scholarly journals The C Terminus of Rotavirus VP4 Protein Contains an Actin Binding Domain Which Requires Cooperation with the Coiled-Coil Domain for Actin Remodeling

2018 ◽  
Vol 93 (1) ◽  
Author(s):  
Wilfried Condemine ◽  
Thibaut Eguether ◽  
Nathalie Couroussé ◽  
Catherine Etchebest ◽  
Agnes Gardet ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Coiled Coil ◽  
Binding Domain ◽  
Spike Protein ◽  
Actin Binding ◽  
Intestinal Cells ◽  
Actin Remodeling ◽  
Coiled Coil Domain ◽  
C Terminus ◽  
Actin Binding Domain

ABSTRACTThe interactions between viruses and actin cytoskeleton have been widely studied. We showed that rotaviruses remodel microfilaments in intestinal cells and demonstrated that this was due to the VP4 spike protein. Microfilaments mainly occur in the apical domain of infected polarized enterocytes and favor the polarized apical exit of viral progeny. The present work aims at the identification of molecular determinants of actin-VP4 interactions. We used various deletion mutants of VP4 that were transfected into Cos-7 cells and analyzed interactions by immunofluorescence confocal microscopy. It has been established that the C-terminal part of VP4 is embedded within viral particles when rotavirus assembles. The use of specific monoclonal antibodies demonstrated that VP4 is expressed in different forms in infected cells: classically as spike on the outer layer of virus particles, but also as free soluble protein in the cytosol. The C terminus of free VP4 was identified as interacting with actin microfilaments. The VP4 actin binding domain is unable to promote microfilament remodeling by itself; the coiled-coil domain is also required in this process. This actin-binding domain was shown to dominate a previously identified peroxisomal targeting signal, located in the three last amino acids of VP4. The newly identified actin-binding domain is highly conserved in rotavirus strains from species A, B, and C, suggesting that actin binding and remodeling is a general strategy for rotavirus exit. This provides a novel mechanism of protein-protein interactions, not involving cell signaling pathways, to facilitate rotavirus exit.IMPORTANCERotaviruses are causal agents of acute infantile viral diarrhea. In intestinal cells,in vitroas well asin vivo, virus assembly and exit do not imply cell lysis but rely on an active process in which the cytoskeleton plays a major role. We describe here a novel molecular mechanism by which the rotavirus spike protein VP4 drives actin remodeling. This relies on the fact that VP4 occurs in different forms. Besides its structural function within the virion, a large proportion of VP4 is expressed as free protein. Here, we show that free VP4 possesses a functional actin-binding domain. This domain, in coordination with a coiled-coil domain, promotes actin cytoskeleton remodeling, thereby providing the capacity to destabilize the cell membrane and allow efficient rotavirus exit.

NUANCE, a giant protein connecting the nucleus and actin cytoskeleton

2002 ◽  
Vol 115 (15) ◽  
pp. 3207-3222 ◽  
Author(s):  
Yen-Yi Zhen ◽  
Thorsten Libotte ◽  
Martina Munck ◽  
Angelika A. Noegel ◽  
Elena Korenbaum
Keyword(s):  
Actin Cytoskeleton ◽  
Transmembrane Domain ◽  
Coiled Coil ◽  
Peripheral Blood Lymphocytes ◽  
Binding Domain ◽  
Actin Binding ◽  
Actin Binding Domain ◽  
Microfilament System

NUANCE (NUcleus and ActiN Connecting Element) was identified as a novel protein with an α-actinin-like actin-binding domain. A human 21.8 kb cDNA of NUANCE spreads over 373 kb on chromosome 14q22.1-q22.3. The cDNA sequence predicts a 796 kDa protein with an N-terminal actin-binding domain, a central coiled-coil rod domain and a predicted C-terminal transmembrane domain. High levels of NUANCE mRNA were detected in the kidney, liver,stomach, placenta, spleen, lymphatic nodes and peripheral blood lymphocytes. At the subcellular level NUANCE is present predominantly at the outer nuclear membrane and in the nucleoplasm. Domain analysis shows that the actin-binding domain binds to Factin in vitro and colocalizes with the actin cytoskeleton in vivo as a GFP-fusion protein. The C-terminal transmembrane domain is responsible for the targeting the nuclear envelope. Thus, NUANCE is the firstα-actinin-related protein that has the potential to link the microfilament system with the nucleus.

scholarly journals A Coiled-Coil Domain of Melanophilin Is Essential for Myosin Va Recruitment and Melanosome Transport in Melanocytes

