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The WH2 Domain and Actin Nucleation: Necessary but Insufficient. Trends Biochem Sci 2016; 41:478-490. [PMID: 27068179 DOI: 10.1016/j.tibs.2016.03.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/18/2016] [Accepted: 03/11/2016] [Indexed: 11/22/2022]
Abstract
Two types of sequences, proline-rich domains (PRDs) and the WASP-homology 2 (WH2) domain, are found in most actin filament nucleation and elongation factors discovered thus far. PRDs serve as a platform for protein-protein interactions, often mediating the binding of profilin-actin. The WH2 domain is an abundant actin monomer-binding motif comprising ∼17 amino acids. It frequently occurs in tandem repeats, and functions in nucleation by recruiting actin subunits to form the polymerization nucleus. It is found in Spire, Cordon Bleu (Cobl), Leiomodin (Lmod), Arp2/3 complex activators (WASP, WHAMM, WAVE, etc.), the bacterial nucleators VopL/VopF and Sca2, and some formins. Yet, it is argued here that the WH2 domain plays only an auxiliary role in nucleation, always synergizing with other domains or proteins for this activity.
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52
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Yang XD, Zhao SF, Zhang Q, Li W, Wang YX, Hong XW, Hu QG. Gelsolin rs1078305 and rs10818524 polymorphisms were associated with risk of oral squamous cell carcinoma in a Chinese Han population. Biomarkers 2016; 21:267-71. [PMID: 26848502 DOI: 10.3109/1354750x.2015.1134664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Gelsolin (GSN) is one of the most abundant actin-binding proteins, and is involved in cancer development and progression. PATIENTS AND METHODS A hospital-based case-control study including 201 patients with OSCC and 199 healthy controls was conducted. Seventeen single-nucleotide polymorphisms (SNPs) of GSN were investigated by Sequenom Mass ARRAY and iPLEX-MALDI-TOF technology. RESULTS Through comparison of the 17 SNPs on GSN gene between the two groups, SNP rs1078305 and rs10818524 were verified to be significantly associated with an increased risk of OSCC. For GSN rs1078305, the TT genotype was associated with increased risk for OSCC (OR = 1.92, 95% CI = 1.11-3.32, p = 0.028). CT/TT variants were also associated with increased risk for OSCC compared to the CC genotype (OR = 1.83, 95% CI = 1.25-3.84, p = 0.032). CONCLUSION The rs1078305 and rs10818524 SNPs of GSN were associated with increased risk for OSCC development in a Chinese Han population.
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Affiliation(s)
- Xu-Dong Yang
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Su-Feng Zhao
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Qian Zhang
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Wei Li
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Yu-Xin Wang
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Xiao-Wei Hong
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
| | - Qin-Gang Hu
- a Department of Oral and Maxillofacial Surgery , Nanjing Stomatological Hospital, Medical School of Nanjing University , Nanjing , PR China
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Izoré T, Kureisaite-Ciziene D, McLaughlin SH, Löwe J. Crenactin forms actin-like double helical filaments regulated by arcadin-2. eLife 2016; 5:e21600. [PMID: 27852434 PMCID: PMC5173319 DOI: 10.7554/elife.21600] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 11/14/2016] [Indexed: 01/27/2023] Open
Abstract
The similarity of eukaryotic actin to crenactin, a filament-forming protein from the crenarchaeon Pyrobaculum calidifontis supports the theory of a common origin of Crenarchaea and Eukaryotes. Monomeric structures of crenactin and actin are similar, although their filament architectures were suggested to be different. Here we report that crenactin forms bona fide double helical filaments that show exceptional similarity to eukaryotic F-actin. With cryo-electron microscopy and helical reconstruction we solved the structure of the crenactin filament to 3.8 Å resolution. When forming double filaments, the 'hydrophobic plug' loop in crenactin rearranges. Arcadin-2, also encoded by the arcade gene cluster, binds tightly with its C-terminus to the hydrophobic groove of crenactin. Binding is reminiscent of eukaryotic actin modulators such as cofilin and thymosin β4 and arcadin-2 is a depolymeriser of crenactin filaments. Our work further supports the theory of shared ancestry of Eukaryotes and Crenarchaea.
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Affiliation(s)
- Thierry Izoré
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | | | - Stephen H McLaughlin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom,
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Tetlow DJ, Winder SJ, Aïssa C. The synthesis and biological evaluation of a kabiramide C fragment modified with a WH2 consensus actin-binding motif as a potential disruptor of the actin cytoskeleton. Chem Commun (Camb) 2016; 52:807-10. [DOI: 10.1039/c5cc06081h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite its low affinity for actin monomers, a fragment of kabiramide C disrupts actin filamentsin vitroand in cells.
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56
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Bhargav SP, Vahokoski J, Kallio JP, Torda AE, Kursula P, Kursula I. Two independently folding units of Plasmodium profilin suggest evolution via gene fusion. Cell Mol Life Sci 2015; 72:4193-203. [PMID: 26012696 PMCID: PMC11113795 DOI: 10.1007/s00018-015-1932-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 10/23/2022]
Abstract
Gene fusion is a common mechanism of protein evolution that has mainly been discussed in the context of multidomain or symmetric proteins. Less is known about fusion of ancestral genes to produce small single-domain proteins. Here, we show with a domain-swapped mutant Plasmodium profilin that this small, globular, apparently single-domain protein consists of two foldons. The separation of binding sites for different protein ligands in the two halves suggests evolution via an ancient gene fusion event, analogous to the formation of multidomain proteins. Finally, the two fragments can be assembled together after expression as two separate gene products. The possibility to engineer both domain-swapped dimers and half-profilins that can be assembled back to a full profilin provides perspectives for engineering of novel protein folds, e.g., with different scaffolding functions.
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Affiliation(s)
| | - Juha Vahokoski
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014, Oulu, Finland
| | - Juha Pekka Kallio
- Helmholtz Centre for Infection Research, Notkestrasse 85, 22607, Hamburg, Germany
- German Electron Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg, Germany
| | - Andrew E Torda
- Centre for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146, Hamburg, Germany
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014, Oulu, Finland
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014, Oulu, Finland
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway
| | - Inari Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014, Oulu, Finland.
- Helmholtz Centre for Infection Research, Notkestrasse 85, 22607, Hamburg, Germany.
- German Electron Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg, Germany.
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
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Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs. Nat Commun 2015; 5:3308. [PMID: 24518936 DOI: 10.1038/ncomms4308] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 01/22/2014] [Indexed: 11/08/2022] Open
Abstract
Actin filament nucleation and branching by Arp2/3 complex is activated by nucleation-promoting factors (NPFs), whose C-terminal WCA region contains binding sites for actin (W) and Arp2/3 complex (CA). It is debated whether one or two NPFs are required for activation. Here we present evidence in support of the two-NPF model and show that actin plays a crucial role in the interactions of two mammalian NPFs, N-WASP and WAVE2, with Arp2/3 complex. Competition between actin-WCA and glia maturation factor (GMF) for binding to Arp2/3 complex suggests that during activation the first actin monomer binds at the barbed end of Arp2. Based on distance constraints obtained by time-resolved fluorescence resonance energy transfer, we define the relative position of the two actin-WCAs on Arp2/3 complex and propose an atomic model of the 11-subunit transitional complex.
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58
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Actin, actin-related proteins and profilin in diatoms: A comparative genomic analysis. Mar Genomics 2015; 23:133-42. [DOI: 10.1016/j.margen.2015.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 12/24/2022]
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Urbanek AN, Allwood EG, Smith AP, Booth WI, Ayscough KR. Distinct Actin and Lipid Binding Sites in Ysc84 Are Required during Early Stages of Yeast Endocytosis. PLoS One 2015; 10:e0136732. [PMID: 26312755 PMCID: PMC4552428 DOI: 10.1371/journal.pone.0136732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/08/2015] [Indexed: 11/18/2022] Open
Abstract
During endocytosis in S. cerevisiae, actin polymerization is proposed to provide the driving force for invagination against the effects of turgor pressure. In previous studies, Ysc84 was demonstrated to bind actin through a conserved N-terminal domain. However, full length Ysc84 could only bind actin when its C-terminal SH3 domain also bound to the yeast WASP homologue Las17. Live cell-imaging has revealed that Ysc84 localizes to endocytic sites after Las17/WASP but before other known actin binding proteins, suggesting it is likely to function at an early stage of membrane invagination. While there are homologues of Ysc84 in other organisms, including its human homologue SH3yl-1, little is known of its mode of interaction with actin or how this interaction affects actin filament dynamics. Here we identify key residues involved both in Ysc84 actin and lipid binding, and demonstrate that its actin binding activity is negatively regulated by PI(4,5)P2. Ysc84 mutants defective in their lipid or actin-binding interaction were characterized in vivo. The abilities of Ysc84 to bind Las17 through its C-terminal SH3 domain, or to actin and lipid through the N-terminal domain were all shown to be essential in order to rescue temperature sensitive growth in a strain requiring YSC84 expression. Live cell imaging in strains with fluorescently tagged endocytic reporter proteins revealed distinct phenotypes for the mutants indicating the importance of these interactions for regulating key stages of endocytosis.
