1351
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1352
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1353
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Houmeida A, Hanin V, Feinberg J, Benyamin Y, Roustan C. Definition of a Ca2(+)-sensitive interface in the plasma gelsolin-actin complex. Biochem J 1991; 274 ( Pt 3):753-7. [PMID: 1849405 PMCID: PMC1149975 DOI: 10.1042/bj2740753] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gelsolin is a Ca2(+)-dependent protein which severs actin filaments, caps their fast-growing ends and promotes nucleation. We report here results that delimit one of the interfaces between serum gelsolin and actin monomer. An actin-derived synthetic peptide (amino acids 305-326 of actin) coupled to a hydrophilic resin was tested for its possible interaction with gelsolin. We selected this sequence because it corresponds to a region implicated in the gelsolin-actin complex in a previous work [Boyer, Feinberg, Hue, Capony, Benyamin & Roustan (1987) Biochem. J. 248, 359-364]. We showed that this actin sequence is located at the surface of the actin molecule and observed a Ca2(+)-sensitive binding of gelsolin to this actin-derived peptide. In addition, by using a chymotryptic digest of gelsolin, we reported that only the C-terminal half of gelsolin interacts with the actin-(305-326)-peptide. These results that the Ca2(+)-sensitive interface includes both amino acids 305-326 of actin and probably amino acids 660-738 of gelsolin.
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Affiliation(s)
- A Houmeida
- UPR 8402 Centre de Recherches de Biochimie Macromoléculaire CNRS, U249 INSERM, Université de Montpellier, France
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1354
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Pope B, Way M, Weeds AG. Two of the three actin-binding domains of gelsolin bind to the same subdomain of actin. Implications of capping and severing mechanisms. FEBS Lett 1991; 280:70-4. [PMID: 1849098 DOI: 10.1016/0014-5793(91)80206-i] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gelsolin binds two monomers in the nucleating complex with G-actin in calcium and caps actin filaments. However, 3 actin-binding domains have been identified within its 6 repeating sequence segments corresponding to S1 S2-3 and S4-6. S1 and S4-6 bind only G-actin whereas S2-3 binds specifically to F-actin. Two of the three domains (S2-3 and S4-6) are required for nucleation and a different pair (S1 and S2-3) for severing. Here we show for the first time that the domains unique to nucleation (S4-6) or severing (S1) compete for the same region on subdomain 1 of G-actin. We further show that S2-3 binds actin monomers weakly in G-buffer conditions and that this interaction persists when S1 or S4-6 are also bound. Thus gelsolin associates with two distinct regions on actin. Since S2-3 does not bind monomeric actin in F-buffer, we suggest that its high affinity 1:1 stoichiometry for filament subunits reflects interaction with two adjacent subunits.
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Affiliation(s)
- B Pope
- MRC Laboratory of Molecular Biology, Cambridge, UK
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1355
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Holm L, Sander C. Database algorithm for generating protein backbone and side-chain co-ordinates from a C alpha trace application to model building and detection of co-ordinate errors. J Mol Biol 1991; 218:183-94. [PMID: 2002501 DOI: 10.1016/0022-2836(91)90883-8] [Citation(s) in RCA: 243] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The problem of constructing all-atom model co-ordinates of a protein from an outline of the polypeptide chain is encountered in protein structure determination by crystallography or nuclear magnetic resonance spectroscopy, in model building by homology and in protein design. Here, we present an automatic procedure for generating full protein co-ordinates (backbone and, optionally, side-chains) given the C alpha trace and amino acid sequence. To construct backbones, a protein structure database is first scanned for fragments that locally fit the chain trace according to distance criteria. A best path algorithm then sifts through these segments and selects an optimal path with minimal mismatch at fragment joints. In blind tests, using fully known protein structures, backbones (C alpha, C, N, O) can be reconstructed with a reliability of 0.4 to 0.6 A root-mean-square position deviation and not more than 0 to 5% peptide flips. This accuracy is sufficient to identify possible errors in protein co-ordinate sets. To construct full co-ordinates, side-chains are added from a library of frequently occurring rotamers using a simple and fast Monte Carlo procedure with simulated annealing. In tests on X-ray structures determined at better than 2.5 A resolution, the positions of side-chain atoms in the protein core (less than 20% relative accessibility) have an accuracy of 1.6 A (r.m.s. deviation) and 70% of chi 1 angles are within 30 degrees of the X-ray structure. The computer program MaxSprout is available on request.
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1356
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Abstract
The challenge presented by myofibril assembly in striated muscle is to understand the molecular mechanisms by which its protein components are arranged at each level of organization. Recent advances in the genetics and cell biology of muscle development have shown that in vivo assembly of the myofilaments requires a complex array of structural and associated proteins and that organization of whole sarcomeres occurs initially at the cell membrane. These studies have been complemented by in vitro analyses of the renaturation, polymerization, and three-dimensional structure of the purified proteins.