2006 ◽  
Vol 17 (11) ◽  
pp. 4720-4735 ◽  
Author(s):  
Alistair N. Hume ◽  
Abul K. Tarafder ◽  
José S. Ramalho ◽  
Elena V. Sviderskaya ◽  
Miguel C. Seabra
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Actin Binding ◽  
Binding Studies ◽  
Null Cell ◽  
Coiled Coil Region ◽  
Actin Binding Domain ◽  
Transport Assay ◽  
Myosin Va

Melanophilin (Mlph) regulates retention of melanosomes at the peripheral actin cytoskeleton of melanocytes, a process essential for normal mammalian pigmentation. Mlph is proposed to be a modular protein binding the melanosome-associated protein Rab27a, Myosin Va (MyoVa), actin, and microtubule end-binding protein (EB1), via distinct N-terminal Rab27a-binding domain (R27BD), medial MyoVa-binding domain (MBD), and C-terminal actin-binding domain (ABD), respectively. We developed a novel melanosome transport assay using a Mlph-null cell line to study formation of the active Rab27a:Mlph:MyoVa complex. Recruitment of MyoVa to melanosomes correlated with rescue of melanosome transport and required intact R27BD together with MBD exon F–binding region (EFBD) and unexpectedly a potential coiled-coil forming sequence within ABD. In vitro binding studies indicate that the coiled-coil region enhances binding of MyoVa by Mlph MBD. Other regions of Mlph reported to interact with MyoVa globular tail, actin, or EB1 are not essential for melanosome transport rescue. The strict correlation between melanosomal MyoVa recruitment and rescue of melanosome distribution suggests that stable interaction with Mlph and MyoVa activation are nondissociable events. Our results highlight the importance of the coiled-coil region together with R27BD and EFBD regions of Mlph in the formation of the active melanosomal Rab27a-Mlph-MyoVa complex.

scholarly journals Microtubule Actin Cross-Linking Factor (Macf)

1999 ◽  
Vol 147 (6) ◽  
pp. 1275-1286 ◽  
Author(s):  
Conrad L. Leung ◽  
Dongming Sun ◽  
Min Zheng ◽  
David R. Knowles ◽  
Ronald K.H. Liem
Keyword(s):  
Calcium Binding ◽  
Coiled Coil ◽  
Specific Protein ◽  
Binding Domain ◽  
Full Length ◽  
Actin Binding ◽  
Cross Linking ◽  
Actin Binding Domain

We cloned and characterized a full-length cDNA of mouse actin cross-linking family 7 (mACF7) by sequential rapid amplification of cDNA ends–PCR. The completed mACF7 cDNA is 17 kb and codes for a 608-kD protein. The closest relative of mACF7 is the Drosophila protein Kakapo, which shares similar architecture with mACF7. mACF7 contains a putative actin-binding domain and a plakin-like domain that are highly homologous to dystonin (BPAG1-n) at its NH2 terminus. However, unlike dystonin, mACF7 does not contain a coiled–coil rod domain; instead, the rod domain of mACF7 is made up of 23 dystrophin-like spectrin repeats. At its COOH terminus, mACF7 contains two putative EF-hand calcium-binding motifs and a segment homologous to the growth arrest–specific protein, Gas2. In this paper, we demonstrate that the NH2-terminal actin-binding domain of mACF7 is functional both in vivo and in vitro. More importantly, we found that the COOH-terminal domain of mACF7 interacts with and stabilizes microtubules. In transfected cells full-length mACF7 can associate not only with actin but also with microtubules. Hence, we suggest a modified name: MACF (microtubule actin cross-linking factor). The properties of MACF are consistent with the observation that mutations in kakapo cause disorganization of microtubules in epidermal muscle attachment cells and some sensory neurons.

scholarly journals Tissue Expression and Actin Binding of a Novel N-Terminal Utrophin Isoform

2011 ◽  
Vol 2011 ◽  
pp. 1-18
Author(s):  
Richard A. Zuellig ◽  
Beat C. Bornhauser ◽  
Ralf Amstutz ◽  
Bruno Constantin ◽  
Marcus C. Schaub
Keyword(s):  
Actin Cytoskeleton ◽  
Tissue Expression ◽  
Protein Product ◽  
Binding Domain ◽  
Actin Binding ◽  
Rat Tissues ◽  
Cortical Actin ◽  
Actin Binding Domain ◽  
Spectrin Repeats

Utrophin and dystrophin present two large proteins that link the intracellular actin cytoskeleton to the extracellular matrix via the C-terminal-associated protein complex. Here we describe a novel short N-terminal isoform of utrophin and its protein product in various rat tissues (N-utro, 62 kDa, amino acids 1–539, comprising the actin-binding domain plus the first two spectrin repeats). Using different N-terminal recombinant utrophin fragments, we show that actin binding exhibits pronounced negative cooperativity (affinity constantsK1=∼5×106andK2=∼1×105 M-1) and is Ca2+-insensitive. Expression of the different fragments in COS7 cells and in myotubes indicates that the actin-binding domain alone binds exlusively to actin filaments. The recombinant N-utro analogue binds in vitro to actin and in the cells associates to the membranes. The results indicate that N-utro may be responsible for the anchoring of the cortical actin cytoskeleton to the membranes in muscle and other tissues.

