scholarly journals Characterization of an Atypical Trypanosoma brucei Hsp70 Demonstrates Its Cytosolic-Nuclear Localization and Modulation by Quercetin and Methylene Blue

2021 ◽  
Vol 22 (13) ◽  
pp. 6776
Author(s):  
Adélle Burger ◽  
Paula Macucule-Tinga ◽  
Stephen John Bentley ◽  
Michael Hans Ludewig ◽  
Ndumiso Nhlakanipho Mhlongo ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Atpase Activity ◽  
Trypanosoma Brucei ◽  
In Silico Analysis ◽  
Binding Pocket ◽  
Drug Candidates ◽  
Chaperone Function ◽  
Chaperone Binding ◽  
Silico Analysis

Trypanosoma brucei (Tb) harbours twelve Hsp70 chaperones. Of these, four are predicted to reside in the parasite cytosol. TbHsp70.c is predicted to be cytosolic and upregulated upon heat stress and is an ATPase that exhibits holdase chaperone function. Cytosol-localized Tbj2 stimulates the ATPase activity of TbHsp70.c. In the current study, immunofluorescence confirmed that TbHsp70.c is both a cytosolic and a nuclear protein. Furthermore, in silico analysis was used to elucidate an atypical linker and hydrophobic pocket. Tellingly, TbHsp70.c lacks the EEVD and GGMP motifs, both of which are implicated in substrate selectivity and co-chaperone binding in canonical Hsp70s. Far western analysis revealed that TbSTi1 interacts directly with TbHsp70 and TbHsp70.4, but does not bind TbHsp70.c. We further investigated the effect of quercetin and methylene blue on the Tbj2-driven ATPase activity of TbHsp70.c. We established that quercetin inhibited, whilst methylene blue enhanced, the Tbj2-stimulated ATPase activity of TbHsp70.c. Furthermore, these inhibitors were lethal to parasites. Lastly, we used molecular docking to show that quercetin and methylene blue may bind the nucleotide binding pocket of TbHsp70.c. Our findings suggest that small molecule inhibitors that target TbHsp70.c could be developed to serve as possible drug candidates against T. brucei.

scholarly journals Structure and Dynamics of an Archeal Monoglyceride Lipase from Palaeococcus ferrophilus as Revealed by Crystallography and In Silico Analysis

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 533
Author(s):  
Geoffray Labar ◽  
Nathalie Brandt ◽  
Amaury Flaba ◽  
Johan Wouters ◽  
Laurence Leherte
Keyword(s):  
Crystal Structure ◽  
In Silico Analysis ◽  
Binding Pocket ◽  
Structural Features ◽  
Crystallographic Analysis ◽  
Monoglyceride Lipase ◽  
Binding Pockets ◽  
Lid Domain ◽  
Silico Analysis

The crystallographic analysis of a lipase from Palaeococcus ferrophilus (PFL) previously annotated as a lysophospholipase revealed high structural conservation with other monoglyceride lipases, in particular in the lid domain and substrate binding pockets. In agreement with this observation, PFL was shown to be active on various monoacylglycerols. Molecular Dynamics (MD) studies performed in the absence and in the presence of ligands further allowed characterization of the dynamics of this system and led to a systematic closure of the lid compared to the crystal structure. However, the presence of ligands in the acyl-binding pocket stabilizes intermediate conformations compared to the crystal and totally closed structures. Several lid-stabilizing or closure elements were highlighted, i.e., hydrogen bonds between Ser117 and Ile204 or Asn142 and its facing amino acid lid residues, as well as Phe123. Thus, based on this complementary crystallographic and MD approach, we suggest that the crystal structure reported herein represents an open conformation, at least partially, of the PFL, which is likely stabilized by the ligand, and it brings to light several key structural features prone to participate in the closure of the lid.

In-Vitro and In-Silico Characterization of Xylose Reductase from Emericella nidulans

2019 ◽  
Vol 13 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Vishal Ahuja ◽  
Aashima Sharma ◽  
Ranju Kumari Rathour ◽  
Vaishali Sharma ◽  
Nidhi Rana ◽  
...  
Keyword(s):  
Production Process ◽  
In Silico ◽  
Xylose Reductase ◽  
In Silico Analysis ◽  
Emericella Nidulans ◽  
Higher Temperature ◽  
In Silico Characterization ◽  
Silico Analysis

