Plectin: A Cytolinker by Design

1999 ◽  
Vol 380 (2) ◽  
pp. 151-158 ◽  
Author(s):  
F.A. Steinböck ◽  
G. Wiche
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Transmembrane Protein ◽  
Coiled Coil ◽  
Cytoskeletal Protein ◽  
Terminal Domain ◽  
Junctional Proteins ◽  
Molecular Backbone ◽  
Cytoskeletal Elements

Abstract Plectin is a cytoskeletal protein of > 500 kDa that forms dumbbell-shaped homodimers comprising a central parallel α-helical coiled coil rod domain flanked by globular domains, thus providing a molecular backbone ideally suited to mediate the protein's interactions with an array of other cytoskeletal elements. Plectin self-associates and interacts with actin and intermediate filament cytoskeleton networks at opposite ends, and it binds at both ends to the hemidesmosomal transmembrane protein integrin beta-4, and likely to other junctional proteins. The central coiled coil rod domain can form bridges over long stretches and serves as a flexible linker between the structurally diverse N-terminal domain and the highly conserved C-terminal domain. Plectin is also a target of p34cdc2 kinase that regulates its dissociation from intermediate filaments during mitosis.

scholarly journals Expression of plectin mutant cDNA in cultured cells indicates a role of COOH-terminal domain in intermediate filament association.

1993 ◽  
Vol 121 (3) ◽  
pp. 607-619 ◽  
Author(s):  
G Wiche ◽  
D Gromov ◽  
A Donovan ◽  
M J Castañón ◽  
E Fuchs
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Cultured Cells ◽  
Globular Domain ◽  
Mutant Proteins ◽  
Terminal Domain ◽  
Confocal Immunofluorescence Microscopy ◽  
Terminal Repeats ◽  
Carboxy Terminal

Plectin is an intermediate filament (IF) binding protein of exceptionally large size. Its molecular structure, revealed by EM and predicted by its sequence, indicates an NH2-terminal globular domain, a long rodlike central domain, and a globular COOH-terminal domain containing six highly homologous repeat regions. To examine the role of the various domains in mediating plectin's interaction with IFs, we have constructed rat cDNAs encoding truncated plectin mutants under the control of the SV-40 promoter. Mutant proteins expressed in mammalian COS and PtK2 cells could be distinguished from endogenous wild type plectin by virtue of a short carboxy-terminal antigenic peptide (P tag). As shown by conventional and confocal immunofluorescence microscopy, the transient expression of plectin mutants containing all six or the last four of the repeat regions of the COOH-terminus, or the COOH-terminus and the rod, associated with IF networks of both the vimentin and the cytokeratin type and eventually caused their collapse into perinuclear aggregates. Similar effects were observed upon expression of a protein encoded by a full length cDNA construct. Microtubules and microfilaments were unaffected. Unexpectedly, mutants containing the rod without any of the COOH-terminal repeats, accumulated almost exclusively within the nuclei of cells. When the rod was extended by the first one and a half of the COOH-terminal repeats, mutant proteins showed a partial cytoplasmic distribution, although association with intermediate filaments was not observed. Nuclear and diffuse cytoplasmic distribution was also observed upon expression of the NH2-terminal domain without rod. These results indicate that sequences located roughly within the last two thirds of the globular COOH-terminus are indispensable for association of plectin with intermediate filaments in living cells.

scholarly journals Keratins and plakin family cytolinker proteins control the length of epithelial microridge protrusions

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Yasuko Inaba ◽  
Vasudha Chauhan ◽  
Aaron Paul van Loon ◽  
Lamia Saiyara Choudhury ◽  
Alvaro Sagasti
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Actin Filaments ◽  
Actin Binding ◽  
Protein Levels ◽  
Skin Cells ◽  
Keratin Filaments ◽  
Actin Binding Domain ◽  
Cytoskeletal Elements ◽  
Keratin Intermediate Filaments

