scholarly journals Biophysical and structural studies reveal marginal stability of Acyl ACP Reductase: a crucial hydrocarbon biosynthetic enzyme

2020 ◽  
Author(s):  
Ashima Sharma ◽  
Tabinda Shakeel ◽  
Mayank Gupta ◽  
Girish Rajacharya ◽  
Syed Shams Yazdani
Keyword(s):  
Gel Filtration ◽  
Standard Free Energy ◽  
Biofuel Production ◽  
Dynamics Simulation ◽  
Marginal Stability ◽  
Structural Stabilization ◽  
E Coli ◽  
Metal Affinity ◽  
Single Mass ◽  
Protein Molecular Dynamics

Abstract Background: Acyl-ACP reductase (AAR) is one of the two key cyanobacterial enzymes along with aldehyde deformylating oxygenase (ADO) involved in synthesis of long-chain alkanes, a drop-in biofuel. The enzyme is prone to aggregation when expressed in E. coli, leading to varying alkane levels. Intriguingly, the structural characterization remains largely elusive as AAR alone failed to form stable crystals, possibly due to a number of intrinsically flexible random regions. The present work attempts to fill a gap in the literature by investigating the crucial structural aspects of AAR protein associated with its stability and folding. Results: The AAR protein was recombinant expressed in E. coli and purified by metal affinity and gel filtration chromatography. Characterization by dynamic light scattering experiment revealed that recombinantly expressed AAR in E. coli existed in multiple-sized protein particles in the range of 36.4 to 51.6 nm. Intact mass spectrometry revealed that recombinant AAR was heterogenous due to diverse lipidation and de-lipidation resulted in a single mass peak of 40296.87 Da as predicted. Interestingly, while thermal- and urea-based denaturation of AAR showed 2-state unfolding transition in circular dichroism and intrinsic fluorescent spectroscopy, the unfolding process of AAR was a 3-state pathway in GdnHCl solution. Lower concentration of GdnHCl appeared to be stabilizing the protein, suggesting that the protein milieu plays a significant role in dictating it’s folding. Standard free energy (∆GH2ONU) of ~4.5 kcal/mol for steady-state unfolding of AAR indicated borderline stability of the protein. Molecular dynamics simulation conducted on AAR structure in presence of KCl, an ionic solvent with similar properties as GdnHCl at lower concentrations, suggested that KCl mediates structural stabilization especially at the concentration of 375 mM, and thus was responsible for enhancing its activity. KCl presence also resulted in regional alteration towards the binding site of its neighbouring pathway enzyme, ADO, thus paving the way for coordinated catalysis.Conclusion: Based on these evidences, we propose that the marginal stability of AAR are plausible contributing reasons for aggregation propensity and hence low catalytic activity of the enzyme when expressed in E. coli for biofuel production. Our results show path for building superior biocatalyst for higher biofuel production.

scholarly journals Biophysical and structural studies reveal marginal stability of a crucial hydrocarbon biosynthetic enzyme acyl ACP reductase

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ashima Sharma ◽  
Tabinda Shakeel ◽  
Mayank Gupta ◽  
Girish H. Rajacharya ◽  
Syed Shams Yazdani
Keyword(s):  
Standard Free Energy ◽  
Biofuel Production ◽  
Marginal Stability ◽  
Structural Studies ◽  
E Coli ◽  
Aggregation Propensity ◽  
Scattering Experiment ◽  
Intact Mass ◽  
Protein Particles ◽  
Structural Aspects

AbstractAcyl-ACP reductase (AAR) is one of the two key cyanobacterial enzymes along with aldehyde deformylating oxygenase (ADO) involved in the synthesis of long-chain alkanes, a drop-in biofuel. The enzyme is prone to aggregation when expressed in Escherichia coli, leading to varying alkane levels. The present work attempts to investigate the crucial structural aspects of AAR protein associated with its stability and folding. Characterization by dynamic light scattering experiment and intact mass spectrometry revealed that recombinantly expressed AAR in E. coli existed in multiple-sized protein particles due to diverse lipidation. Interestingly, while thermal- and urea-based denaturation of AAR showed 2-state unfolding transition in circular dichroism and intrinsic fluorescent spectroscopy, the unfolding process of AAR was a 3-state pathway in GdnHCl solution suggesting that the protein milieu plays a significant role in dictating its folding. Apparent standard free energy $$\left( {\Delta {\text{G}}_{{{\text{NU}}}}^{{{\text{H}}_{2} {\text{O}}}} } \right)$$ Δ G NU H 2 O of ~ 4.5 kcal/mol for the steady-state unfolding of AAR indicated borderline stability of the protein. Based on these evidences, we propose that the marginal stability of AAR are plausible contributing reasons for aggregation propensity and hence the low catalytic activity of the enzyme when expressed in E. coli for biofuel production. Our results show a path for building superior biocatalyst for higher biofuel production.