Fluorescent protein-based reporters of the actin cytoskeleton in living plant cells: Fluorophore variant, actin binding domain, and promoter considerations

Cytoskeleton ◽  
2014 ◽  
Vol 71 (5) ◽  
pp. 311-327 ◽  
Author(s):  
Julia Dyachok ◽  
J. Alan Sparks ◽  
Fuqi Liao ◽  
Yuh-Shuh Wang ◽  
Elison B. Blancaflor
Keyword(s):  
Actin Cytoskeleton ◽  
Fluorescent Protein ◽  
Plant Cells ◽  
Binding Domain ◽  
Actin Binding ◽  
Living Plant ◽  
Actin Binding Domain

scholarly journals Focal segmental glomerulosclerosis ACTN4 mutants binding to actin: regulation by phosphomimetic mutations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hanshuang Shao ◽  
Bentley Wingert ◽  
Astrid Weins ◽  
Martin R. Pollak ◽  
Carlos Camacho ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Focal Segmental Glomerulosclerosis ◽  
Actin Filaments ◽  
Binding Activity ◽  
Binding Domain ◽  
Actin Binding ◽  
Dominant Form ◽  
Cell Functions ◽  
Segmental Glomerulosclerosis ◽  
Actin Binding Domain

Abstract Natural mutations such as lysine 255 to glutamic acid (K to E), threonine 259 to isoleucine (T to I) and serine 262 to proline (S to P) that occur within the actin binding domain of alpha-actinin-4 (ACTN4) cause an autosomal dominant form of focal segmental glomerulosclerosis (FSGS) in affected humans. This appears due to elevated actin binding propensity in podocytes resulting in a ‘frozen’ cytoskeleton. What is challenging is how this cellular behavior would be compatible with other cell functions that rely on cytoskeleton plasticity. Our previous finding revealed that wild type ACTN4 can be phosphorylated at tyrosine 4 and 31 upon stimulation by epidermal growth factor (EGF) to reduce the binding to actin cytoskeleton. We queried whether the elevated actin binding activity of FSGS mutants can be downregulated by EGF-mediated phosphorylation, to discern a mechanism by which the actin-cytoskeleton can be released in FSGS. In this manuscript, we first constructed variants with Y4/31E to mimic the phosphorylation at tyrosines 4 and 31 based on earlier modeling simulations that predicted that this would bury the actin binding domains and lead to a decrease in actin binding activity. We found that Y4/31E significantly reduced the actin binding activity of K255E, T259I and S262P, dramatically preventing them from aggregating in, and inhibiting motility of, podocytes, fibroblasts and melanoma cells. A putative kinase target site at Y265 in the actin binding domain was also generated as a phosphomimetic ACTN4 Y265E that demonstrated even greater binding to actin filaments than K255E and the other FSGS mutants. That the tyrosine kinase regulation of FSGS mutation binding to actin filaments can occur in cells was shown by phosphorylation on Y4 and Y31 of the K225E after extended exposure of cells to EGF, with a decrease in ACTN4 aggregates in fibroblasts. These findings will provide evidence for targeting the N-termini of FSGS ACTN4 mutants to downregulate their actin binding activities for ameliorating the glomerulosclerotic phenotype of patients.

The C-Terminus of Alpha Spectrin Binds Protein 4.2 and Is Necessary for Optimal Spectrin-Actin Binding.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 810-810 ◽  
Author(s):  
Catherine Korsgren ◽  
Connie S. Birkenmeier ◽  
Jane E. Barker ◽  
Luanne L. Peters ◽  
Samuel E. Lux
Keyword(s):  
Amino Acids ◽  
Membrane Skeleton ◽  
Binding Domain ◽  
Actin Binding ◽  
C Terminus ◽  
Actin Binding Domain ◽  
Ef Hand ◽  
Protein 4.2 ◽  
Protein 4.1R ◽  
Β Chain

