into the phase-separation behaviour of natively unstructured α-Syn and its conversion to a disease-associated aggregated state, which is highly relevant in Parkinson's disease pathogenesis.
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Affiliation(s)
- Soumik Ray
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Nitu Singh
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Rakesh Kumar
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Komal Patel
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | | | - Debalina Datta
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | | | | | - Ambuja Navalkar
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Surabhi Mehra
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Laxmikant Gadhe
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | | | - Ajay Singh Sawner
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Siddhartha Maiti
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | - Sandhya Bhatia
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Juan Atilio Gerez
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zürich, Switzerland
| | | | - Ashutosh Kumar
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India
| | | | - Roland Riek
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zürich, Switzerland
| | | | - Samir K Maji
- Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India.
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Abstract
The development of new antibiotics against Gram-negative bacteria is hampered by the powerful protective properties of their cell envelope. This envelope consists of two membranes augmented by efflux transporters, which act in synergy to restrict cellular access to a broad range of chemical compounds. Recently, a kinetic model of this system has been constructed. The model revealed a complex, nonlinear behavior of the system, complete with a bifurcation, and matched very well to experimental uptake data. Here, we expand the model to include multiple transporters and apply it to an experimental analysis of antibiotic accumulation in wild-type and efflux-deficient Escherichia coli. We show that transporters acting across the inner and outer membranes have synergistic effects with each other. In contrast, transporters acting across the same membrane are additive as a rule but can be synergistic under special circumstances owing to a bifurcation controlled by the barrier constant. With respect to ethidium bromide, the inner membrane transporter MdfA was synergistic to the TolC-dependent efflux across the outer membrane. The agreement between the model and drug accumulation was very good across a range of tested drug concentrations and strains. However, antibiotic susceptibilities related only qualitatively to the accumulation of the drugs or predictions of the model and could be fit to the model only if additional assumptions were made about the physiological consequences of prolonged cell exposure to the drugs. Thus, the constructed model correctly predicts transmembrane permeation of various compounds and potentially their intracellular activity.
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Affiliation(s)
- Paramita Saha
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Samapan Sikdar
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Ganesh Krishnamoorthy
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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12
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Ila, Dani R, Verma SP, Krishnamoorthy G. The origin of the longer wavelength emission in 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole and its analogue 2-phenylamino-5-(2-hydroxybenzono)-1,3,4-thiadiazole. Photochem Photobiol Sci 2020; 19:844-853. [DOI: 10.1039/c9pp00490d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/26/2020] [Indexed: 11/21/2022]
Abstract
The longer wavelength emissions of 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT) and 2-phenylamino-5-(2-hydroxybenzono)-1,3,4-thiadiazole (PHBT) are due to ESIPT.
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Affiliation(s)
- Ila
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Reshmi Dani
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Surya Pratap Verma
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
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13
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Mukhopadhyay A, Mehra S, Kumar R, Maji SK, Krishnamoorthy G, Sharma KP. α-Synuclein Spontaneously Adopts Stable and Reversible α-Helical Structure in Water-Less Environment. Chemphyschem 2019; 20:2783-2790. [PMID: 31515915 DOI: 10.1002/cphc.201900868] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/12/2019] [Indexed: 11/07/2022]
Abstract
A highly stable, spontaneous, and reversible α-helical-structure formation in recombinant and chemically modified α-synuclein protein is demonstrated for the first time in a water-less (1.5 % w/w H2 O) polymer surfactant environment. Using a combination of circular dichroism and ATR-FTIR spectroscopy, we show that whilst native α-synuclein in aqueous solution shows a predominant unordered conformation (≈64 %), mixing with polyethylene glycol based anionic polymer surfactant (PS) and removing water reveals a 25 % unordered, 25 % α-helical, and 27 % β-sheet structure. Interestingly, bioconjugation of native α-synuclein with a diamine molecule, to increase the positive charge on the protein chain, and subsequent electrostatic coupling with the PS forms a conjugate with a retained unordered structure. Removal of water from this system provides a highly stable α-helical (≈74 %) water-less liquid system. Surprisingly, the α-helical-to-unordered state transition is completely reversible and is achieved at ≈25-30 w/w% of water in the system. Moreover, the α-helix shows an extraordinary temporal stability (>6 months) in a waterless environment.
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Affiliation(s)
- Anasua Mukhopadhyay
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-, 400076, INDIA
| | - Surabhi Mehra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai-, 400076, INDIA
| | - Raj Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-, 400076, INDIA
| | - Samir K Maji
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai-, 400076, INDIA
| | - G Krishnamoorthy
- Department of Biotechnology, Anna University, Chennai-, 600025, INDIA
| | - Kamendra P Sharma
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-, 400076, INDIA
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14
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Mariam J, Krishnamoorthy G, Anand R. Use of 6‐Methylisoxanthopterin, a Fluorescent Guanine Analog, to Probe Fob1‐Mediated Dynamics at the Stalling Fork Barrier DNA Sequences. Chem Asian J 2019; 14:4760-4766. [DOI: 10.1002/asia.201901061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 09/19/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Jessy Mariam
- Department of ChemistryIndian Institute of Technology Bombay Powai Mumbai 400076 Maharashtra India
| | | | - Ruchi Anand
- Department of ChemistryIndian Institute of Technology Bombay Powai Mumbai 400076 Maharashtra India
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15
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Das M, Sahu S, Krishnamoorthy G. Tweaking the proton transfer triggered proton transfer of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole. Phys Chem Chem Phys 2019; 21:15669-15677. [DOI: 10.1039/c9cp02281c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Proton transfer triggered proton transfer (PTTPT) of the molecule is completely altered by dimethylformamide and the proton transfer paths are changed. The process can be reversed by silver particle.