Deleting two C-terminal α-helices is effective to crystallize the bacterial ABC transporterEscherichia coliMsbA complexed with AMP-PNP

2010 ◽  
Vol 66 (3) ◽  
pp. 319-323 ◽  
Author(s):  
Kanako Terakado ◽  
Atsushi Kodan ◽  
Hiroaki Nakano ◽  
Yasuhisa Kimura ◽  
Kazumitsu Ueda ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Binding Affinity ◽  
Deletion Mutant ◽  
Gel Filtration ◽  
Wild Type ◽  
Gel Filtration Chromatography ◽  
E Coli ◽  
Metal Affinity

An MsbA deletion mutant ΔC21 that lacks the two C-terminal α-helices was expressed inEscherichia colistrain C41 and purified by metal-affinity and gel-filtration chromatography. Purified ΔC21 retained 26% of the activity of the wild-type ATPase and had a similar binding affinity to fluorescent nucleotide derivatives. Although crystals of wild-type MsbA complexed with adenosine 5′-(β,γ-imido)triphosphate could not be obtained, crystals of ΔC21 that diffracted to 4.5 Å resolution were obtained. The preliminary ΔC21 structure had the outward-facing conformation, in contrast to the previously reportedE. coliMsbA structure. This result suggests that deletion of the C-terminal α-helices may play a role in facilitating the outward-facing nucleotide-bound crystal structure of EcMsbA.

Production and Preliminary In Vivo Evaluations of a Novel in silico-designed L2-based Potential HPV Vaccine

2020 ◽  
Vol 21 (4) ◽  
pp. 316-324
Author(s):  
Manica Negahdaripour ◽  
Navid Nezafat ◽  
Reza Heidari ◽  
Nasrollah Erfani ◽  
Nasim Hajighahramani ◽  
...  
Keyword(s):  
In Silico ◽  
Group Versus ◽  
Tlr Agonists ◽  
E Coli ◽  
Metal Affinity ◽  
Th1 And Th2 Cytokines ◽  
Ifn Γ ◽  
Humoral Responses ◽  
Future Work

Background: L2-based Human Papillomavirus (HPV) prophylactic vaccines, containing epitopes from HPV minor capsid proteins, are under investigation as second-generation HPV vaccines. No such vaccine has passed clinical trials yet, mainly due to the low immunogenicity of peptide vaccines; so efforts are being continued. A candidate vaccine composed of two HPV16 L2 epitopes, flagellin and a Toll-Like Receptor (TLR) 4 agonist (RS09) as adjuvants, and two universal T-helper epitopes was designed in silico in our previous researches. Methods: The designed vaccine construct was expressed in E. coli BL21 (DE3) and purified through metal affinity chromatography. Following mice vaccination, blood samples underwent ELISA and flow cytometry analyses for the detection of IgG and seven Th1 and Th2 cytokines. Results: Following immunization, Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-5, IL-10) type cytokines, as well as IgG, were induced significantly compared with the PBS group. Significant increases in IFN-γ, IL-2, and IL-5 levels were observed in the vaccinated group versus Freund’s adjuvant group. Conclusion: The obtained cytokine induction profile implied both cellular and humoral responses, with a more Th-1 favored trend. However, an analysis of specific antibodies against L2 is required to confirm humoral responses. No significant elevation in inflammatory cytokines, (IL-6 and TNF-α), suggested a lack of unwanted inflammatory side effects despite using a combination of two TLR agonists. The designed construct might be capable of inducing adaptive and innate immunity; nevertheless, comprehensive immune tests were not conducted at this stage and will be a matter of future work.

scholarly journals Biosynthesis of the Cyanobacterial Light-Harvesting Polypeptide Phycoerythrocyanin Holo-α Subunit in a Heterologous Host

2002 ◽  
Vol 184 (17) ◽  
pp. 4666-4671 ◽  
Author(s):  
Aaron J. Tooley ◽  
Alexander N. Glazer
Keyword(s):  
Ternary Complexes ◽  
Covalent Attachment ◽  
Heme Oxygenase 1 ◽  
Α Subunit ◽  
Ionization Time ◽  
E Coli ◽  
Metal Affinity ◽  
Flight Mass Spectrometry ◽  
Genes Encoding ◽  
Cyanobacterial Genes

