1
|
Liang X, Deng H, Bai Y, Fan TP, Zheng X, Cai Y. Highly efficient biosynthesis of spermidine from L-homoserine and putrescine using an engineered Escherichia coli with NADPH self-sufficient system. Appl Microbiol Biotechnol 2022; 106:5479-5493. [PMID: 35931895 DOI: 10.1007/s00253-022-12110-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/21/2022] [Accepted: 07/27/2022] [Indexed: 11/30/2022]
Abstract
Spermidine is an important polyamine that can be used for the synthesis of various bioactive compounds in the food and pharmaceutical fields. In this study, a novel efficient whole-cell biocatalytic method with an NADPH self-sufficient cycle for spermidine biosynthesis was designed and constructed by co-expressing homoserine dehydrogenase (HSD), carboxyspermidine dehydrogenase (CASDH), and carboxyspermidine decarboxylase (CASDC). First, the enzyme-substrate coupled cofactor regeneration system from co-expression of NADP+-dependent ScHSD and NADPH-dependent AfCASDH exactly provides an efficient method for cofactor cycling. Second, we identified and characterized a putative CASDC with high decarboxylase activity from Butyrivibrio crossotus DSM 2876; it showed an optimum temperature of 35 °C and an optimum pH of 7.0, which make it better suited for the designed synthetic route. Subsequently, the protein expression level of each enzyme was optimized through the variation of the gene copy number, and a whole-cell catalyst with high catalytic efficiency was constructed successfully. Finally, a yield of 28.6 mM of spermidine was produced in a 1-L scale of E. coli whole-cell catalytic system with a 95.3% molar conversion rate after optimization of temperature, the ratio of catalyst-to-substrate, and the amount of NADP+, and a productivity of 0.17 g·L-1·h-1 was achieved. In summary, this novel pathway of constructing a whole-cell catalytic system from L-homoserine and putrescine could provide a green alternative method for the efficient synthesis of spermidine. KEY POINTS: • A novel pathway for spermidine biosynthesis was developed in Escherichia coli. • The enzyme-substrate coupled system provides an NADPH self-sufficient cycle. • Spermidine with 28.6 mM was obtained using an optimized whole-cell system.
Collapse
Affiliation(s)
- Xinxin Liang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Huaxiang Deng
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China
| | - Yajun Bai
- College of Life Sciences, Northwest University, Xi'an, 710069, Shanxi, China
| | - Tai-Ping Fan
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1T, UK
| | - Xiaohui Zheng
- College of Life Sciences, Northwest University, Xi'an, 710069, Shanxi, China.
| | - Yujie Cai
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
| |
Collapse
|
2
|
Abstract
In recent years, structured phospholipids (SPLs), which are modified phospholipids (PLs), have attracted more attention due to their great potential for application in the field of pharmacy, food, cosmetics, and health. SPLs not only possess enhanced chemical, physical and nutritional properties, but also present superior bioavailability in comparison with other lipid forms, such as triacylglycerols, which make SPLs become more competitive carriers to increase the absorption of the specific fatty acids in the body. Compared with chemical-mediated SPLs, the process of enzyme-mediated SPLs has the advantages of high product variety, high substrate selectivity, and mild operation conditions. Both lipases and phospholipases can be used in the enzymatic production of SPLs, and the main reaction type contains esterification, acidolysis, and transesterification. During the preparation, reaction medium, acyl migration, water content/activity, substrates and enzymes, and some other parameters have significant effects on the production and purity of the desired PLs products. In this paper, the progress in enzymatic modification of PLs over the last 20 years is reviewed. Reaction types and characteristic parameters are summarized in detail and the parameters affecting acyl migration are first discussed to give the inspiration to optimize the enzyme-mediated SPLs preparation. To expand the application of enzyme-mediated SPLs in the future, the prospect of further study on SPLs is also proposed at the end of the paper.