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Affiliation(s)
- Agnieszka N. Urbanek
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Ellen G. Allwood
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Adam P. Smith
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Wesley I. Booth
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Kathryn R. Ayscough
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
- * E-mail:
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60
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Nishimura M, Fujii T, Hiyoshi H, Makino F, Inoue H, Motooka D, Kodama T, Ohkubo T, Kobayashi Y, Nakamura S, Namba K, Iida T. A repeat unit of Vibrio diarrheal T3S effector subverts cytoskeletal actin homeostasis via binding to interstrand region of actin filaments. Sci Rep 2015; 5:10870. [PMID: 26039684 PMCID: PMC4650670 DOI: 10.1038/srep10870] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 05/05/2015] [Indexed: 11/09/2022] Open
Abstract
A novel bacterial type III secretion effector, VopV, from the enteric pathogen Vibrio parahaemolyticus has been identified as a key factor in pathogenicity due to its interaction with cytoskeletal actin. One of the repeat units in the long repetitive region of VopV, named VopVrep1, functions as an actin-binding module. Despite its importance in pathogenesis, the manner in which the effector binds to actin and the subsequent effects on actin dynamics remain unclear. Here, we report the molecular basis of the VopVrep1/actin interaction. VopVrep1 exists as an unstructured protein in solution but potently and specifically binds filamentous actin (F-actin) and not globular actin (G-actin). The F-actin/VopVrep1 complex was directly visualized at 9.6-Å resolution using electron cryomicroscopy (cryoEM) and helical image reconstitution. The density map revealed the binding site of VopVrep1 at the interface between two actin strands, which is close to the binding site of the bicyclic heptapeptide toxin phalloidin. Consistent with this observation, VopVrep1 alone prevented the depolymerization of F-actin. Overall, VopVrep1 demonstrated unique characteristics in comparison to known actin-binding proteins, but was relatively similar to phalloidin. The phalloidin-like behavior, targeting the interstrand region of actin filaments to stabilize the filament structure, likely contributes to the pathogenicity of V. parahaemolyticus.
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Affiliation(s)
- Mitsuhiro Nishimura
- 1] Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan
| | - Takashi Fujii
- 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hirotaka Hiyoshi
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Fumiaki Makino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hajime Inoue
- Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan
| | - Daisuke Motooka
- 1] Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka Suita, Osaka 565-0871, Japan
| | - Toshio Kodama
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tadayasu Ohkubo
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka Suita, Osaka 565-0871, Japan
| | - Yuji Kobayashi
- Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan
| | - Shota Nakamura
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Keiichi Namba
- 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tetsuya Iida
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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61
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Unconventional actins and actin-binding proteins in human protozoan parasites. Int J Parasitol 2015; 45:435-47. [DOI: 10.1016/j.ijpara.2015.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/19/2014] [Accepted: 01/27/2015] [Indexed: 12/11/2022]
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62
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Kumpula EP, Kursula I. Towards a molecular understanding of the apicomplexan actin motor: on a road to novel targets for malaria remedies? Acta Crystallogr F Struct Biol Commun 2015; 71:500-13. [PMID: 25945702 PMCID: PMC4427158 DOI: 10.1107/s2053230x1500391x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 02/25/2015] [Indexed: 11/10/2022] Open
Abstract
Apicomplexan parasites are the causative agents of notorious human and animal diseases that give rise to considerable human suffering and economic losses worldwide. The most prominent parasites of this phylum are the malaria-causing Plasmodium species, which are widespread in tropical and subtropical regions, and Toxoplasma gondii, which infects one third of the world's population. These parasites share a common form of gliding motility which relies on an actin-myosin motor. The components of this motor and the actin-regulatory proteins in Apicomplexa have unique features compared with all other eukaryotes. This, together with the crucial roles of these proteins, makes them attractive targets for structure-based drug design. In recent years, several structures of glideosome components, in particular of actins and actin regulators from apicomplexan parasites, have been determined, which will hopefully soon allow the creation of a complete molecular picture of the parasite actin-myosin motor and its regulatory machinery. Here, current knowledge of the function of this motor is reviewed from a structural perspective.
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Affiliation(s)
- Esa-Pekka Kumpula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, PO Box 3000, 90014 Oulu, Finland
- Helmholtz Centre for Infection Research, Notkestrasse 85, 22607 Hamburg, Germany
- German Electron Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
| | - Inari Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, PO Box 3000, 90014 Oulu, Finland
- Helmholtz Centre for Infection Research, Notkestrasse 85, 22607 Hamburg, Germany
- German Electron Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
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63
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Deng R, Hao J, Han W, Ni Y, Huang X, Hu Q. Gelsolin regulates proliferation, apoptosis, migration and invasion in human oral carcinoma cells. Oncol Lett 2015; 9:2129-2134. [PMID: 26137026 DOI: 10.3892/ol.2015.3002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 11/28/2014] [Indexed: 12/14/2022] Open
Abstract
Gelsolin (GSN) is one of the most abundant actin-binding proteins, and is involved in several pathological processes, including Alzheimer's disease, cardiac injury and cancer. The aim of the present study was to assess the effect of GSN on the growth and motility of oral squamous cell carcinoma Tca8113 cells. The overexpression vector pcDNA3.1-GSN was transfected into Tca8113 cells and the stable GSN overexpression cell line was identified based on G418 antibiotic selection. The effect of GSN overexpression on the proliferation, apoptosis, migration and invasion of Tca8113 cells was examined using a cell counting kit-8 assay, flow cytometry and Transwell assays. The results revealed that GSN overexpression significantly promoted the cell proliferation and apoptosis of Tca8113 cells. In addition, Transwell assays demonstrated that the migration and invasion abilities of Tca8113 cells were enhanced by GSN overexpression. Therefore, the upregulation of GSN promotes cell growth and motility, indicating that it may perform a vital function in the progression of human oral cancers.
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Affiliation(s)
- Runzhi Deng
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical School, Nanjing University, Nanjing, Jiangsu, P.R. China
| | - Jing Hao
- Central Laboratory of Nanjing Stomatological Hospital, Nanjing, Jiangsu, P.R. China
| | - Wei Han
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical School, Nanjing University, Nanjing, Jiangsu, P.R. China ; Central Laboratory of Nanjing Stomatological Hospital, Nanjing, Jiangsu, P.R. China
| | - Yanhong Ni
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical School, Nanjing University, Nanjing, Jiangsu, P.R. China ; Central Laboratory of Nanjing Stomatological Hospital, Nanjing, Jiangsu, P.R. China
| | - Xiaofeng Huang
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical School, Nanjing University, Nanjing, Jiangsu, P.R. China
| | - Qingang Hu
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Stomatology, Medical School, Nanjing University, Nanjing, Jiangsu, P.R. China
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64
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Lee WL, Grimes JM, Robinson RC. Yersinia effector YopO uses actin as bait to phosphorylate proteins that regulate actin polymerization. Nat Struct Mol Biol 2015; 22:248-55. [PMID: 25664724 DOI: 10.1038/nsmb.2964] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/30/2014] [Indexed: 11/09/2022]
Abstract
Pathogenic Yersinia species evade host immune systems through the injection of Yersinia outer proteins (Yops) into phagocytic cells. One Yop, YopO, also known as YpkA, induces actin-filament disruption, impairing phagocytosis. Here we describe the X-ray structure of Yersinia enterocolitica YopO in complex with actin, which reveals that YopO binds to an actin monomer in a manner that blocks polymerization yet allows the bound actin to interact with host actin-regulating proteins. SILAC-MS and biochemical analyses confirm that actin-polymerization regulators such as VASP, EVL, WASP, gelsolin and the formin diaphanous 1 are directly sequestered and phosphorylated by YopO through formation of ternary complexes with actin. This leads to a model in which YopO at the membrane sequesters actin from polymerization while using the bound actin as bait to recruit, phosphorylate and misregulate host actin-regulating proteins to disrupt phagocytosis.
