Functional characterization and molecular modelling of FnFgBP, a surface protein from Streptococcus agalactiae

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91824-91835 ◽  
Author(s):  
Shobana Ponnuvel ◽  
Dhanalakshmi Bandaru ◽  
Preethi Ragunathan ◽  
Karthe Ponnuraj
Keyword(s):  
Molecular Modeling ◽  
Ligand Binding ◽  
Molecular Modelling ◽  
Streptococcus Agalactiae ◽  
Functional Characterization ◽  
Surface Protein ◽  
Binding Property ◽  
Binding Mechanism ◽  
Fibrinogen Binding

GBS1263 (FnFgBP) exhibits dual-ligand (fibronectin and fibrinogen) binding property. Molecular modeling of FnFgBP is suggestive of a unique ligand binding mechanism.

scholarly journals Rga is a regulator of adherence and pilus formation in Streptococcus agalactiae

Microbiology ◽  
2011 ◽  
Vol 157 (8) ◽  
pp. 2319-2327 ◽  
Author(s):  
Ulrike Samen ◽  
Beate Heinz ◽  
Heike Boisvert ◽  
Bernhard J. Eikmanns ◽  
Dieter J. Reinscheid ◽  
...  
Keyword(s):  
Streptococcus Agalactiae ◽  
Functional Characterization ◽  
A549 Cells ◽  
Surface Glycoprotein ◽  
Promoter Regions ◽  
Mobility Shift ◽  
Significant Similarity ◽  
Human Fibrinogen ◽  
Fibrinogen Binding ◽  
Mutant Phenotypes

Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in neonates and is also the causative agent of several serious infections in immunocompromised adults. S. agalactiae encounters multiple niches during an infection, suggesting that regulatory mechanisms control the expression of specific virulence factors in this bacterium. The present study describes the functional characterization of a gene from S. agalactiae, designated rga, which encodes a protein with significant similarity to members of the RofA-like protein (RALP) family of transcriptional regulators. After deletion of the rga gene in the genome of S. agalactiae, the mutant strain exhibited significantly reduced expression of the genes srr-1 and pilA, which encode a serine-rich repeat surface glycoprotein and a pilus protein, respectively, and moderately increased expression of the fbsA gene, which encodes a fibrinogen-binding protein. Electrophoretic mobility shift assays demonstrated specific DNA binding of purified Rga to the promoter regions of pilA and fbsA, suggesting that Rga directly controls pilA and fbsA. Adherence assays revealed significantly reduced binding of the Δrga mutant to epithelial HEp-2 cells and to immobilized human keratin 4, respectively. In contrast, the adherence of the Δrga mutant to A549 cells and its binding to human fibrinogen was significantly increased. Immunoblot and immunoelectron microscopy revealed that the quantity of pilus structures was significantly reduced in the Δrga mutant compared with the parental strain. The wild-type phenotype could be restored by plasmid-mediated expression of rga, demonstrating that the mutant phenotypes resulted from a loss of Rga function.

scholarly journals Putative ligand binding sites of two functionally characterized bark beetle odorant receptors

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Jothi K. Yuvaraj ◽  
Rebecca E. Roberts ◽  
Yonathan Sonntag ◽  
Xiao-Qing Hou ◽  
Ewald Grosse-Wilde ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Bark Beetle ◽  
Pest Control ◽  
Binding Sites ◽  
Functional Characterization ◽  
Site Directed Mutagenesis ◽  
Odorant Receptors ◽  
Functional Evolution ◽  
General Importance ◽  
Insight Into