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Affiliation(s)
- Minati Das
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - Saugata Sahu
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
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16
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Krishnamoorthy G, Kannan S, Marudhamuthu M. Bioactive compound from Aspergillus terreusDMTMGK004 synergistically contributes towards potential anti-pathogenicity. Lett Appl Microbiol 2018; 67:579-588. [PMID: 30203855 DOI: 10.1111/lam.13071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/29/2018] [Accepted: 09/01/2018] [Indexed: 12/29/2022]
Abstract
This study focused on the evaluation of fungal compound for their anti-pathogenic potential against respiratory pathogens. Soil samples were collected from various geographical regions in Madurai, fungal strain was isolated and identified as Aspergillus terreusDMTMGK004 (MGK004). Secondary metabolites were extracted and evaluated for antioxidant potential. It exhibited significantly high anti-proliferative property against gastric adenocarcinoma (AGS) cell lines. Antimicrobial activity against Gram positive (Streptococcus pneumoniae) and Gram negative (Klebsiella pneumoniae and Haemophilus influenzae) respiratory pathogens were analysed and the minimum inhibitory concentration (MIC) values were determined. Furthermore, the time-killing assay illustrated that the metabolite eliminates 50% of the vegetative cells within few hours of the treatment. From the spectral data, the major functional groups present in the compound were determined as carbonyl group and phenolic hydroxyl group which contribute towards its bioactivity. The compound significantly depreciates the production of extracellular polysaccharides which results in the weakening of biofilm architecture and resistance towards serum killing and phagocytosis. It also induced cell membrane damage which leads to protein and nucleic acid leakage. Hence, the results of the present study could provide a better insinuation towards the formulation of new drug targeting respiratory pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: The ubiquitous fungi Aspergillus terreus is well known for its secondary metabolite production. The fungus was evaluated for production of antagonistic molecule to reduce the growth of infectious agents causing respiratory infections. It exhibited the biological means of antioxidant, anti-proliferative and anti-pathogenic compound production. The compound exhibits killing effect against respiratory pathogens within two hours. It induced cell membrane damage leading to protein and nucleic acid leakage. It significantly reduced the production of extracellular polysaccharides. The results provide needed information to design innovative strategies for targeting pathogenic factors of the respiratory pathogens instead of killing it precisely.
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Affiliation(s)
- G Krishnamoorthy
- Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, India
| | - S Kannan
- Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, India
| | - M Marudhamuthu
- Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, India
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17
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Krishnamoorthy G. Intramolecular Distance Distribution Reveals Mechanisms in Protein Folding and Dynamics. Proc Natl Acad Sci , India, Sect A Phys Sci 2018. [DOI: 10.1007/s40010-018-0525-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Cooper CJ, Krishnamoorthy G, Wolloscheck D, Walker JK, Rybenkov VV, Parks JM, Zgurskaya HI. Molecular Properties That Define the Activities of Antibiotics in Escherichia coli and Pseudomonas aeruginosa. ACS Infect Dis 2018; 4:1223-1234. [PMID: 29756762 DOI: 10.1021/acsinfecdis.8b00036] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The permeability barrier of Gram-negative cell envelopes is the major obstacle in the discovery and development of new antibiotics. In Gram-negative bacteria, these difficulties are exacerbated by the synergistic interaction between two biochemically distinct phenomena, the low permeability of the outer membrane (OM) and active multidrug efflux. In this study, we used Pseudomonas aeruginosa and Escherichia coli strains with controllable permeability barriers, achieved through hyperporination of the OMs and varied efflux capacities, to evaluate the contributions of each of the barriers to protection from antibacterials. We analyzed antibacterial activities of β-lactams and fluoroquinolones, antibiotics that are optimized for targets in the periplasm and the cytoplasm, respectively, and performed a machine learning-based analysis to identify physicochemical descriptors that best classify their relative potencies. Our results show that the molecular properties selected by active efflux and the OM barriers are different for the two species. Antibiotic activity in P. aeruginosa was better classified by electrostatic and surface area properties, whereas topology, physical properties, and atom or bond counts best capture the behavior in E. coli. In several cases, descriptor values that correspond to active antibiotics also correspond to significant barrier effects, highlighting the synergy between the two barriers where optimizing for one barrier promotes strengthening of the other barrier. Thus, both barriers should be considered when optimizing antibiotics for favorable OM permeability, efflux evasion, or both.
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Affiliation(s)
- Connor J. Cooper
- Graduate School of Genome Science and Technology, University of Tennessee, F225 Walters Life Science, Knoxville, Tennessee 37996, United States
| | - Ganesh Krishnamoorthy
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - David Wolloscheck
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - John K. Walker
- Department of Pharmacological & Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Jerry M. Parks
- Graduate School of Genome Science and Technology, University of Tennessee, F225 Walters Life Science, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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19
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Krishnamoorthy G. Fluorescence spectroscopy for revealing mechanisms in biology: Strengths and pitfalls. J Biosci 2018; 43:555-567. [PMID: 30002272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This article describes the basic principles of steady-state and time-resolved fluorescence. The formal equivalence of the two methodologies is described first, followed by the extra advantages of time-resolved methods in revealing population heterogeneity in complex systems encountered in biology. Several examples from the author's work are described in support of the above contention. Finally, several misinterpretations and pitfalls in the interpretation of fluorescence data and their remedy are described.