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Affiliation(s)
- H F Epstein
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030
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1357
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A reversible conformational transition in muscle actin is caused by nucleotide exchange and uncovers cysteine in position 10. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67623-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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1358
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McKay DB. Structure of the 70-kilodalton heat-shock-related proteins. SPRINGER SEMINARS IN IMMUNOPATHOLOGY 1991; 13:1-9. [PMID: 1776119 DOI: 10.1007/bf01225274] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- D B McKay
- Beckman Laboratories for Structural Biology, Department of Cell Biology, Stanford University School of Medicine, CA 94305-5400
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1359
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Abstract
Mutants of the Drosophila Act88F actin gene were transcribed and translated in vitro and their relative stabilities were examined using urea gradient gel electrophoresis. Most of the mutant actins (E334K, E364K, G366D, G368E and R372H) were as stable as the wild-type. V339I had a slight decrease in stability, and E316K was the least stable. The causes of the differences are discussed and contrasted with the behaviour of the mutants in vivo, where E316K has normal stability and V339I is the least stable.
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1360
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Geeves MA. The dynamics of actin and myosin association and the crossbridge model of muscle contraction. Biochem J 1991; 274 ( Pt 1):1-14. [PMID: 1825780 PMCID: PMC1150189 DOI: 10.1042/bj2740001] [Citation(s) in RCA: 163] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M A Geeves
- Department of Biochemistry, School of Medical Sciences, University of Bristol, U.K
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1361
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Strambini GB, Lehrer SS. Tryptophan phosphorescence of G-actin and F-actin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 195:645-51. [PMID: 1999187 DOI: 10.1111/j.1432-1033.1991.tb15749.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The tryptophan phosphorescence spectrum, intensity and decay kinetics of G-actin and F-actin were measured over a temperature range of 140-293 K. The fine structure in the phosphorescence spectra at low temperature, with O,O vibrational bands centered at 405 nm and 415.5 nm for both species, reveals a marked heterogeneity of the chromophore environment. The thermal quenching profile distinguishes these sites in terms of their flexibility, and shows that probably only one of the four tryptophan residues is still phosphorescent at ambient temperature due to its location in a relatively rigid buried core. Although some differences are demonstrated between G-actin and F-actin at low temperature, the identity of the triplet lifetime at ambient temperature strongly supports the notion that the conformation of the macromolecule is largely unaffected by polymerization. Preliminary phosphorescence anisotropy measurements demonstrate both the occurrence of singlet-singlet energy transfer among tryptophan residues and a strong immobilization of actin in the polymerized state.
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1362
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1363
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Pollard TD, Goldman RD. Editorial overview. Curr Opin Cell Biol 1991. [DOI: 10.1016/0955-0674(91)90158-u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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1364
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Abstract
Two major polymers of the cytoskeleton, actin filaments and microtubules, are assembled with expenditure of energy: the ATP/GTP tightly bound to actin/tubulin is irreversibly hydrolyzed to ADP/GTP during the assembly process, and liberation of Pi in the medium occurs subsequent to the incorporation of subunits in the polymer. Pi release acts as a switch, causing the destabilization of protein-protein interactions in the polymer, therefore regulating the dynamics of these fibres. An understanding of this regulation in vivo requires that progress be made in four areas: the chemistry of the NTPase reaction; the structure of the intermediates in nucleotide hydrolysis and the nature of the conformational switch; the regulation of parameters involved in dynamic instability of microtubules; and the possible involvement of nucleotide hydrolysis in the macroscopic organization of these polymers in highly concentrated solutions, compared with the simple case of a equilibrium polymers. Progress made along these lines will define trends for future investigation.
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Affiliation(s)
- M F Carlier
- Laboratoire d'Enzymologie, CNRS, Gif-sur-Yvette, France
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1365
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1366
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McPhalen CA, Strynadka NC, James MN. Calcium-binding sites in proteins: a structural perspective. ADVANCES IN PROTEIN CHEMISTRY 1991; 42:77-144. [PMID: 1793008 DOI: 10.1016/s0065-3233(08)60535-5] [Citation(s) in RCA: 183] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- C A McPhalen
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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1367
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1368
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Burns RG. Alpha-, beta-, and gamma-tubulins: sequence comparisons and structural constraints. CELL MOTILITY AND THE CYTOSKELETON 1991; 20:181-9. [PMID: 1773446 DOI: 10.1002/cm.970200302] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Comparison of congruent to 160 alpha-, beta-, and gamma-tubulins, and excluding the highly divergent C-terminal peptide, indicates that the three subclasses have similar tertiary structures. Conserved sequences within or between the subclasses have been identified, together with the locations of known epitopes, chemical modifications, and mutations. Evidence is also reviewed concerning the identity of the GTP-binding sites, about which residues are exposed in the assembled microtubule and at subunit:subunit interfaces. These characteristics constrain the possible tertiary structure of the tubulin subunit.