ABSTRACT The entire pathway for the biosynthesis of the phycobiliviolin-bearing His-tagged holo-α subunit of the cyanobacterial photosynthetic accessory protein phycoerythrocyanin was reconstituted in Escherichia coli. Cyanobacterial genes encoding enzymes required for the conversion of heme to 3Z-phycocyanobilin, a precursor of phycobiliviolin (namely, heme oxygenase 1 and 3Z-phycocyanobilin:ferredoxin oxidoreductase), were expressed from a plasmid under the control of the hybrid trp-lac (trc) promoter. Genes for the apo-phycoerythrocyanin α subunit (pecA) and the heterodimeric lyase/isomerase (pecE and pecF), which catalyzes both the covalent attachment of phycocyanobilin and its concurrent isomerization to phycobiliviolin, were expressed from the trc promoter on a second plasmid. Upon induction, recombinant E. coli used endogenous heme to produce holo-PecA with absorbance and fluorescence properties similar to those of the same protein produced in cyanobacteria. About two-thirds of the apo-PecA was converted to holo-PecA. No significant bilin addition took place in a similarly engineered E. coli strain that lacks pecE and pecF. By using immobilized metal affinity chromatography, both apo-PecA and holo-PecA were isolated as ternary complexes with PecE and PecF. The identities of all three components in the ternary complexes were established unambiguously by protein and tryptic peptide analyses performed by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

scholarly journals On-column Refolding of an Insoluble His6-tagged Recombinant EC-SOD Overexpressed in Escherichia coli

2005 ◽  
Vol 37 (4) ◽  
pp. 265-269 ◽  
Author(s):  
Xi-Qiang Zhu ◽  
Su-Xia Li ◽  
Hua-Jun He ◽  
Qin-Sheng Yuan
Keyword(s):  
Escherichia Coli ◽  
Inclusion Bodies ◽  
Mass Ratio ◽  
Chain Reaction ◽  
Expression Plasmid ◽  
Protein Subunits ◽  
E Coli ◽  
Metal Affinity ◽  
Polymerase Chain ◽  
Escherichia Coli Expression

Abstract The EC-SOD cDNA was cloned by polymerase chain reaction (PCR) and inserted into the Escherichia coli expression plasmid pET-28a(+) and transformed into E. coli BL21(DE3). The corresponding protein that was overexpressed as a recombinant His6-tagged EC-SOD was present in the form of inactive inclusion bodies. This structure was first solubilized under denaturant conditions (8.0 M urea). Then, after a capture step using immobilized metal affinity chromatography (IMAC), a gradual refolding of the protein was performed on-column using a linear urea gradient from 8.0 M to 1.5 M in the presence of glutathione (GSH) and oxidized glutathione (GSSG). The mass ratio of GSH to GSSG was 4:1. The purified enzyme was active, showing that at least part of the protein was properly refolded. The protein was made concentrated by ultrafiltration, and then isolated using Sephacryl S-200 HR. There were two protein peaks in the A280 profile. Based on the results of electrophoresis, we concluded that the two fractions were formed by protein subunits of the same mass, and in the fraction where the molecular weight was higher, the dimer was formed through the disulfide bond between subunits. Activities were detected in the two fractions, but the activity of the dimer was much higher than that of the single monomer. The special activities of the two fractions were found to be 3475 U/mg protein and 510 U/mg protein, respectively.

P. vortex-mediated strategies for polysaccharides decomposition

TECHNOLOGY ◽  
2015 ◽  
Vol 03 (02n03) ◽  
pp. 80-83
Author(s):  
Mark Polikovsky ◽  
Eshel Ben-Jacob ◽  
Alin Finkelshtein
Keyword(s):  
Degradation Products ◽  
Cellulose Degradation ◽  
Cellulose Hydrolysis ◽  
Industrial Applications ◽  
Biofuel Production ◽  
E Coli ◽  
Novel Approach ◽  
Textile Manufacture ◽  
Hydrolysis Of Cellulose ◽  
The Relationship

Cellulose hydrolysis has many industrial applications such as biofuel production, food, paper and textile manufacture. Here, we present a novel approach to cellulose hydrolysis using a consortium of motile bacteria, Paenibacillus vortex, that can swarm on solid medium carrying a non-motile recombinant E. coli cargo strain expressing the β-glucosidase and cellulase genes that facilitate the hydrolysis of cellulose. These two species cooperate; the relationship is mutually beneficial: the E. coli is dispersed over long distances, while the P. vortex bacteria gain from the supply of cellulose degradation products. This enables the use of such consortia in this area of biotechnology.

scholarly journals Crystallization and preliminary X-ray diffraction analysis of UspE fromEscherichia coli