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Affiliation(s)
- Wei Lin Lee
- 1] Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore. [2] Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jonathan M Grimes
- 1] Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK. [2] Diamond Light Source, Oxfordshire, UK
| | - Robert C Robinson
- 1] Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore. [2] Department of Biochemistry, National University of Singapore, Singapore
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65
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Kremneva E, Makkonen MH, Skwarek-Maruszewska A, Gateva G, Michelot A, Dominguez R, Lappalainen P. Cofilin-2 controls actin filament length in muscle sarcomeres. Dev Cell 2015; 31:215-26. [PMID: 25373779 DOI: 10.1016/j.devcel.2014.09.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/03/2014] [Accepted: 09/03/2014] [Indexed: 01/26/2023]
Abstract
ADF/cofilins drive cytoskeletal dynamics by promoting the disassembly of "aged" ADP-actin filaments. Mammals express several ADF/cofilin isoforms, but their specific biochemical activities and cellular functions have not been studied in detail. Here, we demonstrate that the muscle-specific isoform cofilin-2 promotes actin filament disassembly in sarcomeres to control the precise length of thin filaments in the contractile apparatus. In contrast to other isoforms, cofilin-2 efficiently binds and disassembles both ADP- and ATP/ADP-Pi-actin filaments. We mapped surface-exposed cofilin-2-specific residues required for ATP-actin binding and propose that these residues function as an "actin nucleotide-state sensor" among ADF/cofilins. The results suggest that cofilin-2 evolved specific biochemical and cellular properties that allow it to control actin dynamics in sarcomeres, where filament pointed ends may contain a mixture of ADP- and ATP/ADP-Pi-actin subunits. Our findings also offer a rationale for why cofilin-2 mutations in humans lead to myopathies.
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Affiliation(s)
- Elena Kremneva
- Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
| | - Maarit H Makkonen
- Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
| | | | - Gergana Gateva
- Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
| | - Alphee Michelot
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, 38054 Grenoble, France
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Pekka Lappalainen
- Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland.
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66
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Baker JL, Courtemanche N, Parton DL, McCullagh M, Pollard TD, Voth GA. Electrostatic interactions between the Bni1p Formin FH2 domain and actin influence actin filament nucleation. Structure 2014; 23:68-79. [PMID: 25482541 DOI: 10.1016/j.str.2014.10.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 10/03/2014] [Accepted: 10/21/2014] [Indexed: 10/24/2022]
Abstract
Formins catalyze nucleation and growth of actin filaments. Here, we study the structure and interactions of actin with the FH2 domain of budding yeast formin Bni1p. We built an all-atom model of the formin dimer on an Oda actin filament 7-mer and studied structural relaxation and interprotein interactions by molecular dynamics simulations. These simulations produced a refined model for the FH2 dimer associated with the barbed end of the filament and showed electrostatic interactions between the formin knob and actin target-binding cleft. Mutations of two formin residues contributing to these interactions (R1423N, K1467L, or both) reduced the interaction energies between the proteins, and in coarse-grained simulations, the formin lost more interprotein contacts with an actin dimer than with an actin 7-mer. Biochemical experiments confirmed a strong influence of these mutations on Bni1p-mediated actin filament nucleation, but not elongation, suggesting that different interactions contribute to these two functions of formins.
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Affiliation(s)
- Joseph L Baker
- Department of Chemistry, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; James Franck Institute, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; Computation Institute, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA
| | - Naomi Courtemanche
- Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208103, New Haven, CT 06520-8103, USA
| | - Daniel L Parton
- Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Martin McCullagh
- Department of Chemistry, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; James Franck Institute, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; Computation Institute, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA
| | - Thomas D Pollard
- Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208103, New Haven, CT 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, P.O. Box 208103, New Haven, CT 06520-8103, USA; Department of Cell Biology, Yale University, P.O. Box 208103, New Haven, CT 06520-8103, USA
| | - Gregory A Voth
- Department of Chemistry, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; James Franck Institute, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA; Computation Institute, The University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA.
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Udompetcharaporn A, Junkunlo K, Senapin S, Roytrakul S, Flegel TW, Sritunyalucksana K. Identification and characterization of a QM protein as a possible peptidoglycan recognition protein (PGRP) from the giant tiger shrimp Penaeus monodon. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 46:146-154. [PMID: 24736204 DOI: 10.1016/j.dci.2014.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 04/03/2014] [Accepted: 04/06/2014] [Indexed: 06/03/2023]
Abstract
In an attempt to identify a peptidoglycan recognition protein (PGRP) in Penaeus (Penaeus) monodon, in vitro pull-down binding assays were used between shrimp proteins and purified peptidoglycan (PG). By gel electrophoresis and mass spectrometry followed by Mascot program analysis, proteins from shrimp hemocyte peripheral membrane proteins showed significant homology to records for a QM protein, actin and prophenoloxidase 2 precursor (proPO2), while proteins from cell-free plasma showed significant homology to records for a vitellogenin, a fibrinogen related protein (FREP) and a C-type lectin. Due to time and resource limitations, specific binding to PG was examined only for recombinant PmQM protein and PmLec that were synthesized based on sequences reported in the Genbank database (accession numbers FJ766846 and DQ078266, respectively). An in vitro assay revealed that hemocytes would bind with and encapsulate agarose beads coated with recombinant PmQM (rPmQM) or rPmLec and that melanization followed 2h post-encapsulation. ELISA tests confirmed specific binding of rPmQM protein to PG. This is the first time that PmQM has been reported as a potential PGRP in shrimp or any other crustacean. The two other potential PGRP identified (FREP and the vitellin-like protein present in male P. monodon, unlike other vitellin subunits) should also be expressed heterologously and tested for their ability to activate shrimp hemocytes.
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Affiliation(s)
- Attasit Udompetcharaporn
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand
| | - Kingkamon Junkunlo
- Department of Comparative Physiology, Evolutionary Biology Center (EBC), Uppsala University, Norbyvägen 18A, Uppsala, Sweden
| | - Saengchan Senapin
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand
| | - Sittiruk Roytrakul
- Proteomics Research Laboratory, Genome Institute, National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Pathumthani 12120, Thailand
| | - Timothy W Flegel
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand
| | - Kallaya Sritunyalucksana
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand; Shrimp-Virus Interaction Laboratory (ASVI), National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Rama VI Rd., Bangkok 10400, Thailand.
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68
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Edwards M, Zwolak A, Schafer DA, Sept D, Dominguez R, Cooper JA. Capping protein regulators fine-tune actin assembly dynamics. Nat Rev Mol Cell Biol 2014; 15:677-89. [PMID: 25207437 DOI: 10.1038/nrm3869] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Capping protein (CP) binds the fast growing barbed end of the actin filament and regulates actin assembly by blocking the addition and loss of actin subunits. Recent studies provide new insights into how CP and barbed-end capping are regulated. Filament elongation factors, such as formins and ENA/VASP (enabled/vasodilator-stimulated phosphoprotein), indirectly regulate CP by competing with CP for binding to the barbed end, whereas other molecules, including V-1 and phospholipids, directly bind to CP and sterically block its interaction with the filament. In addition, a diverse and unrelated group of proteins interact with CP through a conserved 'capping protein interaction' (CPI) motif. These proteins, including CARMIL (capping protein, ARP2/3 and myosin I linker), CD2AP (CD2-associated protein) and the WASH (WASP and SCAR homologue) complex subunit FAM21, recruit CP to specific subcellular locations and modulate its actin-capping activity via allosteric effects.
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Affiliation(s)
- Marc Edwards
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110, USA
| | - Adam Zwolak
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Dorothy A Schafer
- Departments of Biology and Cell Biology, University of Virginia, Charlottesville, Virginia 22904, USA
| | - David Sept
- Department of Biomedical Engineering and Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - John A Cooper
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri 63110, USA
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Pereira JH, Petchprayoon C, Hoepker AC, Moriarty NW, Fink SJ, Cecere G, Paterson I, Adams PD, Marriott G. Structural and biochemical studies of actin in complex with synthetic macrolide tail analogues. ChemMedChem 2014; 9:2286-93. [PMID: 25047814 DOI: 10.1002/cmdc.201402150] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Indexed: 11/12/2022]
Abstract
The actin filament-binding and filament-severing activities of the aplyronine, kabiramide, and reidispongiolide families of marine macrolides are located within the hydrophobic tail region of the molecule. Two synthetic tail analogues of aplyronine C (SF-01 and GC-04) are shown to bind to G-actin with dissociation constants of (285±33) and (132±13) nM, respectively. The crystal structures of actin complexes with GC-04, SF-01, and kabiramide C reveal a conserved mode of tail binding within the cleft that forms between subdomains (SD) 1 and 3. Our studies support the view that filament severing is brought about by specific binding of the tail region to the SD1/SD3 cleft on the upper protomer, which displaces loop-D from the lower protomer on the same half-filament. With previous studies showing that the GC-04 analogue can sever actin filaments, it is argued that the shorter complex lifetime of tail analogues with F-actin would make them more effective at severing filaments compared with plasma gelsolin. Structure-based analyses are used to suggest more reactive or targetable forms of GC-04 and SF-01, which may serve to boost the capacity of the serum actin scavenging system, to generate antibody conjugates against tumor cell antigens, and to decrease sputum viscosity in children with cystic fibrosis.