Collapse
|
3
|
Enhancing Soluble Expression of Phospholipase B for Efficient Catalytic Synthesis of L-Alpha-Glycerylphosphorylcholine. Catalysts 2022. [DOI: 10.3390/catal12060650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Phospholipase B (PLB) harbors three distinct activities with broad substrate specificities and application fields. Its hydrolyzing of sn-1 and sn-2 acyl ester bonds enables it to catalyze the production of L-alpha-glycerylphosphorylcholine (L-α-GPC) from phosphatidylcholine (PC) without speed-limiting acyl migration. This work was intended to obtain high-level active PLB and apply it to establish an efficient system for L-α-GPC synthesis. PLB from Pseudomonas fluorescens was co-expressed with five different molecular chaperones, including trigger factor (Tf), GroEL-GroES (GroELS), DnaK-DnaJ-GrpE (DnaKJE), GroELS and DnaKJE, or GroELS and Tf or fused with maltose binding protein (MBP) in Escherichia coli BL21(DE3) to improve PLB expression. PLB with DnaKJE-assisted expression exhibited the highest catalytic activity. Further optimization of the expression conditions identified an optimal induction OD600 of 0.8, IPTG concentration of 0.3 mmol/L, induction time of 9 h, and temperature of 25 °C. The PLB activity reached a maximum of 524.64 ± 3.28 U/mg under optimal conditions. Subsequently, to establish an efficient PLB-catalyzed system for L-α-GPC synthesis, a series of organic-aqueous mixed systems and surfactant-supplemented aqueous systems were designed and constructed. Furthermore, the factors of temperature, reaction pH, metal ions, and substrate concentration were further systematically identified. Finally, a high yield of 90.50 ± 2.21% was obtained in a Span 60-supplemented aqueous system at 40 °C and pH 6.0 with 0.1 mmol/L of Mg2+. The proposed cost-effective PLB production and an environmentally friendly PLB-catalyzed system offer a candidate strategy for the industrial production of L-α-GPC.
Collapse
|
4
|
Ali F, Manzoor U, Khan FI, Lai D, Khan MKA, Chandrashekharaiah KS, Singh LR, Dar TA. Effect of polyol osmolytes on the structure-function integrity and aggregation propensity of catalase: A comprehensive study based on spectroscopic and molecular dynamic simulation measurements. Int J Biol Macromol 2022; 209:198-210. [PMID: 35395280 DOI: 10.1016/j.ijbiomac.2022.04.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/18/2022] [Accepted: 04/03/2022] [Indexed: 01/24/2023]
Abstract
Owing to the ability of catalase to function under oxidative stress vis-à-vis its industrial importance, the structure-function integrity of the enzyme is of prime concern. In the present study, polyols (glycerol, sorbitol, sucrose, xylitol), were evaluated for their ability to modulate structure, activity and aggregation of catalase using in vitro and in silico approaches. All polyols increased catalase activity by decreasing Km and increasing Vmax resulting in enhanced catalytic efficiency (kcat/Km) of the enzyme, with glycerol being the most efficient with a kcat/Km increase from 4.38 × 104 mM-1 S-1 (control) to 5.8 × 105 mM-1 S-1. Correlatively with this, enhanced secondary structure with reduced hydrophobic exposure was observed in all polyols. Furthermore, increased stability, with an increase in melting temperature by 15.2 °C, and almost no aggregation was observed in glycerol. Overall, ability to regulate structure-function integrity and aggregation propensity was highest for glycerol and lowest for xylitol. Simulation studies were performed involving structural dynamics measurements, principal component analysis and free energy landscape analysis. Altogether, all polyols were stabilizing in nature and glycerol, in particular, has potential to efficiently prevent not only the antioxidant defense system but also might serve as a stability aid during industrial processing of catalase.