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Affiliation(s)
- G Krishnamoorthy
- Department of Biotechnology, Anna University, Chennai 600 025, India,
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20
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Abstract
Pseudomonas aeruginosa is an important human pathogen, the physiology and virulence of which are under the control of quorum sensing signals. These signals often have dual roles, functioning as toxins to some cells and as oxidative-stress protectors for their producer cells. Hence, their internal and external concentrations should be tightly controlled. In this study, we analyzed the interplay between the multidrug efflux transporters MexEF-OprN and MexG/HI-OpmD in quorum sensing of P. aeruginosa. We found that the two transporters have overlapping substrate specificities but different efficiencies. When overproduced, both MexEF-OprN and MexG/HI-OpmD provide clinical levels of resistance to diverse fluoroquinolones and protect P. aeruginosa against toxic phenazines. However, this similarity is enabled by synergistic interactions with the outer membrane. In hyperporinated cells, MexG/HI-OpmD is saturated by much lower concentrations of fluoroquinolones but is more efficient than MexEF-OprN in efflux of phenazines. Unlike MexEF-OprN, mutational inactivation of MexG/HI-OpmD reduces the levels of pyocyanin and makes P. aeruginosa cells hypersusceptible to phenazines. Our results further show that MexG binds pyocyanin, physically associates with MexHI, and represses the activity of the transporter, revealing a negative regulatory role of this protein. We conclude that differences in kinetic properties of transporters are critical to maintain proper intra- and extracellular concentrations of phenazines and other signaling molecules and that MexG/HI-OpmD controls the steady state in the synthesis and secretion of phenazines.
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Affiliation(s)
- David Wolloscheck
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Ganesh Krishnamoorthy
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Jennifer Nguyen
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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21
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Sahu S, Ila, Shankar B, Sathiyendiran M, Krishnamoorthy G. Molecular aggregation to obtain conformer specific enhanced emissions from a triple emissive ESIPT dye. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.11.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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22
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Sahu S, Das M, Bharti AK, Krishnamoorthy G. Proton transfer triggered proton transfer: a self-assisted twin excited state intramolecular proton transfer. Phys Chem Chem Phys 2018; 20:27131-27139. [DOI: 10.1039/c8cp03835j] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The double excited state intramolecular proton transfer (ESIPT) of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole (bis-HPTA) has been investigated and found to undergo a new type of proton transfer.
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Affiliation(s)
- Saugata Sahu
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - Minati Das
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | | | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
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23
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Bhatia S, Krishnamoorthy G, Udgaonkar JB. Site-specific time-resolved FRET reveals local variations in the unfolding mechanism in an apparently two-state protein unfolding transition. Phys Chem Chem Phys 2018; 20:3216-3232. [DOI: 10.1039/c7cp06214a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Using multi-site time-resolved FRET, it is shown that equilibrium unfolding of monellin is not only heterogeneous, but that the degree of non-cooperativity differs between the sole α-helix and different parts of the β-sheet.
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Affiliation(s)
- Sandhya Bhatia
- National Centre for Biological Sciences
- Tata Institute of Fundamental Research
- Bengaluru 560065
- India
| | | | - Jayant B. Udgaonkar
- National Centre for Biological Sciences
- Tata Institute of Fundamental Research
- Bengaluru 560065
- India
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24
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Nath S, Pathak SK, Pradhan B, Gupta RK, Reddy KA, Krishnamoorthy G, Achalkumar AS. A sensitive and selective sensor for picric acid detection with a fluorescence switching response. NEW J CHEM 2018. [DOI: 10.1039/c7nj05136k] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Low molecular weight organogelator for the detection of picric acid.
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Affiliation(s)
- Subrata Nath
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Suraj Kumar Pathak
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Balaram Pradhan
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Ravindra Kumar Gupta
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - K. Anki Reddy
- Department of Chemical Engineering
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
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25
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Biswas A, Mariam J, Kombrabail M, Narayan S, Krishnamoorthy G, Anand R. Site-Specific Fluorescence Dynamics To Probe Polar Arrest by Fob1 in Replication Fork Barrier Sequences. ACS Omega 2017; 2:7389-7399. [PMID: 30023550 PMCID: PMC6045349 DOI: 10.1021/acsomega.7b01117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/12/2017] [Indexed: 06/08/2023]
Abstract
Fob1 protein plays an important role in aging and maintains genomic stability by avoiding clashes between the replication and transcription machinery. It facilitates polar arrest by binding to replication fork barrier (RFB) sites, present within the nontranscribed spacer region of the ribosomal DNA. Here, we investigate the mechanism of unidirectional arrest by creating multiple prosthetic forks within the RFB, with fluorescent adenine analogue 2-aminopurine incorporated site-specifically in both the "permissible" and "nonpermissible" directions. The motional dynamics of the RFB-Fob1 complexes analyzed by fluorescence lifetime and fluorescence anisotropy decay kinetics shows that Fob1 adopts a clamp-lock model of arrest and causes stronger perturbation with the bases in the double-stranded region of the nonpermissible-directed forks over those of the permissible directed ones, thereby creating a polar barrier. Corroborative thermal melting studies reveal a skewed distribution of GC content within the RFB sequence that potentially assists in Fob1-mediated arrest.