Actin filaments and microtubules create diverse cellular protrusions, but intermediate filaments, the strongest and most stable cytoskeletal elements, are not known to directly participate in the formation of protrusions. Here we show that keratin intermediate filaments directly regulate the morphogenesis of microridges, elongated protrusions arranged in elaborate maze-like patterns on the surface of mucosal epithelial cells. We found that microridges on zebrafish skin cells contained both actin and keratin filaments. Keratin filaments stabilized microridges, and overexpressing keratins lengthened them. Envoplakin and periplakin, plakin family cytolinkers that bind F-actin and keratins, localized to microridges, and were required for their morphogenesis. Strikingly, plakin protein levels directly dictate microridge length. An actin-binding domain of periplakin was required to initiate microridge morphogenesis, whereas periplakin-keratin binding was required to elongate microridges. These findings separate microridge morphogenesis into distinct steps, expand our understanding of intermediate filament functions, and identify microridges as protrusions that integrate actin and intermediate filaments.

Intermediate filaments: molecular architecture, assembly, dynamics and polymorphism

1999 ◽  
Vol 32 (2) ◽  
pp. 99-187 ◽  
Author(s):  
David A. D. Parry ◽  
Peter M. Steinert
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Tertiary Structure ◽  
Quaternary Structure ◽  
Lattice Structure ◽  
Coiled Coil ◽  
Salt Bridges ◽  
Molecular Architecture

1. Introduction 1002. Molecular architecture 1072.1 Primary structure 1082.1.1 Homologous regions 1092.1.2 Chain typing 1152.1.3 Post-translational modifications 1172.2 Secondary structure 1182.2.1 Central rod domain 1182.2.2 Head and tail domains 1192.3 Tertiary structure 1232.3.1 Coiled-coil rod domain 1232.3.1.1 Specificity through salt bridges 1242.3.1.2 Specificity through apolar interactions 1272.3.1.3 A consensus trigger sequence for two-stranded coiled-coils 1282.3.2 Discontinuities in the rod domain 1282.3.2.1 Links 1292.3.2.2 Stutter 1312.3.3 Head and tail domains 1312.4 Electron microscope observations 1333. Assembly 1363.1 Role of the coiled-coil rod domain 1373.2 Role of end domains 1413.3 Experimentally induced crosslinks and modes of assembly 1453.4 Naturally occurring crosslinks for tissue coordination 1543.5 STEM data 1544. Quaternary structure 1604.1 Protofilaments and protofibrils 1604.2 Head and tail domains 1634.3 Surface lattice structure 1644.4 Crystal studies on intermediate filament fragments 1685. Polymorphism 1695.1 Variations on a theme 1705.1.1 Axial structure 1705.1.2 Lateral structure 1716. Keratin intermediate filament chains in diseases 1727. Concluding remarks 1758. Acknowledgments 1769. References 176Three types of intracellular filament have been identified in eukaryotic cells, and together they constitute the key elements of the cytoskeleton. They are the microtubules, the actin-containing microfilaments and the intermediate filaments. The uniqueness of the former two types of filament in cells has been well known for a long time but, in contrast, the intermediate filaments have been a relative new-comer to the scene. The microtubules and the microfilaments have always been easy to distinguish from one another on the grounds of their respective sizes (microtubules are about 25 nm in diameter and microfilaments are about 7–10 nm in diameter). Additionally, microtubules were capable of being disaggregated by the action of colchicine, and microfilaments could be disassembled by other drugs or be decorated with heavy meromyosin to generate arrowhead-like structures. Importantly, in both microtubules and microfilaments the constituent protein subunits were arranged to give the filaments a directionality, and the ability of these filaments to function in vivo depended crucially on this feature of their structure. Microtubules, for example, are involved in mitosis, motility and transport within the cell: each of these functions is clearly a ‘directional’ one. With this background the discovery and characterization of the intermediate filaments can begin.

