scholarly journals The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions

2005 ◽  
Vol 33 (8) ◽  
pp. 2661-2675 ◽  
Author(s):  
J.-A. Bruun
Keyword(s):  
Protein Interactions ◽  
Homeodomain Proteins ◽  
The Third ◽  
Recognition Helix ◽  
Paired Class

scholarly journals The toxofilin–actin–PP2C complex of Toxoplasma: identification of interacting domains

2007 ◽  
Vol 401 (3) ◽  
pp. 711-719 ◽  
Author(s):  
Gaelle Jan ◽  
Violaine Delorme ◽  
Violaine David ◽  
Celine Revenu ◽  
Angelita Rebollo ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Actin Filaments ◽  
Function Analysis ◽  
Protozoan Parasite ◽  
Actin Binding ◽  
Protein Protein Interactions ◽  
The Third ◽  
Parasite Motility

Toxofilin is a 27 kDa protein isolated from the human protozoan parasite Toxoplasma gondii, which causes toxoplasmosis. Toxofilin binds to G-actin, and in vitro studies have shown that it controls elongation of actin filaments by sequestering actin monomers. Toxofilin affinity for G-actin is controlled by the phosphorylation status of its Ser53, which depends on the activities of a casein kinase II and a type 2C serine/threonine phosphatase (PP2C). To get insights into the functional properties of toxofilin, we undertook a structure–function analysis of the protein using a combination of biochemical techniques. We identified a domain that was sufficient to sequester G-actin and that contains three peptide sequences selectively binding to G-actin. Two of these sequences are similar to sequences present in several G- and F-actin-binding proteins, while the third appears to be specific to toxofilin. Additionally, we identified two toxofilin domains that interact with PP2C, one of which contains the Ser53 substrate. In addition to characterizing the interacting domains of toxofilin with its partners, the present study also provides information on an in vivo-based approach to selectively and competitively disrupt the protein–protein interactions that are important to parasite motility.

scholarly journals Structure of the Flavivirus Helicase: Implications for Catalytic Activity, Protein Interactions, and Proteolytic Processing

2005 ◽  
Vol 79 (16) ◽  
pp. 10268-10277 ◽  
Author(s):  
Jinhua Wu ◽  
Aloke Kumar Bera ◽  
Richard J. Kuhn ◽  
Janet L. Smith
Keyword(s):  
Protein Interactions ◽  
Yellow Fever Virus ◽  
Proteolytic Processing ◽  
Protein Recognition ◽  
The Third ◽  
Ns3 Protein ◽  
Rna Capping ◽  
A Site ◽  
Viral Polyprotein ◽  
Hydrolysis Of

ABSTRACT Yellow fever virus (YFV), a member of the Flavivirus genus, has a plus-sense RNA genome encoding a single polyprotein. Viral protein NS3 includes a protease and a helicase that are essential to virus replication and to RNA capping. The 1.8-Å crystal structure of the helicase region of the YFV NS3 protein includes residues 187 to 623. Two familiar helicase domains bind nucleotide in a triphosphate pocket without base recognition, providing a site for nonspecific hydrolysis of nucleoside triphosphates and RNA triphosphate. The third, C-terminal domain has a unique structure and is proposed to function in RNA and protein recognition. The organization of the three domains indicates that cleavage of the viral polyprotein NS3-NS4A junction occurs in trans.

The third dimension for protein interactions and complexes

2002 ◽  
Vol 27 (12) ◽  
pp. 633-638 ◽  
Author(s):  
Patrick Aloy ◽  
Robert B. Russell
Keyword(s):  
Protein Interactions ◽  
The Third ◽  
Third Dimension

scholarly journals Sequence-specific targeting of nuclear signal transduction pathways by homeodomain proteins.

1995 ◽  
Vol 15 (6) ◽  
pp. 3318-3326 ◽  
Author(s):  
D A Grueneberg ◽  
K J Simon ◽  
K Brennan ◽  
M Gilman
Keyword(s):  
Dna Binding ◽  
Dna Sequences ◽  
Target Genes ◽  
Serum Response Factor ◽  
Binding Activity ◽  
Homeodomain Proteins ◽  
Extracellular Signals ◽  
Dna Binding Activity ◽  
Paired Class