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Affiliation(s)
- Anwesha Biswas
- Department
of Chemistry, Indian Institute of Technology
Bombay, Mumbai, Maharashtra 400076, India
| | - Jessy Mariam
- Department
of Chemistry, Indian Institute of Technology
Bombay, Mumbai, Maharashtra 400076, India
| | - Mamta Kombrabail
- Department
of Chemical Sciences, Tata Institute of
Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Satya Narayan
- Department
of Chemical Sciences, Tata Institute of
Fundamental Research, Mumbai, Maharashtra 400005, India
| | - G. Krishnamoorthy
- Department
of Chemistry, Indian Institute of Technology
Bombay, Mumbai, Maharashtra 400076, India
- Department
of Chemical Sciences, Tata Institute of
Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Ruchi Anand
- Department
of Chemistry, Indian Institute of Technology
Bombay, Mumbai, Maharashtra 400076, India
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26
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Westfall DA, Krishnamoorthy G, Wolloscheck D, Sarkar R, Zgurskaya HI, Rybenkov VV. Bifurcation kinetics of drug uptake by Gram-negative bacteria. PLoS One 2017; 12:e0184671. [PMID: 28926596 PMCID: PMC5604995 DOI: 10.1371/journal.pone.0184671] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 08/28/2017] [Indexed: 11/18/2022] Open
Abstract
Cell envelopes of many bacteria consist of two membranes studded with efflux transporters. Such organization protects bacteria from the environment and gives rise to multidrug resistance. We report a kinetic model that accurately describes the permeation properties of this system. The model predicts complex non-linear patterns of drug uptake complete with a bifurcation, which recapitulate the known experimental anomalies. We introduce two kinetic parameters, the efflux and barrier constants, which replace those of Michaelis and Menten for trans-envelope transport. Both compound permeation and efflux display transitions, which delineate regimes of efficient and inefficient efflux. The first transition is related to saturation of the transporter by the compound and the second one behaves as a bifurcation and involves saturation of the outer membrane barrier. The bifurcation was experimentally observed in live bacteria. We further found that active efflux of a drug can be orders of magnitude faster than its diffusion into a cell and that the efficacy of a drug depends both on its transport properties and therapeutic potency. This analysis reveals novel physical principles in the behavior of the cellular envelope, creates a framework for quantification of small molecule permeation into bacteria, and should invigorate structure-activity studies of novel antibiotics.
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Affiliation(s)
- David A. Westfall
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
| | - Ganesh Krishnamoorthy
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
| | - David Wolloscheck
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
| | - Rupa Sarkar
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
- * E-mail: (VVR); (HIZ)
| | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Stephenson Parkway, Norman, OK, United States of America
- * E-mail: (VVR); (HIZ)
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27
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Abstract
The effect of cucurbit-7-uril (CB-7) on a cationic mixture with same charge has been investigated by studying monocationic mixtures of 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP-b) and 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-c]pyridine (DMAPIP-c). The pKa of both the guests increases in CB-7. DMAPIP-b forms all three monocations in the ground and the excited states in aqueous as well as in CB-7 solution. However, CB-7 shifts the equilibrium more towards the less polar MC2 and MC3. On the other hand, DMAPIP-c exists only as MC1 and MC3 in aqueous solution, however, in CB-7 it exists not only as MC1 and MC3 but also as MC2 in CB-7 in the ground state. In the excited state, as in aqueous solution MC1 forms MC2 by biprotonic phototautomerism in CB-7. The association constants of monocations suggest a pyridyl nitrogen position dependence. All the MC-CB-7 complexes are optimized by density functional theory (DFT).
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Affiliation(s)
- Santosh Kumar Behera
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahti-781039, India.
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahti-781039, India.
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28
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Chakraborty H, Lentz BR, Kombrabail M, Krishnamoorthy G, Chattopadhyay A. Depth-Dependent Membrane Ordering by Hemagglutinin Fusion Peptide Promotes Fusion. J Phys Chem B 2017; 121:1640-1648. [DOI: 10.1021/acs.jpcb.7b00684] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- School
of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
| | - Barry R. Lentz
- Department
of Biochemistry and Biophysics and Program in Molecular and Cellular
Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | - Mamata Kombrabail
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhaba Road, Mumbai, India
| | - G. Krishnamoorthy
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhaba Road, Mumbai, India
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29
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Anandhakumar S, Krishnamoorthy G, Ramkumar K, Raichur A. Preparation of collagen peptide functionalized chitosan nanoparticles by ionic gelation method: An effective carrier system for encapsulation and release of doxorubicin for cancer drug delivery. Materials Science and Engineering: C 2017; 70:378-385. [DOI: 10.1016/j.msec.2016.09.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 08/18/2016] [Accepted: 09/03/2016] [Indexed: 02/09/2023]
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30
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Behera SK, Murkherjee A, Sadhuragiri G, Elumalai P, Sathiyendiran M, Kumar M, Mandal BB, Krishnamoorthy G. Aggregation induced enhanced and exclusively highly Stokes shifted emission from an excited state intramolecular proton transfer exhibiting molecule. Faraday Discuss 2017; 196:71-90. [DOI: 10.1039/c6fd00171h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The inner filter effect due to self-quenching dominates the normal emission of dyes at higher concentrations, which would limit their applications. Since normal emission was also observed with aggregation induced emission enhancement (AIEE) active excited state intramolecular proton transfer (ESIPT) exhibiting molecules, two new molecules are synthesized and studied to obtain normal emission free AIEE. The molecules are 4-(3-(benzo[d]thiazol-2-yl)-5-tert-butyl-4-hydroxybenzyl)-2-(benzo[d]thiazol-2-yl)-6-tert-butyl phenol (bis-HPBT) and its oxazole analogue (bis-HPBO). Of these molecules, bis-HPBT, which is weakly fluorescent in tetrahydrofuran solution, shows a sudden high enhancement in fluorescence upon addition of 70% water due to the formation of aggregates. Though the normal emission is also observed in tetrahydrofuran, it is completely eliminated in the aggregates, and the aggregates display exclusive tautomer emission. However, bis-HPBO does not emit such an exclusive tautomer emission in the water/tetrahydrofuran mixture. The enhancement in the fluorescence quantum yield of bis-HPBT in 70% water is ∼300 times higher than that in tetrahydrofuran. The modulated molecular structure of bis-HPBT is the cause of this outstanding AIEE. The observation of almost exclusive tautomer emission is a new additional advantage of AIEE from bis-HPBT over other ESIPT molecules. Since the tautomer emission is highly Stokes shifted, no overlap with the absorption spectrum occurs and therefore, the inner filter effect is averted. The aggregated structure acts as a good fluorescence chemosensor for metal ions as well as anions. The aggregated structure is cell permeable and can be used for cell imaging.