Intermediate filament formation after transfection with modified hamster vimentin and desmin genes

1987 ◽  
Vol 88 (4) ◽  
pp. 475-482
Author(s):  
R.M. van den Heuvel ◽  
G.J. van Eys ◽  
F.C. Ramaekers ◽  
W.J. Quax ◽  
W.T. Vree Egberts ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Filament Formation ◽  
Molecular Weights ◽  
Terminal Domain ◽  
Bona Fide ◽  
Terminal Amino

Previously we cloned and characterized the hamster intermediate filament genes coding for vimentin and desmin. It was demonstrated that the cloned desmin gene was expressed after gene transfer and that the newly synthesized protein assembles into intermediate filaments. Here we present data on the transfection of modified vimentin and desmin genes onto simian virus 40-transformed hamster lens cells and HeLa cells. Modifications included: (1) removal of exons encoding the desmin COOH-terminal domain; (2) exchange of exons encoding the COOH-terminal domain of vimentin and desmin; and (3) deletion of part of exon I of desmin, coding for the NH2-terminal amino acids 4–148. In transient transfection assays it was shown that the modifications in the COOH region had no detectable effects on the filament forming potential of the encoded proteins as demonstrated with desmin antibodies in the indirect immunofluorescence test. On the other hand, deletion of a considerable part of the first exon of the desmin gene results in a lack of bona fide intermediate filament formation. Immunoblotting with desmin antibodies of cell populations enriched for the transfected modified genes showed that the presence of the modified genes results in the synthesis of the corresponding proteins with the expected molecular weights. From our results we conclude that in vivo: (1) the presence of the COOH terminus is not essential for filament formation; (2) that an exchange of COOH-terminal parts of vimentin and desmin does not prevent assembly into intermediate filaments; and (3) that removal of the NH2 terminus of desmin affects intermediate filament formation.

scholarly journals Assembly mechanisms of the bacterial cytoskeletal protein FilP

2019 ◽  
Vol 2 (3) ◽  
pp. e201800290 ◽  
Author(s):  
Ala Javadi ◽  
Niklas Söderholm ◽  
Annelie Olofsson ◽  
Klas Flärdh ◽  
Linda Sandblad
Keyword(s):  
Intermediate Filament ◽  
Sequence Homology ◽  
Building Block ◽  
Streptomyces Coelicolor ◽  
Coiled Coil ◽  
Cytoskeletal Protein ◽  
Basic Building Block ◽  
Assembly Model ◽  
Filament Bundles ◽  
Bundle Structure

Despite low-sequence homology, the intermediate filament (IF)–like protein FilP from Streptomyces coelicolor displays structural and biochemical similarities to the metazoan nuclear IF lamin. FilP, like IF proteins, is composed of central coiled-coil domains interrupted by short linkers and flanked by head and tail domains. FilP polymerizes into repetitive filament bundles with paracrystalline properties. However, the cations Na+ and K+ are found to induce the formation of a FilP hexagonal meshwork with the same 60-nm repetitive unit as the filaments. Studies of polymerization kinetics, in combination with EM techniques, enabled visualization of the basic building block—a transiently soluble rod-shaped FilP molecule—and its assembly into protofilaments and filament bundles. Cryoelectron tomography provided a 3D view of the FilP bundle structure and an original assembly model of an IF-like protein of prokaryotic origin, thereby enabling a comparison with the assembly of metazoan IF.

scholarly journals Dynamic structural order of a low complexity domain facilitates assembly of intermediate filaments

2020 ◽  
Author(s):  
Vasily O. Sysoev ◽  
Masato Kato ◽  
Lillian Sutherland ◽  
Rong Hu ◽  
Steven L. McKnight ◽  
...  
Keyword(s):  
Protein Folding ◽  
Intermediate Filaments ◽  
Cell Morphology ◽  
Intermediate Filament ◽  
Coiled Coil ◽  
Low Complexity ◽  
Tail Domain ◽  
Sequence Complexity ◽  
New Form

