The structural basis of Indisulam-mediated recruitment of RBM39 to the DCAF15-DDB1-DDA1 E3 ligase complex

2019 ◽  
Author(s):  
Dirksen E. Bussiere ◽  
Lili Xie ◽  
Honnappa Srinivas ◽  
Wei Shu ◽  
Ashley Burke ◽  
...  
Keyword(s):  
Structural Model ◽  
Complex Structure ◽  
E3 Ligase ◽  
Mrna Splicing ◽  
Splicing Factor ◽  
Structural Basis ◽  
Anti Cancer ◽  
Novel Targets ◽  
Cancer Agent ◽  
Hct116 Cells

AbstractThe anti-cancer agent Indisulam inhibits cell proliferation by causing degradation of RBM39, an essential mRNA splicing factor. Indisulam promotes an interaction between RBM39 and the DCAF15 E3 ligase substrate receptor leading to RBM39 ubiquitination and proteasome-mediated degradation. To delineate the precise mechanism by which Indisulam mediates DCAF15-RBM39 interaction, we solved the DCAF15-DDB1-DDA1-Indisulam-RBM39(RRM2) complex structure to 2.3 Å. DCAF15 has a novel topology which embraces the RBM39(RRM2) domain largely via nonpolar interactions, and Indisulam binds between DCAF15 and RBM39(RRM2) and coordinates additional interactions between the two proteins. Studies with RBM39 point mutants and Indisulam analogs validated the structural model and defined the RBM39 alpha-helical degron motif. The degron is found only in RBM23 and RBM39 and only these proteins were detectably downregulated in Indisulam-treated HCT116 cells. This work further explains how Indisulam induces RBM39 degradation and defines the challenge of harnessing DCAF15 to degrade novel targets.

scholarly journals Structural Basis for Polypyrimidine Tract Recognition by the Essential Pre-mRNA Splicing Factor U2AF65

2006 ◽  
Vol 23 (1) ◽  
pp. 49-59 ◽  
Author(s):  
E. Allen Sickmier ◽  
Katherine E. Frato ◽  
Haihong Shen ◽  
Shanthi R. Paranawithana ◽  
Michael R. Green ◽  
...  
Keyword(s):  
Mrna Splicing ◽  
Splicing Factor ◽  
Structural Basis ◽  
Polypyrimidine Tract

scholarly journals Structural basis for the core-mannan biosynthesis of cell wall fungal-type galactomannan in Aspergillus fumigatus

2020 ◽  
Vol 295 (45) ◽  
pp. 15407-15417
Author(s):  
Daisuke Hira ◽  
Takuya Onoue ◽  
Takuji Oka
Keyword(s):  
Aspergillus Fumigatus ◽  
Structural Model ◽  
Catalytic Domain ◽  
Complex Structure ◽  
Single Amino Acid ◽  
Structural Basis ◽  
Acceptor Substrate ◽  
Substrate Complex ◽  
The Core ◽  
Enzyme Substrate

Fungal cell walls and their biosynthetic enzymes are potential targets for novel antifungal agents. Recently, two mannosyltransferases, namely core-mannan synthases A (CmsA/Ktr4) and B (CmsB/Ktr7), were found to play roles in the core-mannan biosynthesis of fungal-type galactomannan. CmsA/Ktr4 is an α-(1→2)-mannosyltransferase responsible for α-(1→2)-mannan biosynthesis in fungal-type galactomannan, which covers the cell surface of Aspergillus fumigatus. Strains with disrupted cmsA/ktr4 have been shown to exhibit strongly suppressed hyphal elongation and conidiation alongside reduced virulence in a mouse model of invasive aspergillosis, indicating that CmsA/Ktr4 is a potential novel antifungal candidate. In this study we present the 3D structures of the soluble catalytic domain of CmsA/Ktr4, as determined by X-ray crystallography at a resolution of 1.95 Å, as well as the enzyme and Mn2+/GDP complex to 1.90 Å resolution. The CmsA/Ktr4 protein not only contains a highly conserved binding pocket for the donor substrate, GDP-mannose, but also has a unique broad cleft structure formed by its N- and C-terminal regions and is expected to recognize the acceptor substrate, a mannan chain. Based on these crystal structures, we also present a 3D structural model of the enzyme–substrate complex generated using docking and molecular dynamics simulations with α-Man-(1→6)-α-Man-(1→2)-α-Man-OMe as the model structure for the acceptor substrate. This predicted enzyme–substrate complex structure is also supported by findings from single amino acid substitution CmsA/Ktr4 mutants expressed in ΔcmsA/ktr4 A. fumigatus cells. Taken together, these results provide basic information for developing specific α-mannan biosynthesis inhibitors for use as pharmaceuticals and/or pesticides.

Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1

2019 ◽  
Vol 476 (21) ◽  
pp. 3227-3240 ◽  
Author(s):  
Shanshan Wang ◽  
Yanxiang Zhao ◽  
Long Yi ◽  
Minghe Shen ◽  
Chao Wang ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Conformational Changes ◽  
Magnaporthe Oryzae ◽  
Structural Information ◽  
Complex Structure ◽  
Critical Role ◽  
Catalytic Process ◽  
Structural Basis ◽  
Salt Bridges ◽  
Terminal Domain

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.

Benzoxazinoids in human diet: an anti-cancer agent?

2019 ◽  
Author(s):  
B Bhattarai ◽  
SK Steffensen ◽  
PL Gregersen ◽  
JH Jensen ◽  
KD Sørensen ◽  
...  
Keyword(s):  
Human Diet ◽  
Anti Cancer ◽  
Cancer Agent

Future Oncotargets: Targeting Overexpressed Conserved Protein Targets in Androgen Independent Prostate Cancer Cell Lines

2020 ◽  
Vol 20 (8) ◽  
pp. 1017-1027
Author(s):  
Abdul M. Baig ◽  
Zohaib Rana ◽  
Mohammad M. Mannan ◽  
Areeba Khaleeq ◽  
Fizza Nazim ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Lines ◽  
Drug Efflux ◽  
Adapter Proteins ◽  
Cancer Drugs ◽  
Protein Targets ◽  
Anti Cancer ◽  
Drug Efflux Pumps ◽  
Cancer Agent ◽  
Androgen Independent

Background: Targeting evolutionarily conserved proteins in malignant cells and the adapter proteins involved in signalling that generates from such proteins may play a cardinal role in the selection of anti-cancer drugs. Drugs targeting these proteins could be of importance in developing anti-cancer drugs. Objectives: We inferred that drugs like loperamide and promethazine that act as antagonists of proteins conserved in cancer cells like voltage-gated Calcium channels (Cav), Calmodulin (CaM) and drug efflux (ABCB1) pump may have the potential to be re-purposed as an anti-cancer agent in Prostate Cancer (PCa). Methods: Growth and cytotoxic assays were performed by selecting loperamide and promethazine to target Cav, CaM and drug efflux (ABCB1) pumps to elucidate their effects on androgen-independent PC3 and DU145 PCa cell lines. Results: We show that loperamide and promethazine in doses of 80-100μg/ml exert oncocidal effects when tested in DU145 and PC3 cell lines. Diphenhydramine, which shares its targets with promethazine, except the CaM, failed to exhibit oncocidal effects. Conclusion: Anti-cancer effects can be of significance if structural analogues of loperamide and promethazine that specifically target Cav, CaM and ABCB1 drug efflux pumps can be synthesized, or these two drugs could be re-purposed after human trials in PCa.

scholarly journals Structural Basis for the C-Terminal Domain of Mycobacterium tuberculosis Ribosome Maturation Factor RimM to Bind Ribosomal Protein S19

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 597
Author(s):  
Haoran Zhang ◽  
Qiuxiang Zhou ◽  
Chenyun Guo ◽  
Liubin Feng ◽  
Huilin Wang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Ribosomal Protein ◽  
Solution Structure ◽  
Molecular Mechanisms ◽  
Structural Model ◽  
Ribosomal Subunit ◽  
Structural Basis ◽  
Hydrophobic Core ◽  
Terminal Domain ◽  
Ribosomal Protein S19

Multidrug-resistant tuberculosis (TB) is a serious threat to public health, calling for the development of new anti-TB drugs. Chaperon protein RimM, involved in the assembly of ribosomal protein S19 into 30S ribosomal subunit during ribosome maturation, is a potential drug target for TB treatment. The C-terminal domain (CTD) of RimM is primarily responsible for binding S19. However, both the CTD structure of RimM from Mycobacterium tuberculosis (MtbRimMCTD) and the molecular mechanisms underlying MtbRimMCTD binding S19 remain elusive. Here, we report the solution structure, dynamics features of MtbRimMCTD, and its interaction with S19. MtbRimMCTD has a rigid hydrophobic core comprised of a relatively conservative six-strand β-barrel, tailed with a short α-helix and interspersed with flexible loops. Using several biophysical techniques including surface plasmon resonance (SPR) affinity assays, nuclear magnetic resonance (NMR) assays, and molecular docking, we established a structural model of the MtbRimMCTD–S19 complex and indicated that the β4-β5 loop and two nonconserved key residues (D105 and H129) significantly contributed to the unique pattern of MtbRimMCTD binding S19, which might be implicated in a form of orthogonality for species-dependent RimM–S19 interaction. Our study provides the structural basis for MtbRimMCTD binding S19 and is beneficial to the further exploration of MtbRimM as a potential target for the development of new anti-TB drugs.

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