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Affiliation(s)
- Santosh Kumar Behera
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati – 781039
- India
| | - Anwesha Murkherjee
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati – 781039
- India
| | - G. Sadhuragiri
- School of Chemistry
- University of Hyderabad
- Hyderabad
- India
| | | | | | - Manishekhar Kumar
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati – 781039
- India
| | - Biman B. Mandal
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati – 781039
- India
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati – 781039
- India
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31
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Abstract
The anion sensitivity and the deprotonation nature of the nitrogenous analogues of 2-(2'-hydroxyphenyl)benzimidazole (HPBI) are investigated in a polar aprotic medium. It is observed that the substitution of pyridyl nitrogen enhances the anion sensitivity. However, despite the enhanced sensitivity of the nitrogenous analogues the deprotonation of these molecules in the presence of strong anions is less favored as compared to HPBI. This anomalous trend observed for the nitrogenous analogs is discussed and explained using theoretical calculations and experimental findings. It is also found that the sensitivity towards anions and the formation of anions also depend on the position of the pyridyl nitrogen.
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Affiliation(s)
- Saugata Sahu
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam-781039, India.
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32
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Sahay S, Krishnamoorthy G, Maji SK. Site-specific structural dynamics ofα-Synuclein revealed by time-resolved fluorescence spectroscopy: a review. Methods Appl Fluoresc 2016; 4:042002. [DOI: 10.1088/2050-6120/4/4/042002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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33
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Malakar A, Kumar M, Reddy A, Biswal HT, Mandal BB, Krishnamoorthy G. Aggregation induced enhanced emission of 2-(2'-hydroxyphenyl)benzimidazole. Photochem Photobiol Sci 2016; 15:937-48. [PMID: 27334264 DOI: 10.1039/c6pp00122j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this study, the aggregation induced emission enhancement (AIEE) of 2-(2'-hydroxyphenyl)benzimidazole (HPBI) is reported. To investigate the AIEE process of HPBI, absorption/fluorescence spectroscopy, fluorescence imaging and field emission scanning electron microscopy were employed. A comparative study with 2-phenylbenzimidazole (PBI) divulges the significance of the hydroxyl group in the AIEE process. Further, molecular dynamics simulations have been carried out with explicit solvent molecules to follow the aggregation process of HPBI with time. The obtained molecular dynamics simulation results not only predicted the formation of aggregates but also provided detailed insight and information on the molecular interactions. The cellular studies showed aggregates yield higher fluorescence in the visible region inside HeLa cells in comparison to monomeric compounds which failed to exhibit any visible fluorescence inside the cell. The obtained aggregates were further found to be biocompatible and therefore can be used for bio-imaging applications.
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Affiliation(s)
- Ashim Malakar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
| | - Manishekhar Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Anki Reddy
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Himadree T Biswal
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
| | - Biman B Mandal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
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Sahu S, Das M, Krishnamoorthy G. Switching between cis and trans anions of 2-(2'-hydroxyphenyl)benzimidazole: a molecular rotation perturbed by chemical stabilization. Phys Chem Chem Phys 2016; 18:11081-90. [PMID: 27051888 DOI: 10.1039/c5cp07949g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the fact that 2-(2'-hydroxyphenyl)benzimidazole (HPBI) exists as the cis and trans enol in neutral form, it was reported to exist only in the trans form upon deprotonation in an aqueous medium. It was also shown that the dianion formed in the ground state can be re-protonated to form the trans-anion in the excited state. In the present study, the cis-anion and dianion could be obtained upon proper stabilization in suitable environments. Switching between the cis and trans-anion was demonstrated to be possible by changing the environment. Theoretical calculations were performed to substantiate the existence of the cis-anion and dianion. In contrast to a literature report, it was shown that the 'OH' group deprotonates before the 'NH' group to form a monoanion not only in protic solvents but also in aprotic solvents.
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Affiliation(s)
- Saugata Sahu
- Department of chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India - 781039.
| | - Minati Das
- Department of chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India - 781039.
| | - G Krishnamoorthy
- Department of chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India - 781039.
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Behera SK, Sadhuragiri G, Elumalai P, Sathiyendiran M, Krishnamoorthy G. Exclusive excited state intramolecular proton transfer from a 2-(2′-hydroxyphenyl)benzimidazole derivative. RSC Adv 2016. [DOI: 10.1039/c6ra11780e] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The existence of trans-enol was made unviable by crafting a steric hindrance that stops the normal emission of bis-HPBI.
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Affiliation(s)
| | | | - Palani Elumalai
- School of Chemistry
- University of Hyderabad
- Hyderabad 500046
- India
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Mondal S, Kallianpur MV, Udgaonkar JB, Krishnamoorthy G. Molecular crowding causes narrowing of population heterogeneity and restricts internal dynamics in a protein. Methods Appl Fluoresc 2015. [DOI: 10.1088/2050-6120/4/1/014003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Chakraborty H, Haldar S, Chong PLG, Kombrabail M, Krishnamoorthy G, Chattopadhyay A. Depth-Dependent Organization and Dynamics of Archaeal and Eukaryotic Membranes: Development of Membrane Anisotropy Gradient with Natural Evolution. Langmuir 2015; 31:11591-11597. [PMID: 26445271 DOI: 10.1021/acs.langmuir.5b02760] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The lipid composition of archaea is unique and has been correlated with increased stability under extreme environmental conditions. In this article, we have focused on the evolution of membrane organization and dynamics with natural evolution. Dynamic anisotropy along the membrane normal (i.e., gradients of mobility, polarity, and heterogeneity) is a hallmark of fluid phase diester or diether phospholipid membranes. We monitored gradients of mobility, polarity, and heterogeneity along the membrane normal in membranes made of a representative archaeal lipid using a series of membrane depth-dependent fluorescent probes, and compared them to membranes prepared from a typical diether lipid from higher organisms (eukaryotes). Our results show that the representative dynamic anisotropy gradient along the membrane normal is absent in membranes made from archaeal lipids. We hypothesize that the dynamic gradient observed in membranes of diester and diether phospholipids is a consequence of natural evolution of membrane lipids in response to the requirement of carrying out complex cellular functions by membrane proteins.