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Affiliation(s)
- Jose H Pereira
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (USA)
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70
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Vahokoski J, Bhargav SP, Desfosses A, Andreadaki M, Kumpula EP, Martinez SM, Ignatev A, Lepper S, Frischknecht F, Sidén-Kiamos I, Sachse C, Kursula I. Structural differences explain diverse functions of Plasmodium actins. PLoS Pathog 2014; 10:e1004091. [PMID: 24743229 PMCID: PMC3990709 DOI: 10.1371/journal.ppat.1004091] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 03/11/2014] [Indexed: 11/18/2022] Open
Abstract
Actins are highly conserved proteins and key players in central processes in all eukaryotic cells. The two actins of the malaria parasite are among the most divergent eukaryotic actins and also differ from each other more than isoforms in any other species. Microfilaments have not been directly observed in Plasmodium and are presumed to be short and highly dynamic. We show that actin I cannot complement actin II in male gametogenesis, suggesting critical structural differences. Cryo-EM reveals that Plasmodium actin I has a unique filament structure, whereas actin II filaments resemble canonical F-actin. Both Plasmodium actins hydrolyze ATP more efficiently than α-actin, and unlike any other actin, both parasite actins rapidly form short oligomers induced by ADP. Crystal structures of both isoforms pinpoint several structural changes in the monomers causing the unique polymerization properties. Inserting the canonical D-loop to Plasmodium actin I leads to the formation of long filaments in vitro. In vivo, this chimera restores gametogenesis in parasites lacking actin II, suggesting that stable filaments are required for exflagellation. Together, these data underline the divergence of eukaryotic actins and demonstrate how structural differences in the monomers translate into filaments with different properties, implying that even eukaryotic actins have faced different evolutionary pressures and followed different paths for developing their polymerization properties. Malaria parasites have two actin isoforms, which are among the most divergent within the actin family that comprises highly conserved proteins, essential in all eukaryotic cells. In Plasmodium, actin is indispensable for motility and, thus, the infectivity of the deadly parasite. Yet, actin filaments have not been observed in vivo in these pathogens. Here, we show that the two Plasmodium actins differ from each other in both monomeric and filamentous form and that actin I cannot replace actin II during male gametogenesis. Whereas the major isoform actin I cannot form stable filaments alone, the mosquito-stage-specific actin II readily forms long filaments that have dimensions similar to canonical actins. A chimeric actin I mutant that forms long filaments in vitro also rescues gametogenesis in parasites lacking actin II. Both Plasmodium actins rapidly hydrolyze ATP and form short oligomers in the presence of ADP, which is a fundamental difference to all other actins characterized to date. Structural and functional differences in the two Plasmodium actin isoforms compared both to each other and to canonical actins reveal how the polymerization properties of eukaryotic actins have evolved along different avenues.
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Affiliation(s)
- Juha Vahokoski
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - Ambroise Desfosses
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
| | - Maria Andreadaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas, Heraklion, Crete, Greece
| | - Esa-Pekka Kumpula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology; Helmholtz Centre for Infection Research and German Electron Synchrotron, Hamburg, Germany
| | | | - Alexander Ignatev
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Simone Lepper
- Parasitology – Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
| | - Friedrich Frischknecht
- Parasitology – Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
| | - Inga Sidén-Kiamos
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas, Heraklion, Crete, Greece
| | - Carsten Sachse
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
| | - Inari Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology; Helmholtz Centre for Infection Research and German Electron Synchrotron, Hamburg, Germany
- * E-mail:
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71
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Thompson PM, Tolbert CE, Shen K, Kota P, Palmer SM, Plevock KM, Orlova A, Galkin VE, Burridge K, Egelman EH, Dokholyan NV, Superfine R, Campbell SL. Identification of an actin binding surface on vinculin that mediates mechanical cell and focal adhesion properties. Structure 2014; 22:697-706. [PMID: 24685146 DOI: 10.1016/j.str.2014.03.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/04/2014] [Accepted: 03/04/2014] [Indexed: 11/30/2022]
Abstract
Vinculin, a cytoskeletal scaffold protein essential for embryogenesis and cardiovascular function, localizes to focal adhesions and adherens junctions, connecting cell surface receptors to the actin cytoskeleton. While vinculin interacts with many adhesion proteins, its interaction with filamentous actin regulates cell morphology, motility, and mechanotransduction. Disruption of this interaction lowers cell traction forces and enhances actin flow rates. Although a model for the vinculin:actin complex exists, we recently identified actin-binding deficient mutants of vinculin outside sites predicted to bind actin and developed an alternative model to better define this actin-binding surface, using negative-stain electron microscopy (EM), discrete molecular dynamics, and mutagenesis. Actin-binding deficient vinculin variants expressed in vinculin knockout fibroblasts fail to rescue cell-spreading defects and reduce cellular response to external force. These findings highlight the importance of this actin-binding surface and provide the molecular basis for elucidating additional roles of this interaction, including actin-induced conformational changes that promote actin bundling.
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Affiliation(s)
- Peter M Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Caitlin E Tolbert
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kai Shen
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Pradeep Kota
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sean M Palmer
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Karen M Plevock
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Vitold E Galkin
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Keith Burridge
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Richard Superfine
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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72
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Perissinotti PP, Ethington EG, Cribbs L, Koob MD, Martin J, Piedras-Rentería ES. Down-regulation of endogenous KLHL1 decreases voltage-gated calcium current density. Cell Calcium 2014; 55:269-80. [PMID: 24703904 DOI: 10.1016/j.ceca.2014.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 10/25/2022]
Abstract
The actin-binding protein Kelch-like 1 (KLHL1) can modulate voltage-gated calcium channels in vitro. KLHL1 interacts with actin and with the pore-forming subunits of Cav2.1 and CaV3.2 calcium channels, resulting in up-regulation of P/Q and T-type current density. Here we tested whether endogenous KLHL1 modulates voltage gated calcium currents in cultured hippocampal neurons by down-regulating the expression of KLHL1 via adenoviral delivery of shRNA targeted against KLHL1 (shKLHL1). Control adenoviruses did not affect any of the neuronal properties measured, yet down-regulation of KLHL1 resulted in HVA current densities ~68% smaller and LVA current densities 44% smaller than uninfected controls, with a concomitant reduction in α(1A) and α(1H) protein levels. Biophysical analysis and western blot experiments suggest Ca(V)3.1 and 3.3 currents are also present in shKLHL1-infected neurons. Synapsin I levels, miniature postsynaptic current frequency, and excitatory and inhibitory synapse number were reduced in KLHL1 knockdown. This study corroborates the physiological role of KLHL1 as a calcium channel modulator and demonstrates a novel, presynaptic role.
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Affiliation(s)
- Paula P Perissinotti
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Elizabeth G Ethington
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Leanne Cribbs
- Office of Research Services, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Michael D Koob
- Institute for Translational Neuroscience, Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jody Martin
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA; Neuroscience Institute, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Erika S Piedras-Rentería
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA; Neuroscience Institute, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA.
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73
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Jensen MH, Morris EJ, Gallant CM, Morgan KG, Weitz DA, Moore JR. Mechanism of calponin stabilization of cross-linked actin networks. Biophys J 2014; 106:793-800. [PMID: 24559982 PMCID: PMC3944828 DOI: 10.1016/j.bpj.2013.12.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/11/2013] [Accepted: 12/23/2013] [Indexed: 01/06/2023] Open
Abstract
The actin-binding protein calponin has been previously implicated in actin cytoskeletal regulation and is thought to act as an actin stabilizer, but the mechanism of its function is poorly understood. To investigate this underlying physical mechanism, we studied an in vitro model system of cross-linked actin using bulk rheology. Networks with basic calponin exhibited a delayed onset of strain stiffening (10.0% without calponin, 14.9% with calponin) and were able to withstand a higher maximal strain before failing (35% without calponin, 56% with calponin). Using fluorescence microscopy to study the mechanics of single actin filaments, we found that calponin increased the flexibility of actin filaments, evident as a decrease in persistence length from 17.6 μm without to 7.7 μm with calponin. Our data are consistent with current models of affine strain behavior in semiflexible polymer networks, and suggest that calponin stabilization of actin networks can be explained purely by changes in single-filament mechanics. We propose a model in which calponin stabilizes actin networks against shear through a reduction of persistence length of individual filaments.
