scholarly journals Structures of the Plasmodium falciparum heat-shock protein 70-x ATPase domain in complex with chemical fragments identify conserved and unique binding sites

2021 ◽  
Vol 77 (8) ◽  
Author(s):  
Nada Mohamad ◽  
Ailsa O'Donoghue ◽  
Anastassia L. Kantsadi ◽  
Ioannis Vakonakis
Keyword(s):  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Binding Sites ◽  
Binding Pocket ◽  
Atpase Domain ◽  
Binding Domains ◽  
Small Molecule Ligands ◽  
Ligand Interactions ◽  
Crystallographic Structures ◽  
Febrile Episodes

Plasmodium falciparum invades erythrocytes and extensively modifies them in a manner that increases the virulence of this malaria parasite. A single heat-shock 70 kDa-type chaperone, PfHsp70-x, is among the parasite proteins exported to the host cell. PfHsp70-x assists in the formation of a key protein complex that underpins parasite virulence and supports parasite growth during febrile episodes. Previous work resolved the crystallographic structures of the PfHsp70-x ATPase and substrate-binding domains, and showed them to be highly similar to those of their human counterparts. Here, 233 chemical fragments were screened for binding to the PfHsp70-x ATPase domain, resulting in three crystallographic structures of this domain in complex with ligands. Two binding sites were identified, with most ligands binding proximal to the ATPase nucleotide-binding pocket. Although amino acids participating in direct ligand interactions are conserved between the parasite and human erythrocytic chaperones, one nonconserved residue is also present near the ligand. This work suggests that PfHsp70-x features binding sites that may be exploitable by small-molecule ligands towards the specific inhibition of the parasite chaperone.

scholarly journals Antimalarial activity of tetrahydro-β-carbolines targeting the ATP binding pocket of the Plasmodium falciparum heat shock 90 protein

2020 ◽  
Vol 30 (21) ◽  
pp. 127502
Author(s):  
Scott Eagon ◽  
Jared T. Hammill ◽  
Jordan Bach ◽  
Nikalet Everson ◽  
Tyler A. Sisley ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Antimalarial Activity ◽  
Binding Pocket ◽  
Atp Binding

scholarly journals Structure of the substrate-binding domain of Plasmodium falciparum heat-shock protein 70-x

2020 ◽  
Vol 76 (10) ◽  
pp. 495-500
Author(s):  
Julia Schmidt ◽  
Ioannis Vakonakis
Keyword(s):  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Malaria Parasite ◽  
Substrate Binding ◽  
Binding Domain ◽  
Crystallographic Structure ◽  
Hydrophobic Peptide ◽  
Febrile Episodes ◽  
Substrate Binding Domain ◽  
Human Hsp70

The malaria parasite Plasmodium falciparum extensively modifies erythrocytes that it invades by exporting a large complement of proteins to the host cell. Among these exported components is a single heat-shock 70 kDa class protein, PfHsp70-x, that supports the virulence and growth rate of the parasite during febrile episodes. The ATP-binding domain of PfHsp70-x has previously been resolved and showed the presence of potentially druggable epitopes that differ from those on human Hsp70 chaperones. Here, the crystallographic structure of the substrate-binding domain (SBD) of PfHsp70-x is presented in complex with a hydrophobic peptide. The PfHsp70-x SBD is shown to be highly similar to the counterpart from a human erythrocytic Hsp70 chaperone. The binding of substrate at the interface between β-sandwich and α-helical subdomains of this chaperone segment is also conserved between the malaria parasite and humans. It is hypothesized that the parasite may partly exploit human chaperones for intra-erythrocytic trafficking and maintenance of its exported proteome.

Unprecedented conformational flexibility revealed in the ligand-binding domains of theBovicola ovisecdysone receptor (EcR) and ultraspiracle (USP) subunits

2014 ◽  
Vol 70 (7) ◽  
pp. 1954-1964 ◽  
Author(s):  
Bin Ren ◽  
Thomas S. Peat ◽  
Victor A. Streltsov ◽  
Matthew Pollard ◽  
Ross Fernley ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Binding Pocket ◽  
Conformational Flexibility ◽  
Order Structure ◽  
Ecdysone Receptor ◽  
Binding Region ◽  
X Ray ◽  
Receptor Structure ◽  
Binding Domains ◽  
Crystallographic Structures

The heterodimeric ligand-binding region of theBovicola ovisecdysone receptor has been crystallized either in the presence of an ecdysteroid or a synthetic methylene lactam insecticide. Two X-ray crystallographic structures, determined at 2.7 Å resolution, show that the ligand-binding domains of both subunits of this receptor, like those of other nuclear receptors, can display significant conformational flexibility. Thermal melt experiments show that while ponasterone A stabilizes the higher order structure of the heterodimer in solution, the methylene lactam destabilizes it. The conformations of the EcR and USP subunits observed in the structure crystallized in the presence of the methylene lactam have not been seen previously in any ecdysone receptor structure and represent a new level of conformational flexibility for these important receptors. Interestingly, the new USP conformation presents an open, unoccupied ligand-binding pocket.