Abstract The red blood cell (RBC) membrane skeleton is composed principally of short F-actin filaments crosslinked by α2β2-spectrin tetramers with the assistance of protein 4.1R. Actin and 4.1R bind to the actin-binding domain (βABD) at the N-terminus of the spectrin β-chain. The adjacent, C-terminal end of α-spectrin, contains a calmodulin-like domain (αCML, aa 2262–2418) that is also called the EF hand domain and is thought to be inert or vestigial. However, the sph1J/sph1J mouse, which has severe hereditary spherocytosis and unstable RBC membranes, makes a mutant α-spectrin that lacks the last 13 amino acids (αCMLΔC13), showing that the domain has some important function. To investigate this function we “fished” for interacting proteins using glutathione-S-transferase (GST)-fused to the CML domain—either the wildtype (αGST-CML) or sph1J (αGST-CMLΔC13). αGST-CML retrieved protein 4.2 from a 2M Tris HCl extract of spectrin-actin depleted human RBC membranes. Protein 4.2 bound αGST-CML with high affinity (Kd = 2.7 x 10−7M) but did not bind αGST-CMLΔC13. Binding was abolished by 1 mM Ca2+, which converts the CML domain to the liganded conformation. The binding site on protein 4.2 localized, at least partly, to amino acids 411–492. Because red cells lacking protein 4.2 are not as severely affected as sph1J/sph1J RBCs, we also tested the effect of the αCMLΔC13 mutation on spectrin-actin binding. A minispectrin was prepared containing the actin-binding domain plus the first four spectrin repeats of the β-chain, combined with the CML domain (±ΔC13) and the last four repeats of the α-chain. The normal and mutant minispectrins were incubated with protein 4.1R, F-actin, or both proteins. The results were striking. The minispectrin containing the normal CML domain bound actin in the presence of protein 4.1R, but the minispectrin containing the mutant CML domain did not. Similarly, the mutant minispectrin was defective in its ability to bind 125I-4.1R in the presence of a constant amount of F-actin. However, the mutation did not affect binding of the minispectrin to protein 4.1R in the absence of actin. We have not yet tested whether protein 4.2 or Ca2+ modulate the effects of the CML domain on spectrin-actin binding. In summary, these experiments clearly show that the calmodulin-like (EF hand) domain of α-spectrin, which was previously considered inert, binds protein 4.2 and also contributes to spectrin-actin binding in the presence of protein 4.1R. Further experiments will be needed to determine whether the CML domain binds actin directly or strengthens the binding of the adjacent actin-binding domain.

scholarly journals CPn0572, the C. pneumoniae ortholog of TarP, reorganizes the actin cytoskeleton via a newly identified F-actin binding domain and recruitment of vinculin

PLoS ONE ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. e0210403 ◽  
Author(s):  
Corinna Braun ◽  
Abel R. Alcázar-Román ◽  
Alexandra Laska ◽  
Katja Mölleken ◽  
Ursula Fleig ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Binding Domain ◽  
Actin Binding ◽  
Actin Binding Domain

scholarly journals The BPAG1 locus

2001 ◽  
Vol 154 (4) ◽  
pp. 691-698 ◽  
Author(s):  
Conrad L. Leung ◽  
Min Zheng ◽  
Susan M. Prater ◽  
Ronald K.H. Liem
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Mutant Mice ◽  
Actin Binding ◽  
Spectrin Repeat ◽  
Binding Domains ◽  
Microtubule Binding Domain ◽  
Actin Binding Domain ◽  
Skin Fragility ◽  
Interaction Domains

Bullous pemphigoid antigen 1 (BPAG1) is a member of the plakin family with cytoskeletal linker properties. Mutations in BPAG1 cause sensory neuron degeneration and skin fragility in mice. We have analyzed the BPAG1 locus in detail and found that it encodes different interaction domains that are combined in tissue-specific manners. These domains include an actin-binding domain (ABD), a plakin domain, a coiled coil (CC) rod domain, two different potential intermediate filament–binding domains (IFBDs), a spectrin repeat (SR)-containing rod domain, and a microtubule-binding domain (MTBD). There are at least three major forms of BPAG1: BPAG1-e (302 kD), BPAG1-a (615 kD), and BPAG1-b (834 kD). BPAG1-e has been described previously and consists of the plakin domain, the CC rod domain, and the first IFBD. It is the primary epidermal BPAG1 isoform, and its absence that is the likely cause of skin fragility in mutant mice. BPAG1-a is the major isoform in the nervous system and a homologue of the microtubule actin cross-linking factor, MACF. BPAG1-a is composed of the ABD, the plakin domain, the SR-containing rod domain, and the MTBD. The absence of BPAG1-a is the likely cause of sensory neurodegeneration in mutant mice. BPAG1-b is highly expressed in muscles, and has extra exons encoding a second IFBD between the plakin and SR-containing rod domains of BPAG1-a.

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