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Affiliation(s)
- Mikkel Herholdt Jensen
- Department of Physiology and Biophysics, Boston University, Boston, Massachusetts; School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Eliza J Morris
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Cynthia M Gallant
- Department of Health Sciences, Boston University, Boston, Massachusetts
| | - Kathleen G Morgan
- Department of Health Sciences, Boston University, Boston, Massachusetts
| | - David A Weitz
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University, Boston, Massachusetts.
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74
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Speeckaert MM, Speeckaert R, van Geel N, Delanghe JR. Vitamin D binding protein: a multifunctional protein of clinical importance. Adv Clin Chem 2014; 63:1-57. [PMID: 24783350 DOI: 10.1016/b978-0-12-800094-6.00001-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Since the discovery of group-specific component and its polymorphism by Hirschfeld in 1959, research has put spotlight on this multifunctional transport protein (vitamin D binding protein, DBP). Besides the transport of vitamin D metabolites, DBP is a plasma glycoprotein with many important functions, including sequestration of actin, modulation of immune and inflammatory responses, binding of fatty acids, and control of bone development. A considerable DBP polymorphism has been described with a specific allele distribution in different geographic area. Multiple studies have shed light on the interesting relationship between polymorphisms of the DBP gene and the susceptibility to diseases. In this review, we give an overview of the multifunctional character of DBP and describe the clinical importance of DBP and its polymorphisms. Finally, we discuss the possibilities to use DBP as a novel therapeutic agent.
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75
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Tsuge H, Tsurumura T. Reaction Mechanism of Mono-ADP-Ribosyltransferase Based on Structures of the Complex of Enzyme and Substrate Protein. Curr Top Microbiol Immunol 2014; 384:69-87. [PMID: 24990621 DOI: 10.1007/82_2014_415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mono-ADP-ribosylation is a post-translational protein modification catalyzed by bacterial toxins and exoenzymes that function as ADP-ribosyltransferases. Despite the importance of this modification, the reaction mechanism remains poorly understood due to a lack of information on the crystal structure of these enzymes in complex with a substrate protein. Recently, the structures of two such complexes became available, which shed new light on the mechanisms of mono-ADP-ribosylation. In this review, we consider the reaction mechanism based on the structures of ADP-ribosyltransferases in complex with a substrate protein.
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Affiliation(s)
- Hideaki Tsuge
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, 603-8555, Japan,
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76
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Chen CK, Benchaar SA, Phan M, Grintsevich EE, Loo RRO, Loo JA, Reisler E. Cofilin-induced changes in F-actin detected via cross-linking with benzophenone-4-maleimide. Biochemistry 2013; 52:5503-9. [PMID: 23862734 DOI: 10.1021/bi400715z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cofilin is a member of the actin depolymerizing factor (ADF)/cofilin family of proteins. It plays a key role in actin dynamics by promoting disassembly and assembly of actin filaments. Upon its binding, cofilin has been shown to bridge two adjacent protomers in filamentous actin (F-actin) and promote the displacement and disordering of subdomain 2 of actin. Here, we present evidence for cofilin promoting a new structural change in the actin filament, as detected via a switch in cross-linking sites. Benzophenone-4-maleimide, which normally forms intramolecular cross-linking in F-actin, cross-links F-actin intermolecularly upon cofilin binding. We mapped the cross-linking sites and found that in the absence of cofilin intramolecular cross-linking occurred between residues Cys374 and Asp11. In contrast, cofilin shifts the cross-linking by this reagent to intermolecular, between residue Cys374, located within subdomain 1 of the upper protomer, and Met44, located in subdomain 2 of the lower protomer. The intermolecular cross-linking of F-actin slows the rate of cofilin dissociation from the filaments and decreases the effect of ionic strength on cofilin-actin binding. These results are consistent with a significant role of filament flexibility in cofilin-actin interactions.
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Affiliation(s)
- Christine K Chen
- Department of Chemistry and Biochemistry, Molecular Biology Institute and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
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77
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Structural basis for regulation of Arp2/3 complex by GMF. Nat Struct Mol Biol 2013; 20:1062-8. [PMID: 23893131 PMCID: PMC3766443 DOI: 10.1038/nsmb.2628] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 06/05/2013] [Indexed: 01/15/2023]
Abstract
Arp2/3 complex mediates formation of complex cellular structures such as lamellapodia by nucleating branched actin filaments. Arp2/3 complex activity is precisely controlled by more than a dozen regulators, yet the structural mechanism by which regulators interact with the complex is unknown. GMF is a recently discovered regulator of Arp2/3 complex that can inhibit nucleation and dissemble branches. We solved the structure of the 240 kDa complex of Mus musculus GMF and Bos taurus Arp2/3 and found GMF binds to the barbed end of Arp2, overlapping with the proposed binding site of WASP family proteins. The structure suggests GMF can bind branch junctions like cofilin binds filament sides, consistent with a modified cofilin-like mechanism for debranching by GMF. The GMF-Arp2 interface reveals how the ADF-H actin-binding domain in GMF is exploited to specifically recognize Arp2/3 complex and not actin.
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78
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Beck MR, Dixon RDS, Goicoechea SM, Murphy GS, Brungardt JG, Beam MT, Srinath P, Patel J, Mohiuddin J, Otey CA, Campbell SL. Structure and function of palladin's actin binding domain. J Mol Biol 2013; 425:3325-37. [PMID: 23806659 DOI: 10.1016/j.jmb.2013.06.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 06/03/2013] [Accepted: 06/11/2013] [Indexed: 11/28/2022]
Abstract
Here, we report the NMR structure of the actin-binding domain contained in the cell adhesion protein palladin. Previously, we demonstrated that one of the immunoglobulin domains of palladin (Ig3) is both necessary and sufficient for direct filamentous actin binding in vitro. In this study, we identify two basic patches on opposite faces of Ig3 that are critical for actin binding and cross-linking. Sedimentation equilibrium assays indicate that the Ig3 domain of palladin does not self-associate. These combined data are consistent with an actin cross-linking mechanism that involves concurrent attachment of two actin filaments by a single palladin molecule by an electrostatic mechanism. Palladin mutations that disrupt actin binding show altered cellular distributions and morphology of actin in cells, revealing a functional requirement for the interaction between palladin and actin in vivo.
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Affiliation(s)
- Moriah R Beck
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, 120 Mason Farm Road, Chapel Hill, NC 27599, USA.
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79
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Chen X, Ni F, Tian X, Kondrashkina E, Wang Q, Ma J. Structural basis of actin filament nucleation by tandem W domains. Cell Rep 2013; 3:1910-20. [PMID: 23727244 DOI: 10.1016/j.celrep.2013.04.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 03/23/2013] [Accepted: 04/26/2013] [Indexed: 11/17/2022] Open
Abstract
Spontaneous nucleation of actin is very inefficient in cells. To overcome this barrier, cells have evolved a set of actin filament nucleators to promote rapid nucleation and polymerization in response to specific stimuli. However, the molecular mechanism of actin nucleation remains poorly understood. This is hindered largely by the fact that actin nucleus, once formed, rapidly polymerizes into filament, thus making it impossible to capture stable multisubunit actin nucleus. Here, we report an effective double-mutant strategy to stabilize actin nucleus by preventing further polymerization. Employing this strategy, we solved the crystal structure of AMPPNP-actin in complex with the first two tandem W domains of Cordon-bleu (Cobl), a potent actin filament nucleator. Further sequence comparison and functional studies suggest that the nucleation mechanism of Cobl is probably shared by the p53 cofactor JMY, but not Spire. Moreover, the double-mutant strategy opens the way for atomic mechanistic study of actin nucleation and polymerization.