Abstract Background Bark beetles are major pests of conifer forests, and their behavior is primarily mediated via olfaction. Targeting the odorant receptors (ORs) may thus provide avenues towards improved pest control. Such an approach requires information on the function of ORs and their interactions with ligands, which is also essential for understanding the functional evolution of these receptors. Hence, we aimed to identify a high-quality complement of ORs from the destructive spruce bark beetle Ips typographus (Coleoptera, Curculionidae, Scolytinae) and analyze their antennal expression and phylogenetic relationships with ORs from other beetles. Using 68 biologically relevant test compounds, we next aimed to functionally characterize ecologically important ORs, using two systems for heterologous expression. Our final aim was to gain insight into the ligand-OR interaction of the functionally characterized ORs, using a combination of computational and experimental methods. Results We annotated 73 ORs from an antennal transcriptome of I. typographus and report the functional characterization of two ORs (ItypOR46 and ItypOR49), which are responsive to single enantiomers of the common bark beetle pheromone compounds ipsenol and ipsdienol, respectively. Their responses and antennal expression correlate with the specificities, localizations, and/or abundances of olfactory sensory neurons detecting these enantiomers. We use homology modeling and molecular docking to predict their binding sites. Our models reveal a likely binding cleft lined with residues that previously have been shown to affect the responses of insect ORs. Within this cleft, the active ligands are predicted to specifically interact with residues Tyr84 and Thr205 in ItypOR46. The suggested importance of these residues in the activation by ipsenol is experimentally supported through site-directed mutagenesis and functional testing, and hydrogen bonding appears key in pheromone binding. Conclusions The emerging insight into ligand binding in the two characterized ItypORs has a general importance for our understanding of the molecular and functional evolution of the insect OR gene family. Due to the ecological importance of the characterized receptors and widespread use of ipsenol and ipsdienol in bark beetle chemical communication, these ORs should be evaluated for their potential use in pest control and biosensors to detect bark beetle infestations.

scholarly journals Cryptic-site binding mechanism of medium-sized Bcl-xL inhibiting compounds elucidated by McMD-based dynamic docking simulations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gert-Jan Bekker ◽  
Ikuo Fukuda ◽  
Junichi Higo ◽  
Yoshifumi Fukunishi ◽  
Narutoshi Kamiya
Keyword(s):  
Ligand Binding ◽  
Cancer Progression ◽  
Hydrophobic Interactions ◽  
Binding Mechanism ◽  
Docking Simulations ◽  
Large Conformational Change ◽  
Binding Pockets ◽  
Dynamic Docking ◽  
Site Binding ◽  
Apo State

AbstractWe have performed multicanonical molecular dynamics (McMD) based dynamic docking simulations to study and compare the binding mechanism between two medium-sized inhibitors (ABT-737 and WEHI-539) that bind to the cryptic site of Bcl-xL, by exhaustively sampling the conformational and configurational space. Cryptic sites are binding pockets that are transiently formed in the apo state or are induced upon ligand binding. Bcl-xL, a pro-survival protein involved in cancer progression, is known to have a cryptic site, whereby the shape of the pocket depends on which ligand is bound to it. Starting from the apo-structure, we have performed two independent McMD-based dynamic docking simulations for each ligand, and were able to obtain near-native complex structures in both cases. In addition, we have also studied their interactions along their respective binding pathways by using path sampling simulations, which showed that the ligands form stable binding configurations via predominantly hydrophobic interactions. Although the protein started from the apo state, both ligands modulated the pocket in different ways, shifting the conformational preference of the sub-pockets of Bcl-xL. We demonstrate that McMD-based dynamic docking is a powerful tool that can be effectively used to study binding mechanisms involving a cryptic site, where ligand binding requires a large conformational change in the protein to occur.

Recreational drugs 25I-NBOH and 25I-NBOMe bind to both Sudlow's sites I and II of Human Serum Albumin (HSA): Biophysical and molecular modeling studies

2021 ◽  
Author(s):  
Wellington Alves de Barros ◽  
Marina de Magalhães Silva ◽  
Maria Dayanne de Araújo Dantas ◽  
Josue Santos ◽  
Isis Figueiredo ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Molecular Modelling ◽  
Recreational Drugs ◽  
Modeling Studies ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
Molecular Modeling Studies

Experimental, biophysical, and molecular modelling studies between 25I-NBOH and 25I-NBOMe with human serum albumin (HSA) have indicated that these recreational drugs simultaneously bind to site I and II of the...

scholarly journals Ligand binding mechanism of β-lactoglobulin

1999 ◽  
Vol 39 (supplement) ◽  
pp. S118
Author(s):  
M. Taguchi ◽  
M Hoshino ◽  
S. Aimoto ◽  
Y. Goto
Keyword(s):  
Ligand Binding ◽  
Binding Mechanism ◽  
Β Lactoglobulin

scholarly journals Combinatorial peptide libraries reveal the ligand-binding mechanism of the oligopeptide receptor OppA of Lactococcus lactis

2000 ◽  
Vol 97 (23) ◽  
pp. 12487-12492 ◽  
Author(s):  
F. J. M. Detmers ◽  
F. C. Lanfermeijer ◽  
R. Abele ◽  
R. W. Jack ◽  
R. Tampe ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Lactococcus Lactis ◽  
Peptide Libraries ◽  
Binding Mechanism ◽  
Combinatorial Peptide Libraries
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