Collapse
Affiliation(s)
- Fasil Ali
- Department of Studies and Research in Biochemistry, Jnana Kaveri Campus, Mangalore University, Karnataka 571232, India
| | - Usma Manzoor
- Department of Clinical Biochemistry, University of Kashmir, Srinagar 190006, Jammu and Kashmir, India
| | - Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Md Khurshid A Khan
- School of Life Sciences, B. S. Abdur Rahman Crescent Institute of Science and Technology, Vandalur, Chennai 600 048, Tamil Nadu, India
| | - K S Chandrashekharaiah
- Department of Studies and Research in Biochemistry, Jnana Kaveri Campus, Mangalore University, Karnataka 571232, India
| | | | - Tanveer Ali Dar
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
| |
Collapse
|
5
|
Khan FI, Rehman MT, Sameena F, Hussain T, AlAjmi MF, Lai D, Khan MKA. Investigating the binding mechanism of topiramate with bovine serum albumin using spectroscopic and computational methods. J Mol Recognit 2022; 35:e2958. [PMID: 35347772 DOI: 10.1002/jmr.2958] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/20/2022] [Accepted: 03/28/2022] [Indexed: 11/10/2022]
Abstract
Various spectroscopic techniques involving fluorescence spectroscopy, circular dichroism (CD), and computational approaches were used to elucidate the molecular aspects of interaction between the antiepileptic drug topiramate and the multifunctional transport protein bovine serum albumin (BSA) under physiological conditions. Topiramate quenched BSA fluorescence in a static quenching mode, according to the Stern-Volmer quenching constant (Ksv ) data derived from fluorescence spectroscopy for the topiramate-BSA complex. The binding constant was also used to calculate the binding affinity for the topiramate-BSA interaction. Fluorescence and circular dichroism experiments demonstrate that the protein's tertiary structure is affected by the microenvironmental alterations generated by topiramate binding to BSA. To establish the exact binding site, interacting residues, and interaction forces involved in the binding of topiramate to BSA, molecular modeling and simulation approaches were used. According to the MMPBSA calculations, the average binding energy between topiramate and BSA is -421.05 kJ/mol. Topiramate was discovered to have substantial interactions with BSA, changing the structural dynamic and Gibbs free energy landscape patterns.
Collapse
Affiliation(s)
- Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Md Tabish Rehman
- Department of Pharmacognosy, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh, Saudi Arabia
| | - Fathima Sameena
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and technology, GST Road, Vandalur, Chennai
| | - Tabish Hussain
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mohamed F AlAjmi
- Department of Pharmacognosy, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh, Saudi Arabia
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Md Khurshid Alam Khan
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and technology, GST Road, Vandalur, Chennai
| |
Collapse
|
6
|
Khan FI, Lobb KA, Lai D. The Molecular Basis of the Effect of Temperature on the Structure and Function of SARS-CoV-2 Spike Protein. Front Mol Biosci 2022; 9:794960. [PMID: 35463957 PMCID: PMC9019816 DOI: 10.3389/fmolb.2022.794960] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/27/2022] [Indexed: 12/14/2022] Open
Abstract
The remarkable rise of the current COVID-19 pandemic to every part of the globe has raised key concerns for the current public healthcare system. The spike (S) protein of SARS-CoV-2 shows an important part in the cell membrane fusion and receptor recognition. It is a key target for vaccine production. Several researchers studied the nature of this protein under various environmental conditions. In this work, we applied molecular modeling and extensive molecular dynamics simulation approaches at 0°C (273.15 K), 20°C (293.15 K), 40°C (313.15 K), and 60°C (333.15 K) to study the detailed conformational alterations in the SARS-CoV-2 S protein. Our aim is to understand the influence of temperatures on the structure, function, and dynamics of the S protein of SARS-CoV-2. The structural deviations, and atomic and residual fluctuations were least at low (0°C) and high (60°C) temperature. Even the internal residues of the SARS-CoV-2 S protein are not accessible to solvent at high temperature. Furthermore, there was no unfolding of SARS-CoV-2 spike S reported at higher temperature. The most stable conformations of the SARS-CoV-2 S protein were reported at 20°C, but the free energy minimum region of the SARS-CoV-2 S protein was sharper at 40°C than other temperatures. Our findings revealed that higher temperatures have little or no influence on the stability and folding of the SARS-CoV-2 S protein.