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Affiliation(s)
- Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology , Uppal Road, Hyderabad 500 007, India
- School of Chemistry, Sambalpur University , Burla, Odisha 768 019, India
| | - Sourav Haldar
- CSIR-Centre for Cellular and Molecular Biology , Uppal Road, Hyderabad 500 007, India
| | - Parkson Lee-Gau Chong
- Department of Medical Genetics & Molecular Biochemistry, Temple University School of Medicine , Philadelphia, Pennsylvania 19140, United States
| | - Mamata Kombrabail
- Department of Chemical Sciences, Tata Institute of Fundamental Research , Homi Bhabha Road, Mumbai 400 005, India
| | - G Krishnamoorthy
- Department of Chemical Sciences, Tata Institute of Fundamental Research , Homi Bhabha Road, Mumbai 400 005, India
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Gödel C, Berer K, Krishnamoorthy G, Wekerle H. Alteration of the intestinal microbiota by short-time antibiosis protects mice from CNS-specific autoimmunity. J Neurol Sci 2015. [DOI: 10.1016/j.jns.2015.08.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Biswas A, Narayan S, Kallianpur MV, Krishnamoorthy G, Anand R. Mode of DNA binding with γ-butyrolactone receptor protein CprB from Streptomyces coelicolor revealed by site-specific fluorescence dynamics. Biochim Biophys Acta Gen Subj 2015; 1850:2283-92. [PMID: 26278022 DOI: 10.1016/j.bbagen.2015.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 07/16/2015] [Accepted: 08/12/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND The γ-butyrolactone (GBL) binding transcription factors in Streptomyces species are known for their involvement in quorum sensing where they control the expression of various genes initiating secondary metabolic pathways. The structurally characterized member of this family CprB from Streptomyces coelicolor had earlier been demonstrated to bind a multitude of sequences containing a specific binding signature. Though structural breakthrough has been obtained for its complex with a consensus DNA sequence there is, however a dearth of information regarding the overall and site specific dynamics of protein-DNA interaction. METHODS To delineate the effect of CprB on the bound DNA, changes in motional dynamics of the fluorescent probe 2-aminopurine were monitored at three conserved base positions (5th, 12th and 23rd) for two DNA sequences: the consensus and the biologically relevant cognate element, on complex formation. RESULTS The changes in lifetime and generalized order parameter revealed a similarity in the binding pattern of the protein to both sequences with greater dynamic restriction at the end positions, 5th and 23rd, as compared to the middle 12th position. Also differences within this pattern demonstrated the influence of even small changes in sequence on protein interactions. CONCLUSIONS Here the study of motional dynamics was instrumental in establishing a structural footprint for the cognate DNA sequence and explaining the dynamics for the consensus DNA from structural correspondence. GENERAL SIGNIFICANCE Motional dynamics can be a powerful tool to efficiently study the mode of DNA binding to proteins that interact differentially with a plethora of DNA sequences, even in the absence of structural breakthrough.
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Affiliation(s)
- Anwesha Biswas
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Satya Narayan
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Mamata V Kallianpur
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - G Krishnamoorthy
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India.
| | - Ruchi Anand
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India.
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Bavithra S, Sugantha Priya E, Selvakumar K, Krishnamoorthy G, Arunakaran J. Effect of Melatonin on Glutamate: BDNF Signaling in the Cerebral Cortex of Polychlorinated Biphenyls (PCBs)-Exposed Adult Male Rats. Neurochem Res 2015. [PMID: 26224288 DOI: 10.1007/s11064-015-1677-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Various epidemiological survey suggests that the central nervous system is the target for many environmental contaminants. One among them is Aroclor 1254, a mixture of polychlorinated biphenyls (PCBs) which explore a spectrum of biochemical and neurotoxic responses in humans and laboratory animals. Learning and motor coordination deficits are the profound effects of PCBs which may be related to cerebral dysfunction. The aim of the study is to elicit the protective effect of melatonin (Mel), a potent, blood brain permeable antioxidant against the effect of Aroclor 1254 on the signaling of glutamate-principal excitatory neurotransmitter and brain derived neurotrophic factor (BDNF) in the cerebral cortex of adult rats which plays a key role in brain functions. Adult male Wistar rats were grouped into four and treated intraperitonealy (i.p) Group I with corn oil (Control), Group II with PCBs (2 mg/kg/bwt), Group III with PCBs + Mel (2 mg/kg/bwt + 5 mg/kg/bwt) and Group IV with Mel (5 mg/kg/bwt). The protein expression of glutamate signaling molecules and mRNA expressions of GLAST, BDNF signaling molecules were analyzed. The results suggest that simultaneous melatonin treatment significantly attenuated the NMDA receptor mediated glutamate excitotoxicity and protects the inhibition of BDNF signaling caused by PCBs exposure in cerebral cortex of adult male rats. Schematic pathway illustrating the proposed mechanism by which melatonin protects against A1254 mediated glutamate induced neurodegeneration in the cerebral cortex of adult male rats. PCBs induced neurodegeneration is caused by the overactivation of NMDAR, followed by the activation of voltage dependent calcium channels leading to the increase in intracellular Ca(2+) that stimulates calpain. Calpain inturn inhibits the PKA α and neurtrophin BDNF, its receptor and downstream signaling MAPK pathway leading to neurodegeneration. Melatonin had scavenged the ROS produced by PCBS and decreased the NMDAR expression which inturn protected the cells from neurodegeneration.