AbstractThe coiled-coil domains of intermediate filament (IF) proteins are flanked by regions of low sequence complexity. Whereas IF coiled-coil domains assume dimeric and tetrameric conformations on their own, maturation of eight tetramers into cylindrical IFs is dependent upon either “head” or “tail” domains of low sequence complexity. Here we confirm that the tail domain required for assembly of Drosophila Tm1 IFs functions by forming labile cross-β interactions. These interactions are seen in polymers made from the tail domain alone as well as assembled IFs formed by the intact Tm1 protein. The ability to visualize such interactions in situ within the context of a discrete cellular assembly lends support to the concept that equivalent interactions may be used in organizing other dynamic aspects of cell morphology.One Sentence SummaryA new form of protein folding that interconverts between the structured and unstructured states controls assembly of intermediate filaments.

scholarly journals Dynamic structural order of a low-complexity domain facilitates assembly of intermediate filaments

2020 ◽  
Vol 117 (38) ◽  
pp. 23510-23518
Author(s):  
Vasiliy O. Sysoev ◽  
Masato Kato ◽  
Lillian Sutherland ◽  
Rong Hu ◽  
Steven L. McKnight ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Cell Morphology ◽  
Intermediate Filament ◽  
Coiled Coil ◽  
Low Complexity ◽  
Tail Domain ◽  
C Protein ◽  
Sequence Complexity ◽  
Structural Order

The coiled-coil domains of intermediate filament (IF) proteins are flanked by regions of low sequence complexity. Whereas IF coiled-coil domains assume dimeric and tetrameric conformations on their own, maturation of eight tetramers into cylindrical IFs is dependent on either “head” or “tail” domains of low sequence complexity. Here we confirm that the tail domain required for assembly ofDrosophilaTm1-I/C IFs functions by forming labile cross-β interactions. These interactions are seen in polymers made from the tail domain alone, as well as in assembled IFs formed by the intact Tm1-I/C protein. The ability to visualize such interactions in situ within the context of a discrete cellular assembly lends support to the concept that equivalent interactions may be used in organizing other dynamic aspects of cell morphology.

scholarly journals Effects of mechanical tension on protrusive activity and microfilament and intermediate filament organization in an epidermal epithelium moving in culture.

1986 ◽  
Vol 102 (4) ◽  
pp. 1400-1411 ◽  
Author(s):  
J Kolega
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Mechanical Tension ◽  
Cytoskeletal Organization ◽  
Structural Support ◽  
Transmission Electron ◽  
Locomotive Activity ◽  
Filament Surface

Mechanical tension influences tissue morphogenesis and the synthetic, mitotic, and motile behavior of cells. To determine the effects of tension on epithelial motility and cytoskeletal organization, small, motile clusters of epidermal cells were artificially extended with a micromanipulated needle. Protrusive activity perpendicular to the axis of tension was dramatically suppressed. To determine the ultrastructural basis for this phenomenon, cells whose exact locomotive behavior was recorded cinemicrographically were examined by transmission electron microscopy. In untensed, forward-moving lamellar protrusions, microfilaments appear disorganized and anisotropically oriented. But in cytoplasm held under tension by micromanipulation or by the locomotive activity of other cells within the epithelium, microfilaments are aligned parallel to the tension. In non-spreading regions of the epithelial margin, microfilaments lie in tight bundles parallel to apparent lines of tension. Thus, it appears that tension causes alignment of microfilaments. In contrast, intermediate filaments are excluded from motile protrusions, being confined to the thicker, more central part of the cell. They roughly follow the contours of the cell, but are not aligned relative to tension even when microfilaments in the same cell are. This suggests that the organization of intermediate filaments is relatively resistant to physical distortion and the intermediate filaments may act as passive structural support within the cell. The alignment of microfilaments under tension suggests a mechanism by which tension suppresses protrusive activity: microfilaments aligned by forces exerted through filament-surface or filament-filament interconnections cannot reorient against such force and so cannot easily extend protrusions in directions not parallel to tension.

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