Background: Lignocellulosic residues generated by various anthropogenic activities can be a potential raw material for many commercial products such as biofuels, organic acids and nutraceuticals including xylitol. Xylitol is a low-calorie nutritive sweetener for diabetic patients. Microbial production of xylitol can be helpful in overcoming the drawbacks of traditional chemical production process and lowring cost of production. Objective: Designing efficient production process needs the characterization of required enzyme/s. Hence current work was focused on in-vitro and in-silico characterization of xylose reductase from Emericella nidulans. Methods: Xylose reductase from one of the hyper-producer isolates, Emericella nidulans Xlt-11 was used for in-vitro characterization. For in-silico characterization, XR sequence (Accession No: Q5BGA7) was used. Results: Xylose reductase from various microorganisms has been studied but the quest for better enzymes, their stability at higher temperature and pH still continues. Xylose reductase from Emericella nidulans Xlt-11 was found NADH dependent and utilizes xylose as its sole substrate for xylitol production. In comparison to whole cells, enzyme exhibited higher enzyme activity at lower cofactor concentration and could tolerate higher substrate concentration. Thermal deactivation profile showed that whole cell catalysts were more stable than enzyme at higher temperature. In-silico analysis of XR sequence from Emericella nidulans (Accession No: Q5BGA7) suggested that the structure was dominated by random coiling. Enzyme sequences have conserved active site with net negative charge and PI value in acidic pH range. Conclusion: Current investigation supported the enzyme’s specific application i.e. bioconversion of xylose to xylitol due to its higher selectivity. In-silico analysis may provide significant structural and physiological information for modifications and improved stability.

In silico analysis of selenoprotein N (Gallus gallus): absence of EF-hand motif and the role of CUGS-helix domain in antioxidant protection

Metallomics ◽  
2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Shi-Yong Zhu ◽  
Li-Li Liu ◽  
Yue-Qiang Huang ◽  
Xiao-Wei Li ◽  
Milton Talukder ◽  
...  
Keyword(s):  
In Silico ◽  
Common Ancestor ◽  
In Silico Analysis ◽  
Antioxidant Protection ◽  
Jnk Pathway ◽  
Downstream Target ◽  
Ef Hand ◽  
Silico Analysis

Abstract Selenoprotein N (SEPN1) is critical to the normal muscular physiology. Mutation of SEPN1 can raise congenital muscular disorder in human. It is also central to maturation and structure of skeletal muscle in chicken. However, human SEPN1 contained an EF-hand motif, which was not found in chicken. And the biochemical and molecular characterization of chicken SEPN1 remains unclear. Hence, protein domains, transcription factors, and interactions of Ca2+ in SEPN1 were analyzed in silico to provide the divergence and homology between chicken and human in this work. The results showed that vertebrates’ SEPN1 evolved from a common ancestor. Human and chicken's SEPN1 shared a conserved CUGS-helix domain with function in antioxidant protection. SEPN1 might be a downstream target of JNK pathway, and it could respond to multiple stresses. Human's SEPN1 might not combine with Ca2+ with a single EF-hand motif in calcium homeostasis, and chicken SEPN1 did not have the EF-hand motif in the prediction, indicating the EF-hand motif malfunctioned in chicken SEPN1.

scholarly journals Characterization of the ATPase activity of topoisomerase II from Leishmania donovani and identification of residues conferring resistance to etoposide

2005 ◽  
Vol 390 (2) ◽  
pp. 419-426 ◽  
Author(s):  
Tanushri Sengupta ◽  
Mandira Mukherjee ◽  
Aditi Das ◽  
Chhabinath Mandal ◽  
Rakhee Das ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Topoisomerase Ii ◽  
Leishmania Donovani ◽  
Binding Pocket ◽  
Dna Topoisomerase ◽  
Terminal Domain ◽  
Specific Selectivity ◽  
Eukaryotic Dna ◽  
First Time

We have cloned and expressed the 43 kDa N-terminal domain of Leishmania donovani topoisomerase II. This protein has an intrinsic ATPase activity and obeys Michaelis–Menten kinetics. Cross-linking studies indicate that the N-terminal domain exists as a dimer both in the presence and absence of nucleotides. Etoposide, an effective antitumour drug, traps eukaryotic DNA topoisomerase II in a covalent complex with DNA. In the present study, we report for the first time that etoposide inhibits the ATPase activity of the recombinant N-terminal domain of L. donovani topoisomerase II. We have modelled the structure of this 43 kDa protein and performed molecular docking analysis with the drug. Mutagenesis of critical amino acids in the vicinity of the ligand-binding pocket reveals less efficient inhibition of the ATPase activity of the enzyme by etoposide. Taken together, these results provide an insight for the development of newer therapeutic agents with specific selectivity.

scholarly journals A persistently replicating SARS-CoV-2 variant derived from an asymptomatic individual

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Francesca Caccuri ◽  
Alberto Zani ◽  
Serena Messali ◽  
Marta Giovanetti ◽  
Antonella Bugatti ◽  
...  
Keyword(s):  
Viral Load ◽  
Selection Process ◽  
In Silico Analysis ◽  
High Viral Load ◽  
Current Approach ◽  
The One ◽  
Host Evolution ◽  
Silico Analysis ◽  
Generation Sequencing