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Affiliation(s)
- S Bavithra
- Department of Endocrinology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Chennai, 600 113, India
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Mishra A, Sahu S, Tripathi S, Krishnamoorthy G. Photoinduced intramolecular charge transfer in trans-2-[4'-(N,N-dimethylamino)styryl]imidazo[4,5-b]pyridine: effect of introducing a C[double bond, length as m-dash]C double bond. Photochem Photobiol Sci 2015; 13:1476-86. [PMID: 25103414 DOI: 10.1039/c4pp00237g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The spectral characteristics of trans-2-[4'-(N,N-dimethylamino)styryl]imidazo[4,5-b]pyridine (t-DMASIP-b) have been investigated using absorption and fluorescence techniques, and compared with 2-(4'-N,N-dimethylamino)imidazo[4,5-b]pyridine (DMAPIP-b). The study reveals that introduction of a C[double bond, length as m-dash]C double bond strongly perturbs the photophysics of the system. Unlike DMAPIP-b, t-DMASIP-b emits a single emission in aprotic and protic solvents. The emission occurs from the locally excited state in nonpolar solvents and from a planar intramolecular charge transfer (PICT) state in polar solvents. Multiple linear regression analysis suggests that among the different solvent parameters, the dipolar interaction contributes more to the stabilization of the system in both the ground and excited states. Theoretical calculations suggest that, unlike in DMAPIP-b, proton coupled twisted intramolecular charge transfer (TICT) emission does not occur in t-DMASIP-b. The higher quantum yield obtained in the viscous solvent glycerol is attributed to the restriction of the twisting of the olefinic bond. The photoirradiation of t-DMASIP-b shows that isomerization takes place in all solvents, including viscous glycerol. The theoretically simulated potential energy surface shows that isomerization occurs via a phantom state, which is a nonradiative process. The rise in temperature favors the photoisomerization, thus, the fluorescence quantum yield decreases. The prototropic study indicates that, unlike in DMAPIP-b, the protonation takes place at different places to form the monocations.
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Affiliation(s)
- Anasuya Mishra
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
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Malakar A, Krishnamoorthy G. Dual emission from 2-(4'-N,N-dimethylaminophenyl)pyridoimidazole-nanoparticle composite: effect of β-cyclodextrin. J Colloid Interface Sci 2015; 443:23-9. [PMID: 25528531 DOI: 10.1016/j.jcis.2014.11.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 11/17/2014] [Accepted: 11/20/2014] [Indexed: 11/26/2022]
Abstract
The interactions of the silver nanoparticles with 2-(4'-N,N-dimethylaminophenyl)benzimidazole and its nitrogen substituted analogues, 2-(4'-N,N-dimethylaminophenyl)pyridoimidazoles are investigated by absorption, steady-state and time resolved fluorescence, field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) techniques. The surface plasmon resonance band, the FESEM and the TEM images of the particles suggest that the fluorophores can stabilize the nanoparticles even in the absence of any other stabilizing agent. On the other hand, in the absence of fluorophores the nanoparticles are unstable and coagulate. In contrary to the earlier literature reports that interactions of nanoparticles with intramolecular charge transfer (ICT) or twisted intramolecular charge transfer (TICT) species quenches their fluorescence, to the best of our knowledge, the first ever formation of TICT state by interactions of nanoparticles with the fluorophores is observed. The formation of TICT state in 2-(4'-N,N-dimethylaminophenyl)pyridoimidazoles results in dual emission. The TICT emissions from the nanoparticle-fluorophore complexes are weak. But the emissions become prominent upon complexation with β-cyclodextrin.
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Affiliation(s)
- Ashim Malakar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - G Krishnamoorthy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
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Mishra A, Malakar A, Biswal HT, Barman MK, Krishnamoorthy G. Interactions of a few azole derivatives with a transport protein: role of heteroatoms. J Mol Recognit 2015; 28:299-305. [DOI: 10.1002/jmr.2444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Anasuya Mishra
- Department of Chemistry; Indian Institute of Technology Guwahati; Guwahati 781039 India
| | - Ashim Malakar
- Department of Chemistry; Indian Institute of Technology Guwahati; Guwahati 781039 India
| | - Himadree T. Biswal
- Department of Chemistry; Indian Institute of Technology Guwahati; Guwahati 781039 India
| | - Monoj K. Barman
- Department of Chemistry; Indian Institute of Technology Guwahati; Guwahati 781039 India
| | - G. Krishnamoorthy
- Department of Chemistry; Indian Institute of Technology Guwahati; Guwahati 781039 India
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Abstract
Logic gates with different radixes have been constructed using a biologically active molecule, 2-(4′-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP-b).
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Affiliation(s)
- Saugata Sahu
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - Timir Baran Sil
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - Minati Das
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
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Abstract
The mechanism for the dual emission of 2-(4′-N,N-dimethylaminophenyl)imidazo[4,5-c]pyridine (DMAPIP-c) in protic solvents was investigated by synthesizing and studying its analogues.