Collapse
Affiliation(s)
- Faez Iqbal Khan
- Department of Biological Sciences, School of Science, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu, China
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Kevin A. Lobb
- Department of Chemistry, Rhodes University, Grahamstown, South Africa
- *Correspondence: Dakun Lai, ; Kevin A. Lobb,
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- *Correspondence: Dakun Lai, ; Kevin A. Lobb,
| |
Collapse
|
7
|
Khan FI, Kang T, Ali H, Lai D. Remdesivir Strongly Binds to RNA-Dependent RNA Polymerase, Membrane Protein, and Main Protease of SARS-CoV-2: Indication From Molecular Modeling and Simulations. Front Pharmacol 2021; 12:710778. [PMID: 34305617 PMCID: PMC8293383 DOI: 10.3389/fphar.2021.710778] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 06/15/2021] [Indexed: 12/28/2022] Open
Abstract
Development of new drugs is a time-taking and expensive process. Comprehensive efforts are being made globally toward the search of therapeutics against SARS-CoV-2. Several drugs such as remdesivir, favipiravir, ritonavir, and lopinavir have been included in the treatment regimen and shown effective results in several cases. Among the existing broad-spectrum antiviral drugs, remdesivir is found to be more effective against SARS-CoV-2. Remdesivir has broad-spectrum antiviral action against many single-stranded RNA viruses including pathogenic SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV). In this study, we proposed that remdesivir strongly binds to membrane protein (Mprotein), RNA-dependent RNA polymerase (RDRP), and main protease (Mprotease) of SARS-CoV-2. It might show antiviral activity by inhibiting more than one target. It has been found that remdesivir binds to Mprotease, Mprotein, and RDRP with -7.8, -7.4, and -7.1 kcal/mol, respectively. The structure dynamics study suggested that binding of remdesivir leads to unfolding of RDRP. It has been found that strong binding of remdesivir to Mprotein leads to decrease in structural deviations and gyrations. Additionally, the average solvent-accessible surface area of Mprotein decreases from 127.17 to 112.12 nm2, respectively. Furthermore, the eigenvalues and the trace of the covariance matrix were found to be low in case of Mprotease-remdesivir, Mprotein-remdesivir, and RDRP-remdesivir. Binding of remdesivir to Mprotease, Mprotein, and RDRP reduces the average motions in protein due to its strong binding. The MMPBSA calculations also suggested that remdesivir has strong binding affinity with Mprotein, Mprotease, and RDRP. The detailed analysis suggested that remdesivir has more than one target of SARS-CoV-2.
Collapse
Affiliation(s)
- Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Tongzhou Kang
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Haider Ali
- Faculty of Medicine, International Ala-Too University, Bishkek, Kyrgyzstan
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| |
Collapse
|
8
|
Khan FI, Song H, Hassan F, Tian J, Tang L, Lai D, Juan F. Impact of amino acid substitutions on the behavior of a photoactivatable near infrared fluorescent protein PAiRFP1. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 253:119572. [PMID: 33631627 DOI: 10.1016/j.saa.2021.119572] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 01/16/2021] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
A photoactivatable near-infrared fluorescent protein (NIR-FP) PAiRFP1 has been developed by 15 amino acid substitutions in its nonfluorescent template Agp2. In our previous communication, we investigated the role of three amino acids in PHY domain distal from BV molecule. The impact of the twelve amino acids in GAF domain, especially five residues near BV-binding pocket is unclear. In this paper, PCR based reverse mutagenesis, spectroscopic methods, molecular modelling and simulations have been employed to explore the roles of these substitutions during the molecular evolution of PAiRFP1. It was found that the residue L163 is important for protein folding in PAiRFP1. The residues F244 and C280 exerted remarkable effects on molar extinction coefficient, NIR fluorescence quantum yield, molecular brightness, fluorescence fold, and dark recovery rate. The residues F244 and V276 modulate the maximum absorption and emission peak position. The reverse mutant L168M exhibited a higher fluorescence fold than PAiRFP1. Additionally, the reverse mutants V203A, V294E, S218G and D127G possessed better spectral properties than PAiRFP1. This study is important for the rational design of a better BphP-based photoactivatable NIR-FPs.
Collapse
Affiliation(s)
- Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Honghong Song
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Fakhrul Hassan
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Jing Tian
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Lixia Tang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China.
