scholarly journals Identification of a second binding site on the TRIM25 B30.2 domain

2018 ◽  
Vol 475 (2) ◽  
pp. 429-440 ◽  
Author(s):  
Akshay A. D'Cruz ◽  
Nadia J. Kershaw ◽  
Thomas J. Hayman ◽  
Edmond M. Linossi ◽  
Jessica J. Chiang ◽  
...  
Keyword(s):  
Influenza A ◽  
Coiled Coil ◽  
Binding Mode ◽  
Innate Immune ◽  
Interaction Domain ◽  
Binding Interface ◽  
Α Helix ◽  
B30.2 Domain ◽  
Inducible Gene

The retinoic acid-inducible gene-I (RIG-I) receptor recognizes short 5′-di- and triphosphate base-paired viral RNA and is a critical mediator of the innate immune response against viruses such as influenza A, Ebola, HIV and hepatitis C. This response is reported to require an orchestrated interaction with the tripartite motif 25 (TRIM25) B30.2 protein-interaction domain. Here, we present a novel second RIG-I-binding interface on the TRIM25 B30.2 domain that interacts with CARD1 and CARD2 (caspase activation and recruitment domains) of RIG-I and is revealed by the removal of an N-terminal α-helix that mimics dimerization of the full-length protein. Further characterization of the TRIM25 coiled-coil and B30.2 regions indicated that the B30.2 domains move freely on a flexible tether, facilitating RIG-I CARD recruitment. The identification of a dual binding mode for the TRIM25 B30.2 domain is a first for the SPRY/B30.2 domain family and may be a feature of other SPRY/B30.2 family members.

scholarly journals A Two-Site Interaction Underpins TRIM25 Activation of the RIG-I Anti-Viral Response

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1580-1580
Author(s):  
Akshay A D'Cruz ◽  
Nadia J Kershaw ◽  
Edmond M Linossi ◽  
Jessica J Chiang ◽  
May K Wang ◽  
...  
Keyword(s):  
Binding Site ◽  
Influenza A ◽  
Structural Changes ◽  
Conflicts Of Interest ◽  
Membrane Integrity ◽  
Binding Mode ◽  
Innate Immune ◽  
Erythroid Cell ◽  
Cell Membrane Integrity ◽  
B30.2 Domain

Abstract SPRY/B30.2 domain-containing proteins are found in 103 human proteins that regulate numerous cellular processes including RNA processing, histone methylation, red blood cell membrane integrity, terminal erythroid cell differentiation and innate immune responses. Despite an increased understanding of SPRY/B30.2 domain function, some confusion remains as to the precise domain boundaries, the number and location of binding sites, and importantly how activation of these domains contribute to signal transduction. The B30.2 domain of tripartite motif 25 (TRIM25) interacts with the viral RNA sensor retinoic acid-inducible gene I (RIG-I), facilitating the formation of a RIG-I tetramer, which is required for activation of the innate immune response against RNA viruses such as influenza A, measles, HIV and hepatitis C. Here we have investigated the biochemical and structural changes associated with the activation of TRIM25 in the context of RIG-I binding. We solved a 1.8 Å crystal structure of the TRIM25 B30.2 domain and identified a putative RIG-I-binding site, which was confirmed by mutagenesis and functional analyses. Further mutagenesis identified a second site on the opposing face of the B30.2 domain that also specifically interacts with RIG-I. While the CARD1 domain of RIG-I is known to interact with the B30.2 domain of TRIM25, our data suggest that a conformational change within the CARD2 domain of RIG-I enables it to also interact with the B30.2 domain of TRIM25. We propose that both RIG-I CARDs interact with sites on opposing sides of the TRIM25 B30.2 domain to form a TRIM25/RIG-I complex that facilitates RIG-I tetramerisation and activation. The characterization of a dual binding mode for the TRIM25 B30.2 domain is a first for the SPRY/B30.2 domain family. Disease-associated polymorphisms of Pyrin, involved in Familial Mediterranean Fever, and mutational analyses of TRIM5a, required for HIV restriction, suggest that a second binding site may be a characteristic feature of other B30.2-containing TRIM proteins, and may facilitate the formation of large oligomeric complexes that are important for inflammasome function and HIV capsid destruction. Disclosures No relevant conflicts of interest to declare.

scholarly journals Cytoplasm and Beyond: Dynamic Innate Immune Sensing of Influenza A Virus by RIG-I

2019 ◽  
Vol 93 (8) ◽  
Author(s):  
GuanQun Liu ◽  
Yan Zhou
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Innate Immune ◽  
Cytoplasmic Localization ◽  
Full Spectrum ◽  
Cytoplasmic Rna ◽  
Immune Sensing ◽  
Rna Ligands ◽  
Innate Immune Sensing ◽  
Inducible Gene

ABSTRACTInnate immune sensing of influenza A virus (IAV) requires retinoic acid-inducible gene I (RIG-I), a fundamental cytoplasmic RNA sensor. How RIG-I’s cytoplasmic localization reconciles with the nuclear replication nature of IAV is poorly understood. Recent findings provide advanced insights into the spatiotemporal RIG-I sensing of IAV and highlight the contribution of various RNA ligands to RIG-I activation. Understanding a compartment-specific RIG-I-sensing paradigm would facilitate the identification of the full spectrum of physiological RIG-I ligands produced during IAV infection.