Abstract Background Since the first outbreak of SARS-CoV-2, the clinical characteristics of the Coronavirus Disease 2019 (COVID-19) have been progressively changed. Data reporting a viral intra-host and inter-host evolution favouring the appearance of mild SARS-CoV-2 strains are since being accumulating. To better understand the evolution of SARS-CoV-2 pathogenicity and its adaptation to the host, it is therefore crucial to investigate the genetic and phenotypic characteristics of SARS-CoV-2 strains circulating lately in the epidemic. Methods Nasopharyngeal swabs have been analyzed for viral load in the early (March 2020) and late (May 2020) phases of epidemic in Brescia, Italy. Isolation of SARS-CoV-2 from 2 high viral load specimens identified on March 9 (AP66) and on May 8 (GZ69) was performed on Vero E6 cells. Amount of virus released was assessed by quantitative PCR. Genotypic characterization of AP66 and GZ69 was performed by next generation sequencing followed by an in-depth in silico analysis of nucleotide mutations. Results The SARS-CoV-2 GZ69 strain, isolated in May from an asymptomatic healthcare worker, showed an unprecedented capability of replication in Vero E6 cells in the absence of any evident cytopathic effect. Vero E6 subculturing, up to passage 4, showed that SARS-CoV-2 GZ69 infection was as productive as the one sustained by the cytopathic strain AP66. Whole genome sequencing of the persistently replicating SARS-CoV-2 GZ69 has shown that this strain differs from the early AP66 variant in 9 nucleotide positions (C2939T; C3828T; G21784T; T21846C; T24631C; G28881A; G28882A; G28883C; G29810T) which lead to 6 non-synonymous substitutions spanning on ORF1ab (P892S; S1188L), S (K74N; I95T) and N (R203K, G204R) proteins. Conclusions Identification of the peculiar SARS-CoV-2 GZ69 strain in the late Italian epidemic highlights the need to better characterize viral variants circulating among asymptomatic or paucisymptomatic individuals. The current approach could unravel the ways for future studies aimed at analyzing the selection process which favours viral mutations in the human host.

scholarly journals Cloning and characterization of novel human SLC4A8 gene products encoding Na+-driven Cl−/HCO3− exchanger variants NDCBE-A, -C, and -D

2008 ◽  
Vol 34 (3) ◽  
pp. 265-276 ◽  
Author(s):  
Mark D. Parker ◽  
Patrice Bouyer ◽  
Christopher M. Daly ◽  
Walter F. Boron
Keyword(s):  
In Silico Analysis ◽  
Functional Expression ◽  
Inhibitory Effect ◽  
Functional Difference ◽  
The Novel ◽  
Equivalent Position ◽  
Rapid Amplification ◽  
Novel Exon ◽  
Silico Analysis

The reported sequences of the human and mouse Na+-driven Cl−/HCO3− exchangers (NDCBEs) differ greatly in their extreme cytosolic COOH termini (Ct). In human NDCBE (NDCBE-B), a 17-amino acid (aa) sequence replaces 66 aa at the equivalent position in mouse NDCBE (NDCBE-A). We performed 5′- and 3′-rapid amplification of cDNA ends (RACE) on human brain cDNA, followed by PCR of full-length cDNAs to determine whether the human SLC4A8 gene was capable of producing the mouselike Ct sequence. Our study confirmed the presence in human cDNA of mouse NDCBE-like transcripts (human NDCBE-A) and also disclosed the existence of three further novel NDCBE transcripts that we have called NDCBE-C, NDCBE-D, and NDCBE-D′. The novel NDCBE-C/D/D′ transcripts initiate at a novel “exon 0” positioned ∼35 kb upstream of the first exon of NDCBE-A/B. NDCBE-C/D/D′ protein products are predicted to be truncated by 54 aa in the cytosolic NH2 terminus (Nt) compared with NDCBE-A/B. Our data, combined with a new in silico analysis of partial transcripts reported by others in the region of the human SLC4A8 gene, increase the known extent of the SLC4A8 gene by 49 kb, to 124 kb. A functional comparison of NDCBE-A/B/C/D expressed in Xenopus oocytes demonstrates that the Nt variation does not affect the basal functional expression of NDCBE, but those with the shorter Ct have a 25–50% reduced functional expression compared with those with the longer Ct. By comparison with an artificially truncated NDCBE that contains neither 17-aa nor 66-aa Ct cassette, we determined that the functional difference is unrelated to the 66-aa cassette of NDCBE-A/C, but is instead due to an inhibitory effect of the 17-aa cassette of NDCBE-B/D.

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