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Affiliation(s)
- Xiaorui Chen
- Graduate Program of Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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80
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Vinculin and metavinculin: Oligomerization and interactions with F-actin. FEBS Lett 2013; 587:1220-9. [DOI: 10.1016/j.febslet.2013.02.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 02/20/2013] [Accepted: 02/20/2013] [Indexed: 01/09/2023]
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81
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Travers T, Shao H, Wells A, Camacho C. Modeling the assembly of the multiple domains of α-actinin-4 and its role in actin cross-linking. Biophys J 2013; 104:705-15. [PMID: 23442921 PMCID: PMC3566466 DOI: 10.1016/j.bpj.2012.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/04/2012] [Accepted: 12/05/2012] [Indexed: 12/30/2022] Open
Abstract
The assembly of proteins into multidomain complexes is critical for their function. In eukaryotic nonmuscle cells, regulation of the homodimeric actin cross-linking protein α-actinin-4 (ACTN4) during cell migration involves signaling receptors with intrinsic tyrosine kinase activity, yet the underlying molecular mechanisms are poorly understood. As a first step to address the latter, we validate here an atomic model for the ACTN4 end region, which corresponds to a ternary complex between the N-terminal actin-binding domain (ABD) and an adjacent helical neck region of one monomer, and the C-terminal calmodulin-like domain of the opposite antiparallel monomer. Mutagenesis experiments designed to disrupt this ternary complex confirm that its formation reduces binding to F-actin. Molecular dynamics simulations show that the phosphomimic mutation Y265E increases actin binding by breaking several interactions that tether the two calponin homology domains into a closed ABD conformation. Simulations also show a disorder-to-order transition in the double phosphomimic mutant Y4E/Y31E of the 45-residue ACTN4 N-terminal region, which can inhibit actin binding by latching both calponin homology domains more tightly. Collectively, these studies provide a starting point for understanding the role of external cues in regulating ACTN4, with different phenotypes resulting from changes in the multidomain assembly of the protein.
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Affiliation(s)
- Timothy Travers
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Hanshuang Shao
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Alan Wells
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Carlos J. Camacho
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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82
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83
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Gayathri P, Fujii T, Møller-Jensen J, van den Ent F, Namba K, Löwe J. A bipolar spindle of antiparallel ParM filaments drives bacterial plasmid segregation. Science 2012; 338:1334-7. [PMID: 23112295 DOI: 10.1126/science.1229091] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To ensure their stable inheritance by daughter cells during cell division, bacterial low-copy-number plasmids make simple DNA segregating machines that use an elongating protein filament between sister plasmids. In the ParMRC system of the Escherichia coli R1 plasmid, ParM, an actinlike protein, forms the spindle between ParRC complexes on sister plasmids. By using a combination of structural work and total internal reflection fluorescence microscopy, we show that ParRC bound and could accelerate growth at only one end of polar ParM filaments, mechanistically resembling eukaryotic formins. The architecture of ParM filaments enabled two ParRC-bound filaments to associate in an antiparallel orientation, forming a bipolar spindle. The spindle elongated as a bundle of at least two antiparallel filaments, thereby pushing two plasmid clusters toward the poles.
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Affiliation(s)
- P Gayathri
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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84
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Durer ZAO, Kudryashov DS, Sawaya MR, Altenbach C, Hubbell W, Reisler E. Structural states and dynamics of the D-loop in actin. Biophys J 2012; 103:930-9. [PMID: 23009842 PMCID: PMC3433612 DOI: 10.1016/j.bpj.2012.07.030] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/09/2012] [Accepted: 07/13/2012] [Indexed: 01/07/2023] Open
Abstract
Conformational changes induced by ATP hydrolysis on actin are involved in the regulation of complex actin networks. Previous structural and biochemical data implicate the DNase I binding loop (D-loop) of actin in such nucleotide-dependent changes. Here, we investigated the structural and conformational states of the D-loop (in solution) using cysteine scanning mutagenesis and site-directed labeling. The reactivity of D-loop cysteine mutants toward acrylodan and the mobility of spin labels on these mutants do not show patterns of an α-helical structure in monomeric and filamentous actin, irrespective of the bound nucleotide. Upon transition from monomeric to filamentous actin, acrylodan emission spectra and electron paramagnetic resonance line shapes of labeled mutants are blue-shifted and more immobilized, respectively, with the central residues (residues 43-47) showing the most drastic changes. Moreover, complex electron paramagnetic resonance line shapes of spin-labeled mutants suggest several conformational states of the D-loop. Together with a new (to our knowledge) actin crystal structure that reveals the D-loop in a unique hairpin conformation, our data suggest that the D-loop equilibrates in F-actin among different conformational states irrespective of the nucleotide state of actin.
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Affiliation(s)
- Zeynep A Oztug Durer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA.
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85
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Shoji K, Ohashi K, Sampei K, Oikawa M, Mizuno K. Cytochalasin D acts as an inhibitor of the actin-cofilin interaction. Biochem Biophys Res Commun 2012; 424:52-7. [PMID: 22728040 DOI: 10.1016/j.bbrc.2012.06.063] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 06/14/2012] [Indexed: 11/25/2022]
Abstract
Cofilin, a key regulator of actin filament dynamics, binds to G- and F-actin and promotes actin filament turnover by stimulating depolymerization and severance of actin filaments. In this study, cytochalasin D (CytoD), a widely used inhibitor of actin dynamics, was found to act as an inhibitor of the G-actin-cofilin interaction by binding to G-actin. CytoD also inhibited the binding of cofilin to F-actin and decreased the rate of both actin polymerization and depolymerization in living cells. CytoD altered cellular F-actin organization but did not induce net actin polymerization or depolymerization. These results suggest that CytoD inhibits actin filament dynamics in cells via multiple mechanisms, including the well-known barbed-end capping mechanism and as shown in this study, the inhibition of G- and F-actin binding to cofilin.
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Affiliation(s)
- Kazuyasu Shoji
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
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86
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Jensen MH, Watt J, Hodgkinson J, Gallant C, Appel S, El-Mezgueldi M, Angelini TE, Morgan KG, Lehman W, Moore JR. Effects of basic calponin on the flexural mechanics and stability of F-actin. Cytoskeleton (Hoboken) 2012; 69:49-58. [PMID: 22135101 PMCID: PMC3355516 DOI: 10.1002/cm.20548] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 10/28/2011] [Accepted: 11/14/2011] [Indexed: 01/12/2023]
Abstract
The cellular actin cytoskeleton plays a central role in the ability of cells to properly sense, propagate, and respond to external stresses and other mechanical stimuli. Calponin, an actin-binding protein found both in muscle and non-muscle cells, has been implicated in actin cytoskeletal organization and regulation. In this work, we studied the mechanical and structural interaction of actin with basic calponin, a differentiation marker in smooth muscle cells, on a single filament level. We imaged fluorescently labeled thermally fluctuating actin filaments and found that at moderate calponin binding densities, actin filaments were more flexible, evident as a reduction in persistence length from 8.0 to 5.8 μm. When calponin-decorated actin filaments were subjected to shear, we observed a marked reduction of filament lengths after decoration with calponin, which we argue was due to shear-induced filament rupture rather than depolymerization. This increased shear susceptibility was exacerbated with calponin concentration. Cryo-electron microscopy results confirmed previously published negative stain electron microscopy results and suggested alterations in actin involving actin subdomain 2. A weakening of F-actin intermolecular association is discussed as the underlying cause of the observed mechanical perturbations.
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Affiliation(s)
- Mikkel Herholdt Jensen
- Boston University, School of Medicine, Boston, MA
- Boston University, Department of Physics, Boston, MA
| | - James Watt
- Boston University, School of Medicine, Boston, MA
| | - Julie Hodgkinson
- Medical School Hannover, Department of Molecular and Cell Physiology, Hannover, Germany
| | - Cynthia Gallant
- Boston University, Department of Health Sciences, Boston, MA
| | - Sarah Appel
- Boston University, Department of Health Sciences, Boston, MA
| | | | - Thomas E. Angelini
- University of Florida, Department of Mechanical and Aerospace Engineering, Gainesville, FL
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87
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Myosin binding surface on actin probed by hydroxyl radical footprinting and site-directed labels. J Mol Biol 2011; 414:204-16. [PMID: 21986200 DOI: 10.1016/j.jmb.2011.09.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/09/2011] [Accepted: 09/20/2011] [Indexed: 11/22/2022]
Abstract
Actin and myosin are the two main proteins required for cell motility and muscle contraction. The structure of their strongly bound complex-rigor state-is a key for delineating the functional mechanism of actomyosin motor. Current knowledge of that complex is based on models obtained from the docking of known atomic structures of actin and myosin subfragment 1 (S1; the head and neck region of myosin) into low-resolution electron microscopy electron density maps, which precludes atomic- or side-chain-level information. Here, we use radiolytic protein footprinting for global mapping of sites across the actin molecules that are impacted directly or allosterically by myosin binding to actin filaments. Fluorescence and electron paramagnetic resonance spectroscopies and cysteine actin mutants are used for independent, residue-specific probing of S1 effects on two structural elements of actin. We identify actin residue candidates involved in S1 binding and provide experimental evidence to discriminate between the regions of hydrophobic and electrostatic interactions. Focusing on the role of the DNase I binding loop (D-loop) and the W-loop residues of actin in their interactions with S1, we found that the emission properties of acrylodan and the mobility of electron paramagnetic resonance spin labels attached to cysteine mutants of these residues change strongly and in a residue-specific manner upon S1 binding, consistent with the recently proposed direct contacts of these loops with S1. As documented in this study, the direct and indirect changes on actin induced by myosin are more extensive than known until now and attest to the importance of actin dynamics to actomyosin function.