Cells translate extracellular signals into specific programs of gene expression that reflect their developmental history or identity. We present evidence that one way this interpretation may be performed is by cooperative interactions between serum response factor (SRF) and certain homeodomain proteins. We show that human and Drosophila homeodomain proteins of the paired class have the ability to recruit SRF to DNA sequences not efficiently recognized by SRF on its own, thereby imparting to a linked reporter gene the potential to respond to polypeptide growth factors. This activity requires both the DNA-binding activity of the homeodomain and putative protein-protein contact residues on the exposed surfaces of homeodomain helices 1 and 2. The ability of the homeodomain to impart signal responsiveness is DNA sequence specific, and this specificity differs from the simple DNA-binding specificity of the homeodomain in vitro. The homeodomain imparts response to a spectrum of signals characteristic of the natural SRF-binding site in the c-fos gene. Response to some of these signals is dependent on the secondary recruitment of SRF-dependent ternary complex factors, and we show directly that a homeodomain can promote the recruitment of one such factor, Elk1. We infer that SRF and homeodomains interact cooperatively on DNA and that formation of SRF-homeodomain complexes permits the recruitment of signal-responsive SRF accessory proteins. The ability to route extracellular signals to specific target genes is a novel activity of the homeodomain, which may contribute to the identity function displayed by many homeodomain genes.

scholarly journals Intramolecular domain dynamics regulate synaptic MAGUK protein interactions

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Nils Rademacher ◽  
Benno Kuropka ◽  
Stella-Amrei Kunde ◽  
Markus C Wahl ◽  
Christian Freund ◽  
...  
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Hippocampal Neurons ◽  
Protein Complexes ◽  
Pdz Domain ◽  
Domain Architecture ◽  
Protein Subunit ◽  
Functional Changes ◽  
The Third ◽  
Domain Dynamics

PSD-95 MAGUK family scaffold proteins are multi-domain organisers of synaptic transmission that contain three PDZ domains followed by an SH3-GK domain tandem. This domain architecture allows coordinated assembly of protein complexes composed of neurotransmitter receptors, synaptic adhesion molecules and downstream signalling effectors. Here we show that binding of monomeric CRIPT-derived PDZ3 ligands to the third PDZ domain of PSD-95 induces functional changes in the intramolecular SH3-GK domain assembly that influence subsequent homotypic and heterotypic complex formation. We identify PSD-95 interactors that differentially bind to the SH3-GK domain tandem depending on its conformational state. Among these interactors, we further establish the heterotrimeric G protein subunit Gnb5 as a PSD-95 complex partner at dendritic spines of rat hippocampal neurons. The PSD-95 GK domain binds to Gnb5, and this interaction is triggered by CRIPT-derived PDZ3 ligands binding to the third PDZ domain of PSD-95, unraveling a hierarchical binding mechanism of PSD-95 complex formation.

Drosophila Goosecoid requires a conserved heptapeptide for repression of paired-class homeoprotein activators

Development ◽  
1998 ◽  
Vol 125 (5) ◽  
pp. 937-947 ◽  
Author(s):  
C. Mailhos ◽  
S. Andre ◽  
B. Mollereau ◽  
A. Goriely ◽  
A. Hemmati-Brivanlou ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Organizer Region ◽  
Specific Protein ◽  
Homeodomain Protein ◽  
Protein Protein Interactions ◽  
Stomatogastric Nervous System ◽  
Xenopus Embryos ◽  
Vertebrate Embryos ◽  
Paired Class

Goosecoid (Gsc) is a homeodomain protein expressed in the organizer region of vertebrate embryos. Its Drosophila homologue, D-Gsc, has been implicated in the formation of the Stomatogastric Nervous System. Although there are no apparent similarities between the phenotypes of mutations in the gsc gene in flies and mice, all known Gsc proteins can rescue dorsoanterior structures in ventralized Xenopus embryos. We describe how D-Gsc behaves as a transcriptional repressor in Drosophila cells, acting through specific palindromic HD binding sites (P3K). D-Gsc is a ‘passive repressor’ of activator homeoproteins binding to the same sites and an ‘active repressor’ of activators binding to distinct sites. In addition, D-Gsc is able to strongly repress transcription activated by Paired-class homeoproteins through P3K, via specific protein-protein interactions in what we define as ‘interactive repression’. This form of repression requires the short conserved GEH/eh-1 domain, also present in the Engrailed repressor. Although the GEH/eh-1 domain is necessary for rescue of UV-ventralized Xenopus embryos, it is dispensable for ectopic induction of Xlim-1 expression, demonstrating that this domain is not required for all Gsc functions in vivo. Interactive repression may represent specific interactions among Prd-class homeoproteins, several of which act early during development of invertebrate and vertebrate embryos.

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