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Affiliation(s)
| | - G. Krishnamoorthy
- Department of Chemistry
- Indian Institute of Technology Guwahati
- Guwahati
- India
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Biswas A, Patwari GN, Krishnamoorthy G, Anand R. Studying Ligand Binding and Site-Specific Mode of DNA Binding by Gamma-Butyrolactone Receptor Protein CprB from Streptomyces Coelicolor A3(2) using Two Different Fluorescence Techniques. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Behera SK, Karak A, Krishnamoorthy G. Photophysics of 2-(4'-amino-2'-hydroxyphenyl)-1H-imidazo-[4,5-c]pyridine and its analogues: intramolecular proton transfer versus intramolecular charge transfer. J Phys Chem B 2014; 119:2330-44. [PMID: 25337987 DOI: 10.1021/jp5064808] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photophysical characteristics of 2-(4'-amino-2'-hydroxyphenyl)-1H-imidazo-[4,5-c]pyridine (AHPIP-c) have been studied in various aprotic and protic solvents using UV-visible, steady state fluorescence and time-resolved fluorescence spectroscopic techniques. To comprehend the competition between the intramolecular charge transfer (ICT) and the excited state intramolecular proton transfer (ESIPT) processes, the photophysical properties of 2-(4'-amino-2'-methoxyphenyl)-1H-imidazo-[4,5-c]pyridine (AMPIP-c) and 2-(4'-aminophenyl)-1H-imidazo-[4,5-c]pyridine (APIP-c) were also investigated. Though APIP-c displays twisted ICT (TICT) emission in protic solvents, AHPIP-c exhibits normal and tautomer emissions in aprotic as well as in protic solvents due to ESIPT. However, the methoxy derivative, AMPIP-c, emits weak TICT fluorescence in methanol.
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Affiliation(s)
- Santosh Kumar Behera
- Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781039, India
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Nischwitz S, Faber H, Sämann PG, Domingues HS, Krishnamoorthy G, Knop M, Müller-Sarnowski F, Yassouridis A, Weber F. Interferon β-1a reduces increased interleukin-16 levels in multiple sclerosis patients. Acta Neurol Scand 2014; 130:46-52. [PMID: 24571587 DOI: 10.1111/ane.12215] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2013] [Indexed: 12/14/2022]
Abstract
OBJECTIVES There is convergent evidence for an important role of interleukin-16 (IL-16) in the pathogenesis of multiple sclerosis (MS). IL-16 serves as a chemoattractant for different immune cells that are involved in developing lesions. Here, we compared IL-16 levels of MS patients and controls and addressed the long-term effect of IFN-β, the most common immunomodulatory MS therapy, on IL-16 serum levels in MS patients over 2 years. Beyond this, we analysed the expression of IL-16 in two CD4(+) T-cell subsets, Th1 and Th17 cells, which are important autoimmune mediators and affected by IFN-β treatment, derived from myelin-specific T-cell transgenic mice. MATERIALS AND METHODS IL-16 serum levels of 17 controls and of 16 MS patients before therapy and at months 1, 2, 3, 6, 9, 12 and 24 during IFN-β1a therapy were determined by ELISA. MRI was performed before therapy, at months 12 and 24. IL-16 expression of in vitro differentiated murine myelin oligodendrocyte glycoprotein (MOG)-specific Th1 and Th17 cells was quantified by real-time PCR. RESULTS Before therapy, MS patients showed significantly elevated IL-16 levels compared with controls irrespective of disease activity determined by MRI. Therapy with IFN-β1a led to a significant linear decrease in IL-16 serum levels beginning after 2 months. MOG-specific Th17 cells expressed more IL-16 than Th1 cells. CONCLUSIONS Reduction in increased IL-16 levels may be of relevance for the therapeutic effect of IFN-β1a in MS. Easily accessible IL-16 serum levels hold a potential as biomarker of treatment efficacy in MS.
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Affiliation(s)
- S. Nischwitz
- RG Inflammatory Disorders of the CNS, Neurology; Max Planck Institute of Psychiatry; Munich Germany
| | - H. Faber
- RG Inflammatory Disorders of the CNS, Neurology; Max Planck Institute of Psychiatry; Munich Germany
| | - P. G. Sämann
- RG Neuroimaging; Max Planck Institute of Psychiatry; Munich Germany
| | - H. S. Domingues
- Max Planck Institute of Neurobiology; Martinsried Germany
- Instituto de Biologia Molecular e Celular R. Campo Alegre; Porto Portugal
| | | | - M. Knop
- RG Inflammatory Disorders of the CNS, Neurology; Max Planck Institute of Psychiatry; Munich Germany
| | - F. Müller-Sarnowski
- RG Inflammatory Disorders of the CNS, Neurology; Max Planck Institute of Psychiatry; Munich Germany
| | - A. Yassouridis
- RG Biostatistics; Max Planck Institute of Psychiatry; Munich Germany
| | - F. Weber
- RG Inflammatory Disorders of the CNS, Neurology; Max Planck Institute of Psychiatry; Munich Germany
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Chipem FAS, Behera SK, Krishnamoorthy G. Excited state proton transfer of 2-(2′-hydroxyphenyl)benzimidazole and its nitrogen substituted analogues in bovine serum albumin. Photochem Photobiol Sci 2014; 13:1297-304. [DOI: 10.1039/c4pp00099d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Sahay S, Anoop A, Krishnamoorthy G, Maji SK. Site-Specific Fluorescence Dynamics of α-Synuclein Fibrils Using Time-Resolved Fluorescence Studies: Effect of Familial Parkinson’s Disease-Associated Mutations. Biochemistry 2014; 53:807-9. [DOI: 10.1021/bi401543z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Shruti Sahay
- Department
of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
| | - A. Anoop
- Department
of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
| | - G. Krishnamoorthy
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Samir K. Maji
- Department
of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
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