scholarly journals Structural analysis of the SRP Alu domain from Plasmodium falciparum reveals a non-canonical open conformation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Komal Soni ◽  
Georg Kempf ◽  
Karen Manalastas-Cantos ◽  
Astrid Hendricks ◽  
Dirk Flemming ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Binding Sites ◽  
Signal Recognition Particle ◽  
Signal Recognition ◽  
Closed Conformation ◽  
Open Conformation ◽  
Structural Database ◽  
Alu Rna ◽  
Species Specific ◽  
Protozoan Species

AbstractThe eukaryotic signal recognition particle (SRP) contains an Alu domain, which docks into the factor binding site of translating ribosomes and confers translation retardation. The canonical Alu domain consists of the SRP9/14 protein heterodimer and a tRNA-like folded Alu RNA that adopts a strictly ‘closed’ conformation involving a loop-loop pseudoknot. Here, we study the structure of the Alu domain from Plasmodium falciparum (PfAlu), a divergent apicomplexan protozoan that causes human malaria. Using NMR, SAXS and cryo-EM analyses, we show that, in contrast to its prokaryotic and eukaryotic counterparts, the PfAlu domain adopts an ‘open’ Y-shaped conformation. We show that cytoplasmic P. falciparum ribosomes are non-discriminative and recognize both the open PfAlu and closed human Alu domains with nanomolar affinity. In contrast, human ribosomes do not provide high affinity binding sites for either of the Alu domains. Our analyses extend the structural database of Alu domains to the protozoan species and reveal species-specific differences in the recognition of SRP Alu domains by ribosomes.

scholarly journals Nuclear Import of TFIIB Is Mediated by Kap114p, a Karyopherin with Multiple Cargo-binding Domains

2005 ◽  
Vol 16 (7) ◽  
pp. 3200-3210 ◽  
Author(s):  
Jennifer L. Hodges ◽  
Jennifer H. Leslie ◽  
Nima Mosammaparast ◽  
Yurong Guo ◽  
Jeffrey Shabanowitz ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Binding Sites ◽  
Binding Domains ◽  
Transcription Factor Iib ◽  
General Transcription Factor ◽  
Proteomic Approach ◽  
Evolutionarily Conserved ◽  
Import And Export ◽  
Transport Factors

Nuclear import and export is mediated by an evolutionarily conserved family of soluble transport factors, the karyopherins (referred to as importins and exportins). The yeast karyopherin Kap114p has previously been shown to import histones H2A and H2B, Nap1p, and a component of the preinitiation complex (PIC), TBP. Using a proteomic approach, we have identified several potentially new cargoes for Kap114p. These cargoes include another PIC component, the general transcription factor IIB or Sua7p, which interacted directly with Kap114p. Consistent with its role as a Sua7p import factor, deletion of KAP114 led to specific mislocalization of Sua7p to the cytoplasm. An interaction between Sua7p and TBP was also detected in cytosol, raising the possibility that both Sua7p and TBP can be coimported by Kap114p. We have also shown that Kap114p possesses multiple overlapping binding sites for its partners, Sua7p, Nap1p, and H2A and H2B, as well as RanGTP and nucleoporins. In addition, we have assembled an in vitro complex containing Sua7p, Nap1p, and histones H2A and H2B, suggesting that this Kap may import several proteins simultaneously. The import of more than one cargo at a time would increase the efficiency of each import cycle and may allow the regulation of coimported cargoes.

scholarly journals Immunoglobulin-binding domains: Protein L from Peptostreptococcus magnus

2003 ◽  
Vol 31 (3) ◽  
pp. 716-718 ◽  
Author(s):  
N.G. Housden ◽  
S. Harrison ◽  
S.E. Roberts ◽  
J.A. Beckingham ◽  
M. Graille ◽  
...  
Keyword(s):  
Binding Sites ◽  
Protein A ◽  
Cell Wall Protein ◽  
Protein G ◽  
Protein L ◽  
Heavy Chains ◽  
Binding Domains ◽  
Peptostreptococcus Magnus ◽  
Immunoglobulin Binding

Protein L is a multidomain cell-wall protein isolated from Peptostreptococcus magnus. It belongs to a group of proteins that contain repeated domains that are able to bind to Igs without stimulating an immune response, the most characterized of this group being Protein A (Staphylococcus aureus) and Protein G (Streptococcus). Both of these proteins bind predominantly to the interface of CH2-CH3 heavy chains, while Protein L binds exclusively to the VL domain of the κ-chain. The function of these proteins in vivo is not clear but it is thought that they enable the bacteria to evade the host's immune system. Two binding sites for κ-chain on a single Ig-binding domain from Protein L have recently been reported and we give evidence that one site has a 25–55-fold higher affinity for κ-chain than the second site.

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