2014 ◽  
Vol 70 (12) ◽  
pp. 1640-1642 ◽  
Author(s):  
Yongbin Xu ◽  
Chun-Shan Quan ◽  
Xuanzhen Jin ◽  
Xiaoling Jin ◽  
Jing Zhao ◽  
...  
Keyword(s):  
Stress Proteins ◽  
Gel Filtration ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Data Set ◽  
X Ray ◽  
Cell Parameters ◽  
E Coli ◽  
Vapour Diffusion ◽  
Induced Genes

Universal stress proteins (Usps) are among the most highly induced genes when bacteria are subjected to several stress conditions such as heat shock, nutrient starvation or the presence of oxidants or other stress agents.Escherichia colihas five small Usps and one tandem-type Usp. UspE (or YdaA) is the tandem-type Usp and consists of two Usp domains arranged in tandem. To date, the structure of UspE remains to be elucidated. To contribute to the molecular understanding of the function of the tandem-type UspE, UspE fromE. coliwas overexpressed and the recombinant protein was purified using Ni–NTA affinity, Q anion-exchange and gel-filtration chromatography. Crystals of UspE were obtained by sitting-drop vapour diffusion. A diffraction data set was collected to a resolution of 3.2 Å from flash-cooled crystals. The crystals belonged to the tetragonal space groupI4122 orI4322, with unit-cell parametersa=b= 121.1,c = 241.7 Å.

scholarly journals Finding Pathogenic nsSNP’s and their structural effect on COPS2 using Molecular Dynamic Approach

2020 ◽  
Author(s):  
Ashish Malik ◽  
Kajal Pande ◽  
Abhishek Kumar ◽  
Alekhya Vemula ◽  
R Madhuri ◽  
...  
Keyword(s):  
Neuronal Differentiation ◽  
Developmental Process ◽  
Normal Activity ◽  
Structural Effect ◽  
Dynamics Simulation ◽  
Cop9 Signalosome ◽  
Nucleotide Polymorphisms ◽  
Discovery Studio ◽  
Essential Components ◽  
Protein Molecular Dynamics

AbstractCOP9 Signalosome Subunit 2 is a highly conserved multiprotein complex which is involved in the cellular process and developmental process. It is one of the essential components in the COP9 Signalosome Complex (CSN). It is also involved in neuronal differentiation interacting with NIF3L1. The gene involved in neuronal differentiation is negatively regulated due to the transcription co-repressor interaction of NIF3L1 with COPS2. In the present study, we have evaluated the outcome for 90 non-synonymous single nucleotide polymorphisms (nsSNP’s) in COPS2 gene through computational tools. After the analysis, 4 SNP’s (S120C, N144S, Y159H, R173C) were found to be deleterious. The native and mutated structures were prepared using discovery studio and docked to check the interactions with NIF3L1.On the basis of ZDOCK score the top 3 mutations (N144S, Y159H, R173C) were screened out. Further to analyze the effect of amino acid substitution on the molecular structure of protein Molecular Dynamics simulation was carried out. Analysis based on RMSD, RMSF, RG, H-bond showed a significant deviation in the graph, which demonstrated conformation change and instability compared to the wild structure. As it is known mutations in COPS2 gene can disrupt the normal activity of the CSN2 protein which may cause neuronal differentiation. Our results showed N144S, Y159H and R173C mutations are to be more pathogenic and may cause disease

scholarly journals NMR structure of the C-terminal domain of TonB protein from Pseudomonas aeruginosa

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5412 ◽  
Author(s):  
Jesper S. Oeemig ◽  
O.H. Samuli Ollila ◽  
Hideo Iwaï
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Structural Changes ◽  
Nmr Structure ◽  
Dynamics Simulation ◽  
Solution Nmr ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Terminal Domain ◽  
Tonb Protein ◽  
Monomeric Structure

The TonB protein plays an essential role in the energy transduction system to drive active transport across the outer membrane (OM) using the proton-motive force of the cytoplasmic membrane of Gram-negative bacteria. The C-terminal domain (CTD) of TonB protein is known to interact with the conserved TonB box motif of TonB-dependent OM transporters, which likely induces structural changes in the OM transporters. Several distinct conformations of differently dissected CTDs of Escherichia coli TonB have been previously reported. Here we determined the solution NMR structure of a 96-residue fragment of Pseudomonas aeruginosa TonB (PaTonB-96). The structure shows a monomeric structure with the flexible C-terminal region (residues 338–342), different from the NMR structure of E. coli TonB (EcTonB-137). The extended and flexible C-terminal residues are confirmed by 15N relaxation analysis and molecular dynamics simulation. We created models for the PaTonB-96/TonB box interaction and propose that the internal fluctuations of PaTonB-96 makes it more accessible for the interactions with the TonB box and possibly plays a role in disrupting the plug domain of the TonB-dependent OM transporters.

Sign in / Sign up

Export Citation Format

Share Document