| | - Feng Juan
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
| |
Collapse
|
9
|
Liang S, Wang S, Meng Y, Sun C. Enzymatic preparation of glycerophosphatilcholine catalyzed by combinational phospholipases: a comparative study of concerted versus stepwise catalysis. RSC Adv 2020; 10:38727-38735. [PMID: 35518402 PMCID: PMC9057254 DOI: 10.1039/d0ra07012b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/13/2020] [Indexed: 12/16/2022] Open
Abstract
Glycerophosphatilcholine (GPC) is widely applied in medical, pharmaceutical, food and cosmetic industries. Due to the lack of natural resources, enzymatic preparation of GPC has been explored in recent years. This study aimed to investigate and compare the effects of different addition methods of combinational phospholipases (PLA1 and PLA2) and various process parameters (time, temperature, pH, substrate concentrate, enzyme load, and stirring rate) on the preparation of GPC. The results showed that compared with concerted catalysis, the catalytic efficiency of adding PLA2 and then PLA1 (PLA2 → A1) was higher, whereas that of adding PLA1 and then PLA2 was lower. The main reason might be that the method of PLA2 → A1 could reduce acyl migration and the competition between PLA1 and PLA2, which was beneficial to improve the GPC yield and shorten the reaction time. This paper could provide a novel approach for the future preparation of GPC catalyzed by combinational phospholipases. The addition methods of PLA1 and PLA2 had a vital influence on the preparation of GPC, and the method of PLA2 → A1 was the most effective.![]()
Collapse
Affiliation(s)
- Shaohua Liang
- College of Food Science and Engineering, Henan University of Technology Lianhua Road 100 Zhengzhou 450001 Henan Province P. R. China +86-371-67758022 +86-371-67758022
| | - Shukun Wang
- College of Food Science and Engineering, Henan University of Technology Lianhua Road 100 Zhengzhou 450001 Henan Province P. R. China +86-371-67758022 +86-371-67758022
| | - Yannan Meng
- College of Food Science and Engineering, Henan University of Technology Lianhua Road 100 Zhengzhou 450001 Henan Province P. R. China +86-371-67758022 +86-371-67758022
| | - Cong Sun
- College of Food Science and Engineering, Henan University of Technology Lianhua Road 100 Zhengzhou 450001 Henan Province P. R. China +86-371-67758022 +86-371-67758022
| |
Collapse
|
10
|
Khan FI, Hassan F, Anwer R, Juan F, Lai D. Comparative Analysis of Bacteriophytochrome Agp2 and Its Engineered Photoactivatable NIR Fluorescent Proteins PAiRFP1 and PAiRFP2. Biomolecules 2020; 10:biom10091286. [PMID: 32906690 PMCID: PMC7564321 DOI: 10.3390/biom10091286] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/27/2020] [Accepted: 09/04/2020] [Indexed: 12/11/2022] Open
Abstract
Two photoactivatable near infrared fluorescent proteins (NIR FPs) named “PAiRFP1” and “PAiRFP2” are formed by directed molecular evolution from Agp2, a bathy bacteriophytochrome of Agrobacterium tumefaciens C58. There are 15 and 24 amino acid substitutions in the structure of PAiRFP1 and PAiRFP2, respectively. A comprehensive molecular exploration of these bacteriophytochrome photoreceptors (BphPs) are required to understand the structure dynamics. In this study, the NIR fluorescence emission spectra for PAiRFP1 were recorded upon repeated excitation and the fluorescence intensity of PAiRFP1 tends to increase as the irradiation time was prolonged. We also predicted that mutations Q168L, V244F, and A480V in Agp2 will enhance the molecular stability and flexibility. During molecular dynamics (MD) simulations, the average root mean square deviations of Agp2, PAiRFP1, and PAiRFP2 were found to be 0.40, 0.49, and 0.48 nm, respectively. The structure of PAiRFP1 and PAiRFP2 were more deviated than Agp2 from its native conformation and the hydrophobic regions that were buried in PAiRFP1 and PAiRFP2 core exposed to solvent molecules. The eigenvalues and the trace of covariance matrix were found to be high for PAiRFP1 (597.90 nm2) and PAiRFP2 (726.74 nm2) when compared with Agp2 (535.79 nm2). It was also found that PAiRFP1 has more sharp Gibbs free energy global minima than Agp2 and PAiRFP2. This comparative analysis will help to gain deeper understanding on the structural changes during the evolution of photoactivatable NIR FPs. Further work can be carried out by combining PCR-based directed mutagenesis and spectroscopic methods to provide strategies for the rational designing of these PAiRFPs.
Collapse
Affiliation(s)
- Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China;
| | - Fakhrul Hassan
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China; (F.H.); (F.J.)
| | - Razique Anwer
- Department of Pathology, College of Medicine, Imam Mohammad ibn Saud Islamic University (IMSIU), Riyadh 13317, Saudi Arabia;
| | - Feng Juan
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China; (F.H.); (F.J.)