Generation and characterization of the antibacterial activity of a novel hybrid antimicrobial peptide comprising functional domains from different insect cecropins

2009 ◽  
Vol 55 (5) ◽  
pp. 520-528 ◽  
Author(s):  
Richard M. Plunkett ◽  
Stuart I. Murray ◽  
Carl A. Lowenberger
Keyword(s):  
Antibacterial Activity ◽  
Innate Immune ◽  
Antimicrobial Compounds ◽  
Target Specificity ◽  
Hybrid Molecule ◽  
Parent Molecule ◽  
Gram Positive Bacteria ◽  
Cecropin A ◽  
Α Helix

The search for new antimicrobial compounds involves finding novel sources of chemotherapeutic compounds or manipulating and combining structures from existing molecules. Small antimicrobial peptides (AMPs) are components of innate immune defenses characterized in greatest detail in insect-derived AMPs. We have generated hybrid AMPs (hAMPs) by combining functional motifs from different insect AMPs as a proof of principle that we can generate molecules with lower minimum inhibitory concentrations, and with different activity and target specificity than either parent molecule. A two-helix, cecropin-like hAMP was created by linking the N-terminal α helix of cecropin A from Aedes aegypti to the C-terminal α helix of cecropin A1 from Drosophila melanogaster . This molecule exhibits antibacterial activity at sub-micromolar concentrations with a target specificity that differs from either parent molecule. Antibacterial activity of the hybrid molecule was found to be greater against Gram-negative than Gram-positive bacteria. No hemolysis was observed in sheep red blood cells exposed to concentrations up to 50 µmol/L, suggesting the peptide is not detrimental to eukaryotic cells.

scholarly journals Structural insights into phosphoinositide 3-kinase activation by the influenza A virus NS1 protein

2010 ◽  
Vol 107 (5) ◽  
pp. 1954-1959 ◽  
Author(s):  
Benjamin G. Hale ◽  
Philip S. Kerry ◽  
David Jackson ◽  
Bernard L. Precious ◽  
Alexander Gray ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Coiled Coil ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Ns1 Protein ◽  
Influenza A Viruses ◽  
Phosphoinositide 3 Kinase ◽  
Α Helix

Seasonal epidemics and periodic worldwide pandemics caused by influenza A viruses are of continuous concern. The viral nonstructural (NS1) protein is a multifunctional virulence factor that antagonizes several host innate immune defenses during infection. NS1 also directly stimulates class IA phosphoinositide 3-kinase (PI3K) signaling, an essential cell survival pathway commonly mutated in human cancers. Here, we present a 2.3-Å resolution crystal structure of the NS1 effector domain in complex with the inter-SH2 (coiled-coil) domain of p85β, a regulatory subunit of PI3K. Our data emphasize the remarkable isoform specificity of this interaction, and provide insights into the mechanism by which NS1 activates the PI3K (p85β:p110) holoenzyme. A model of the NS1:PI3K heterotrimeric complex reveals that NS1 uses the coiled-coil as a structural tether to sterically prevent normal inhibitory contacts between the N-terminal SH2 domain of p85β and the p110 catalytic subunit. Furthermore, in this model, NS1 makes extensive contacts with the C2/kinase domains of p110, and a small acidic α-helix of NS1 sits adjacent to the highly basic activation loop of the enzyme. During infection, a recombinant influenza A virus expressing NS1 with charge-disruption mutations in this acidic α-helix is unable to stimulate the production of phosphatidylinositol 3,4,5-trisphosphate or the phosphorylation of Akt. Despite this, the charge-disruption mutations in NS1 do not affect its ability to interact with the p85β inter-SH2 domain in vitro. Overall, these data suggest that both direct binding of NS1 to p85β (resulting in repositioning of the N-terminal SH2 domain) and possible NS1:p110 contacts contribute to PI3K activation.

Scorpion toxin-potassium channel interaction law and its applications.

2020 ◽  
Vol 01 ◽  
Author(s):  
Zheng Zuo ◽  
Zongyun Chen ◽  
Zhijian Cao ◽  
Wenxin Li ◽  
Yingliang Wu
Keyword(s):  
Potassium Channel ◽  
Scorpion Toxin ◽  
Scorpion Toxins ◽  
Toxin Binding ◽  
Channel Interaction ◽  
Binding Interface ◽  
Α Helix ◽  
Interaction Law ◽  
Binding Interfaces ◽  
Β Sheet

: The scorpion toxins are the largest potassium channel-blocking peptide family. The understanding of toxin binding interfaces is usually restricted by two classical binding interfaces: one is the toxin α-helix motif, the other is the antiparallel β-sheet motif. In this review, such traditional knowledge was updated by another two different binding interfaces: one is BmKTX toxin using the turn motif between the α-helix and antiparallel β-sheet domains as the binding interface, the other is Ts toxin using turn motif between the β-sheet in the N-terminal and α-helix domains as the binding interface. Their interaction analysis indicated that the scarce negatively charged residues in the scorpion toxins played a critical role in orientating the toxin binding interface. In view of the toxin negatively charged amino acids as “binding interface regulator”, the law of scorpion toxin-potassium channel interaction was proposed, that is, the polymorphism of negatively charged residue distribution determines the diversity of toxin binding interfaces. Such law was used to develop scorpion toxin-potassium channel recognition control technique. According to this technique, three Kv1.3 channel-targeted peptides, using BmKTX as the template, were designed with the distinct binding interfaces from that of BmKTX through modulating the distribution of toxin negatively charged residues. In view of the potassium channel as the common targets of different animal toxins, the proposed law was also shown to helpfully orientate the binding interfaces of other animal toxins. Clearly, the toxin-potassium channel interaction law would strongly accelerate the research and development of different potassium channelblocking animal toxins in the future.

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