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88
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Wen KK, McKane M, Stokasimov E, Rubenstein PA. Mutant profilin suppresses mutant actin-dependent mitochondrial phenotype in Saccharomyces cerevisiae. J Biol Chem 2011; 286:41745-41757. [PMID: 21956104 DOI: 10.1074/jbc.m110.217661] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the Saccharomyces cerevisiae actin-profilin interface, Ala(167) of the actin barbed end W-loop and His(372) near the C terminus form a clamp around a profilin segment containing residue Arg(81) and Tyr(79). Modeling suggests that altering steric packing in this interface regulates actin activity. An actin A167E mutation could increase interface crowding and alter actin regulation, and A167E does cause growth defects and mitochondrial dysfunction. We assessed whether a profilin Y79S mutation with its decreased mass could compensate for actin A167E crowding and rescue the mutant phenotype. Y79S profilin alone caused no growth defect in WT actin cells under standard conditions in rich medium and rescued the mitochondrial phenotype resulting from both the A167E and H372R actin mutations in vivo consistent with our model. Rescue did not result from effects of profilin on actin nucleotide exchange or direct effects of profilin on actin polymerization. Polymerization of A167E actin was less stimulated by formin Bni1 FH1-FH2 fragment than was WT actin. Addition of WT profilin to mixtures of A167E actin and formin fragment significantly altered polymerization kinetics from hyperbolic to a decidedly more sigmoidal behavior. Substitution of Y79S profilin in this system produced A167E behavior nearly identical to that of WT actin. A167E actin caused more dynamic actin cable behavior in vivo than observed with WT actin. Introduction of Y79S restored cable movement to a more normal phenotype. Our studies implicate the importance of the actin-profilin interface for formin-dependent actin and point to the involvement of formin and profilin in the maintenance of mitochondrial integrity and function.
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Affiliation(s)
- Kuo-Kuang Wen
- Department of Biochemistry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242
| | - Melissa McKane
- Department of Biochemistry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242
| | - Ema Stokasimov
- Department of Biochemistry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242
| | - Peter A Rubenstein
- Department of Biochemistry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242.
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89
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Poukkula M, Kremneva E, Serlachius M, Lappalainen P. Actin-depolymerizing factor homology domain: a conserved fold performing diverse roles in cytoskeletal dynamics. Cytoskeleton (Hoboken) 2011; 68:471-90. [PMID: 21850706 DOI: 10.1002/cm.20530] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/29/2011] [Accepted: 08/05/2011] [Indexed: 11/09/2022]
Abstract
Actin filaments form contractile and protrusive structures that play central roles in many processes such as cell migration, morphogenesis, endocytosis, and cytokinesis. During these processes, the dynamics of the actin filaments are precisely regulated by a large array of actin-binding proteins. The actin-depolymerizing factor homology (ADF-H) domain is a structurally conserved protein motif, which promotes cytoskeletal dynamics by interacting with monomeric and/or filamentous actin, and with the Arp2/3 complex. Despite their structural homology, the five classes of ADF-H domain proteins display distinct biochemical activities and cellular roles, only parts of which are currently understood. ADF/cofilin promotes disassembly of aged actin filaments, whereas twinfilin inhibits actin filament assembly via sequestering actin monomers and interacting with filament barbed ends. GMF does not interact with actin, but instead binds Arp2/3 complex and promotes dissociation of Arp2/3-mediated filament branches. Abp1 and drebrin are multidomain proteins that interact with actin filaments and regulate the activities of other proteins during various actin-dependent processes. The exact function of coactosin is currently incompletely understood. In this review article, we discuss the biochemical functions, cellular roles, and regulation of the five groups of ADF-H domain proteins.
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Affiliation(s)
- Minna Poukkula
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Finland
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90
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Abstract
Actin is the most abundant protein in most eukaryotic cells. It is highly conserved and participates in more protein-protein interactions than any known protein. These properties, along with its ability to transition between monomeric (G-actin) and filamentous (F-actin) states under the control of nucleotide hydrolysis, ions, and a large number of actin-binding proteins, make actin a critical player in many cellular functions, ranging from cell motility and the maintenance of cell shape and polarity to the regulation of transcription. Moreover, the interaction of filamentous actin with myosin forms the basis of muscle contraction. Owing to its central role in the cell, the actin cytoskeleton is also disrupted or taken over by numerous pathogens. Here we review structures of G-actin and F-actin and discuss some of the interactions that control the polymerization and disassembly of actin.
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Affiliation(s)
- Roberto Dominguez
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6085, USA.
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91
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Production of human β-actin and a mutant using a bacterial expression system with a cold shock vector. Protein Expr Purif 2011; 78:1-5. [DOI: 10.1016/j.pep.2010.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 09/04/2010] [Accepted: 09/12/2010] [Indexed: 11/21/2022]
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92
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Jansen S, Collins A, Yang C, Rebowski G, Svitkina T, Dominguez R. Mechanism of actin filament bundling by fascin. J Biol Chem 2011; 286:30087-96. [PMID: 21685497 DOI: 10.1074/jbc.m111.251439] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Fascin is the main actin filament bundling protein in filopodia. Because of the important role filopodia play in cell migration, fascin is emerging as a major target for cancer drug discovery. However, an understanding of the mechanism of bundle formation by fascin is critically lacking. Fascin consists of four β-trefoil domains. Here, we show that fascin contains two major actin-binding sites, coinciding with regions of high sequence conservation in β-trefoil domains 1 and 3. The site in β-trefoil-1 is located near the binding site of the fascin inhibitor macroketone and comprises residue Ser-39, whose phosphorylation by protein kinase C down-regulates actin bundling and formation of filopodia. The site in β-trefoil-3 is related by pseudo-2-fold symmetry to that in β-trefoil-1. The two sites are ∼5 nm apart, resulting in a distance between actin filaments in the bundle of ∼8.1 nm. Residue mutations in both sites disrupt bundle formation in vitro as assessed by co-sedimentation with actin and electron microscopy and severely impair formation of filopodia in cells as determined by rescue experiments in fascin-depleted cells. Mutations of other areas of the fascin surface also affect actin bundling and formation of filopodia albeit to a lesser extent, suggesting that, in addition to the two major actin-binding sites, fascin makes secondary contacts with other filaments in the bundle. In a high resolution crystal structure of fascin, molecules of glycerol and polyethylene glycol are bound in pockets located within the two major actin-binding sites. These molecules could guide the rational design of new anticancer fascin inhibitors.
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Affiliation(s)
- Silvia Jansen
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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93
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Hong F, Haldeman BD, Jackson D, Carter M, Baker JE, Cremo CR. Biochemistry of smooth muscle myosin light chain kinase. Arch Biochem Biophys 2011. [PMID: 21565153 DOI: 10.1016/j.abb.2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The smooth muscle isoform of myosin light chain kinase (MLCK) is a Ca(2+)-calmodulin-activated kinase that is found in many tissues. It is particularly important for regulating smooth muscle contraction by phosphorylation of myosin. This review summarizes selected aspects of recent biochemical work on MLCK that pertains to its function in smooth muscle. In general, the focus of the review is on new findings, unresolved issues, and areas with the potential for high physiological significance that need further study. The review includes a concise summary of the structure, substrates, and enzyme activity, followed by a discussion of the factors that may limit the effective activity of MLCK in the muscle. The interactions of each of the many domains of MLCK with the proteins of the contractile apparatus, and the multi-domain interactions of MLCK that may control its behaviors in the cell are summarized. Finally, new in vitro approaches to studying the mechanism of phosphorylation of myosin are introduced.