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China;
- Correspondence: ; Tel.: +86-182-0052-9516
| |
Collapse
|
11
|
Mechanistic insights into the urea-induced denaturation of human sphingosine kinase 1. Int J Biol Macromol 2020; 161:1496-1505. [PMID: 32771517 DOI: 10.1016/j.ijbiomac.2020.07.280] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/04/2020] [Accepted: 07/18/2020] [Indexed: 12/17/2022]
Abstract
Sphingosine kinase 1 (SphK1) plays a significant role in various cellular processes, including cell proliferation, apoptosis, and angiogenesis. SphK1 is considered as an attractive target for drug development owing to its connection with several diseases, including cancer. In the current work, the urea-induced unfolding of SphK1 was performed at pH 8.0 and 25 °C using CD and fluorescence spectroscopy. SphK1 follows a biphasic unfolding transition (N ⇌ I ⇌ D) with an intermediate (I) state populated around 4.0 M urea concentration. The circular dichroism ([θ]222) and fluorescence emission spectra (λmax) of SphK1 with increasing concentrations of urea were analyzed to calculate Gibbs free energy (ΔG0) for both the transitions (N ⇌ I and I ⇌ D). A significant overlap of both the transitions obtained by two spectroscopic properties ([θ]222 and λmax) was observed, indicating that both N ⇌ I and I ⇌ D transition follow two-step equilibrium unfolding pattern. Also, we performed 100 ns molecular dynamics (MD) simulations to get atomistic insights into the structural changes in SphK1 with increasing urea concentrations. Our results showed a consistent pattern of the SphK1 unfolding with increasing urea concentrations. Together, spectroscopic and MD simulation findings provide deep insights into the unfolding mechanism and conformational features of SphK1.
Collapse
|
12
|
Qausain S, Khan FI, Lai D, Hassan MI, Basheeruddin M, Ahmed N, Khan MKA. Mechanistic insights into the urea-induced denaturation of a non-seleno thiol specific antioxidant human peroxiredoxin 6. Int J Biol Macromol 2020; 161:1171-1180. [PMID: 32485253 DOI: 10.1016/j.ijbiomac.2020.05.168] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 12/24/2022]
Abstract
Peroxiredoxin 6 (Prdx6) is a unique enzyme among mammalian peroxiredoxins as it lacks resolving cysteine. It is found to be involved in number of different diseases including tumours and its expression level is highest in lungs as compared to other organs. It has been found that Prdx6 plays a significant role different metabolic diseases, ocular damage, neurodegeneration and male infertility. It is a bifunctional protein having phospholipase A2 and peroxidase (also has the ability to reduce phospholipid hydroperoxides) activities. In order to complete the peroxidise reaction cycle it requires glutathione catalyzed by glutathione S-transferase. Equilibrium unfolding and conformational stability of Prdx6 was studied by using urea as a chemical denaturant to understand the changes it goes under cellular stress conditions. Three different spectroscopic methods were employed to monitor urea-induced denaturation. From the results obtained, it was found that the urea denaturation of Prdx6 follows a variable two state process due to non-coincidence of the normalized transition curves obtained from different optical probes. The different denaturation curves were normalized and thermodynamic parameters, ΔGDo, Gibbs free energy change related to the urea-induced denaturation, midpoint of denaturation (Cm), and m = (δΔGD / [urea]) were obtained. The structural information of Prdx6 were further analysed by several parameters obtained by 100 ns MD simulation. The results of MD simulation clearly favour the outcome of spectroscopic studies.
Collapse
Affiliation(s)
- Sana Qausain
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and Technology, GST Road, Vandalur, Chennai 600048, India
| | - Faez Iqbal Khan
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Dakun Lai
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Mohd Basheeruddin
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and Technology, GST Road, Vandalur, Chennai 600048, India
| | - Neesar Ahmed
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and Technology, GST Road, Vandalur, Chennai 600048, India
| | - Md Khurshid Alam Khan
- School of Life Sciences, B.S. Abdur Rahman Crescent Institute of Science and Technology, GST Road, Vandalur, Chennai 600048, India.
| |
Collapse
|