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Affiliation(s)
- R G Burns
- Biophysics Section, Blackett Laboratory, Imperial College of Science, Technology and Medicine, London, United Kingdom
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1369
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1370
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Considine RV, Simpson LL. Cellular and molecular actions of binary toxins possessing ADP-ribosyltransferase activity. Toxicon 1991; 29:913-36. [PMID: 1949064 DOI: 10.1016/0041-0101(91)90076-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Clostridial organisms produce a number of binary toxins. Thus far, three complete toxins (botulinum, perfringens and spiroforme) and one incomplete toxin (difficile) have been identified. In the case of complete toxins, there is a heavy chain component (Mr approximately 100,000) that binds to target cells and helps create a docking site for the light chain component (Mr approximately 50,000). The latter is an enzyme that possesses mono(ADP-ribosyl)transferase activity. The toxins appear to proceed through a three step sequence to exert their effects, including a binding step, an internalization step and an intracellular poisoning step. The substrate for the toxins is G-actin. By virtue of ADP-ribosylating monomeric actin, the toxins prevent polymerization as well as promoting depolymerization. The most characteristic cellular effect of the toxins is alteration of the cytoskeleton, which leads directly to changes in cellular morphology and indirectly to changes in cell function (e.g. release of chemical mediators). Binary toxins capable of modifying actin are likely to be useful tools in the study of cell biology.
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Affiliation(s)
- R V Considine
- Department of Physiology, Jefferson Medical College, Philadelphia, PA
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1371
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Polzar B, Mannherz HG. Nucleotide sequence of a full length cDNA clone encoding the deoxyribonuclease I from the rat parotid gland. Nucleic Acids Res 1990; 18:7151. [PMID: 2263485 PMCID: PMC332797 DOI: 10.1093/nar/18.23.7151] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- B Polzar
- Institut für Anatomie und Zellbiologie, der Universität Marburg, Germany
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1372
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Lebart MC, Méjean C, Boyer M, Roustan C, Benyamin Y. Localization of a new alpha-actinin binding site in the COOH-terminal part of actin sequence. Biochem Biophys Res Commun 1990; 173:120-6. [PMID: 2124107 DOI: 10.1016/s0006-291x(05)81030-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The interaction of filamentous actin with alpha-actinin, an actin cross-linking protein, is well established. On the other hand, monomeric actin-alpha-actinin interaction has been a subject of controversy. In this report, we have characterized the interaction of monomeric actin, coated on plastic plates under conditions of non-polymerization, with alpha-actinin in presence of magnesium. Using specific polyclonal anti-actin antibodies, with the whole molecule or purified peptides, we have localized two sites of interaction on action molecule: one near Thr-103 and a new one in the twenty last amino acids.
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Affiliation(s)
- M C Lebart
- Centre de Recherches de Biochimie Macromoléculaire (CNRS), U. 249 (INSERM), Université de Montpellier I, France
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1373
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Drummond DR, Peckham M, Sparrow JC, White DC. Alteration in crossbridge kinetics caused by mutations in actin. Nature 1990; 348:440-2. [PMID: 2123302 DOI: 10.1038/348440a0] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The generation of force during muscle contraction results from the interaction of myosin and actin. The kinetics of this force generation vary between different muscle types and within the same muscle type in different species. Most attention has focused on the role of myosin isoforms in determining these differences. The role of actin isoforms has received little attention, largely because of the lack of a suitable cell type in which the myosin isoform remains constant yet the actin isoforms vary. An alternative approach would be to examine the effect of actin mutations, however, most of these cause such gross disruption of muscle structure that mechanical measurements are impossible. We have now identified two actin mutations which, despite involving conserved amino acids, can assemble into virtually normal myofibrils. These amino-acid changes in actin significantly affect the kinetics of force generation by muscle fibres. One of the mutations is not in the putative myosin-binding site, demonstrating the importance of long-range effects of amino acids on actin function.
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1374
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Milligan RA, Whittaker M, Safer D. Molecular structure of F-actin and location of surface binding sites. Nature 1990; 348:217-21. [PMID: 2234090 DOI: 10.1038/348217a0] [Citation(s) in RCA: 314] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Comparisons of three-dimensional maps of vertebrate muscle thin filaments obtained by cryo-electron microscopy and image analysis, reveal the molecular structure of F-actin, the location of the C terminus of the monomer and the positions of the binding sites of tropomyosin, the myosin head and the N-terminal portion of the myosin A1 light chain on the filament. These data provide strong constraints for evaluating models built from the atomic structure of the monomer and the subsequent identification of molecular contacts.
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Affiliation(s)
- R A Milligan
- Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037
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1375
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Abstract
The F-actin filament has been constructed from the atomic structure of the actin monomer to fit the observed X-ray fibre diagram from oriented gels of F-actin. A unique orientation of the monomer with respect to the actin helix has been found. The main interactions are along the two-start helix with a contribution from a loop extending across the filament axis provided by the molecule in the adjacent strand. There are also contacts along the left-handed genetic helix.
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Affiliation(s)
- K C Holmes
- Max-Planck-Institut für Medizinische Forschung, Abteilung Biophysik, Heidelberg, FRG
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