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Affiliation(s)
- Feng Hong
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, 89557, USA
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94
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Mouilleron S, Langer CA, Guettler S, McDonald NQ, Treisman R. Structure of a pentavalent G-actin*MRTF-A complex reveals how G-actin controls nucleocytoplasmic shuttling of a transcriptional coactivator. Sci Signal 2011; 4:ra40. [PMID: 21673315 DOI: 10.1126/scisignal.2001750] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Subcellular localization of the actin-binding transcriptional coactivator MRTF-A is controlled by its interaction with monomeric actin (G-actin). Signal-induced decreases in G-actin concentration reduce MRTF-A nuclear export, leading to its nuclear accumulation, whereas artificial increases in G-actin concentration in resting cells block MRTF-A nuclear import, retaining it in the cytoplasm. This regulation is dependent on three actin-binding RPEL motifs in the regulatory domain of MRTF-A. We describe the structures of pentavalent and trivalent G-actin•RPEL domain complexes. In the pentavalent complex, each RPEL motif and the two intervening spacer sequences bound an actin monomer, forming a compact assembly. In contrast, the trivalent complex lacked the C-terminal spacer- and RPEL-actins, both of which bound only weakly in the pentavalent complex. Cytoplasmic localization of MRTF-A in unstimulated fibroblasts also required binding of G-actin to the spacer sequences. The bipartite MRTF-A nuclear localization sequence was buried in the pentameric assembly, explaining how increases in G-actin concentration prevent nuclear import of MRTF-A. Analyses of the pentavalent and trivalent complexes show how actin loads onto the RPEL domain and reveal a molecular mechanism by which actin can control the activity of one of its binding partners.
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Affiliation(s)
- Stéphane Mouilleron
- Structural Biology Group, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
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95
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Characterization of Neurospora crassa α-Actinin. Curr Microbiol 2011; 63:100-5. [DOI: 10.1007/s00284-011-9954-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 05/04/2011] [Indexed: 10/18/2022]
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96
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Biochemistry of smooth muscle myosin light chain kinase. Arch Biochem Biophys 2011; 510:135-46. [PMID: 21565153 DOI: 10.1016/j.abb.2011.04.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 04/22/2011] [Accepted: 04/25/2011] [Indexed: 11/23/2022]
Abstract
The smooth muscle isoform of myosin light chain kinase (MLCK) is a Ca(2+)-calmodulin-activated kinase that is found in many tissues. It is particularly important for regulating smooth muscle contraction by phosphorylation of myosin. This review summarizes selected aspects of recent biochemical work on MLCK that pertains to its function in smooth muscle. In general, the focus of the review is on new findings, unresolved issues, and areas with the potential for high physiological significance that need further study. The review includes a concise summary of the structure, substrates, and enzyme activity, followed by a discussion of the factors that may limit the effective activity of MLCK in the muscle. The interactions of each of the many domains of MLCK with the proteins of the contractile apparatus, and the multi-domain interactions of MLCK that may control its behaviors in the cell are summarized. Finally, new in vitro approaches to studying the mechanism of phosphorylation of myosin are introduced.
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97
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Smock RG, Rivoire O, Russ WP, Swain JF, Leibler S, Ranganathan R, Gierasch LM. An interdomain sector mediating allostery in Hsp70 molecular chaperones. Mol Syst Biol 2011; 6:414. [PMID: 20865007 PMCID: PMC2964120 DOI: 10.1038/msb.2010.65] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 05/20/2010] [Indexed: 11/09/2022] Open
Abstract
Allosteric coupling between protein domains is fundamental to many cellular processes. For example, Hsp70 molecular chaperones use ATP binding by their actin-like N-terminal ATPase domain to control substrate interactions in their C-terminal substrate-binding domain, a reaction that is critical for protein folding in cells. Here, we generalize the statistical coupling analysis to simultaneously evaluate co-evolution between protein residues and functional divergence between sequences in protein sub-families. Applying this method in the Hsp70/110 protein family, we identify a sparse but structurally contiguous group of co-evolving residues called a 'sector', which is an attribute of the allosteric Hsp70 sub-family that links the functional sites of the two domains across a specific interdomain interface. Mutagenesis of Escherichia coli DnaK supports the conclusion that this interdomain sector underlies the allosteric coupling in this protein family. The identification of the Hsp70 sector provides a basis for further experiments to understand the mechanism of allostery and introduces the idea that cooperativity between interacting proteins or protein domains can be mediated by shared sectors.
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Affiliation(s)
- Robert G Smock
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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98
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Chalovich JM, Schroeter MM. Synaptopodin family of natively unfolded, actin binding proteins: physical properties and potential biological functions. Biophys Rev 2010; 2:181-189. [PMID: 28510039 PMCID: PMC5418383 DOI: 10.1007/s12551-010-0040-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 11/01/2010] [Indexed: 12/15/2022] Open
Abstract
The synaptopodin family of proteins consists of at least 3 members: synaptopodin, the synaptopodin 2 proteins, and the synaptopodin 2-like proteins. Each family member has at least 3 isoforms that are produced by alternative splicing. Synaptopodin family members are basic proteins that are rich in proline and have little regular 2° or 3° structure at physiological temperature, pH and ionic strength. Like other natively unfolded proteins, synaptopodin family members have multiple binding partners including actin and other actin-binding proteins. Several members of the synaptopodin family have been shown to stimulate actin polymerization and to bundle actin filaments either on their own or in collaboration with other proteins. Synaptopodin 2 has been shown to accelerate nucleation of actin filament formation and to induce actin bundling. The actin polymerization activity is inhibited by Ca2+-calmodulin. Synaptopodin 2 proteins are localized in Z-bands of striated and heart muscle and dense bodies of smooth muscle cells. Depending on the developmental status and stress, at least one member of the synaptopodin family can occupy nuclei of some cells. Members of the synaptopodin 2 subfamily have been implicated in cancers.
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Affiliation(s)
- Joseph M Chalovich
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, 5E-122 Brody Medical Sciences Building, 600 Moye Blvd, Greenville, NC, 27834, USA.
| | - Mechthild M Schroeter
- Department of Physiology, University of Cologne, Robert-Koch-Str. 39, 50931, Cologne, Germany
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Characterization of engineered actin binding proteins that control filament assembly and structure. PLoS One 2010; 5:e13960. [PMID: 21103060 PMCID: PMC2980482 DOI: 10.1371/journal.pone.0013960] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 10/26/2010] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Eukaryotic cells strictly regulate the structure and assembly of their actin filament networks in response to various stimuli. The actin binding proteins that control filament assembly are therefore attractive targets for those who wish to reorganize actin filaments and reengineer the cytoskeleton. Unfortunately, the naturally occurring actin binding proteins include only a limited set of pointed-end cappers, or proteins that will block polymerization from the slow-growing end of actin filaments. Of the few that are known, most are part of large multimeric complexes that are challenging to manipulate. METHODOLOGY/PRINCIPAL FINDINGS We describe here the use of phage display mutagenesis to generate of a new class of binding protein that can be targeted to the pointed-end of actin. These proteins, called synthetic antigen binders (sABs), are based on an antibody-like scaffold where sequence diversity is introduced into the binding loops using a novel "reduced genetic code" phage display library. We describe effective strategies to select and screen for sABs that ensure the generated sABs bind to the pointed-end surface of actin exclusively. CONCLUSIONS/SIGNIFICANCE From our set of pointed-end binders, we identify three sABs with particularly useful properties to systematically probe actin dynamics: one protein that caps the pointed end, a second that crosslinks actin filaments, and a third that severs actin filaments and promotes disassembly.
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100
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The interaction of capping protein with the barbed end of the actin filament. J Mol Biol 2010; 404:794-802. [PMID: 20969875 DOI: 10.1016/j.jmb.2010.10.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 10/11/2010] [Accepted: 10/12/2010] [Indexed: 11/21/2022]
Abstract
The interaction of capping protein (CP) with actin filaments is an essential element of actin assembly and actin-based motility in nearly all eukaryotes. The dendritic nucleation model for Arp2/3-based lamellipodial assembly features capping of barbed ends by CP, and the formation of filopodia is proposed to involve inhibition of capping by formins and other proteins. To understand the molecular basis for how CP binds the barbed end of the actin filament, we have used a combination of computational and experimental approaches, primarily involving molecular docking and site-directed mutagenesis. We arrive at a model that supports all of our biochemical data and agrees very well with a cryo-electron microscopy structure of the capped filament. CP interacts with both actin protomers at the barbed end of the filament, and the amphipathic helix at the C-terminus of the β-subunit binds to the hydrophobic cleft on actin, in a manner similar to that of WH2 domains. These studies provide us with new molecular insight into how CP binds to the actin filament.
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