1: Exp Cell Res. 2007 Jun 10;313(10):2204-16. Epub 2007 Apr 12.


Towards a molecular description of intermediate filament structure and assembly.

Parry DA, Strelkov SV, Burkhard P, Aebi U, Herrmann H.

Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.

Intermediate filaments (IFs) represent one of the prominent cytoskeletal elements of metazoan cells. Their constituent proteins are coded by a multigene family, whose members are expressed in complex patterns that are controlled by developmental programs of differentiation. Hence, IF proteins found in epidermis differ significantly from those in muscle or neuronal tissues. Due to their fibrous nature, which stems from a fairly conserved central alpha-helical coiled-coil rod domain, IF proteins have long resisted crystallization and thus determination of their atomic structure. Since they represent the primary structural elements that determine the shape of the nucleus and the cell more generally, a major challenge is to arrive at a more rational understanding of how their nanomechanical properties effect the stability and plasticity of cells and tissues. Here, we review recent structural results of the coiled-coil dimer, assembly intermediates and growing filaments that have been obtained by a hybrid methods approach involving a rigorous combination of X-ray crystallography, small angle X-ray scattering, cryo-electron tomography, computational analysis and molecular modeling.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 17521629 [PubMed - indexed for MEDLINE]

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2: Adv Protein Chem. 2005;70:113-42.


Microdissection of the sequence and structure of intermediate filament chains.

Parry DA.

Institute of Fundamental Sciences, Massey University, Palmerston North 5301, New Zealand.

A large number of intermediate filament (IF) chains have now been sequenced. From these data, it has been possible to deduce the main elements of the secondary structure, especially those lying within the central rod domain of the molecule. These conclusions, allied to results obtained from crosslinking studies, have shown that at least four unique but related structures are adopted by the class of structures known generically as intermediate filaments: (1) epidermal and reduced trichocyte keratin; (2) oxidized trichocyte keratin; (3) desmin, vimentin, neurofilaments, and related Type III and IV proteins; and (4) lamin molecules. It would be expected that local differences in sequences of the proteins in these four groups would occur, and that this would ultimately relate to assembly. Site-directed mutagenesis and theoretical methods have now made it possible to investigate these ideas further. In particular, new data have been obtained that allow the role played by some individual amino acids or a short stretch of sequence to be determined. Among the observations catalogued here are the key residues involved in intra- and interchain ionic interactions, as well as those involved in stabilizing some modes of molecular aggregation; the structure and role of subdomains in the head and tail domains; the repeat sequences occurring along the length of the chain and their structural significance; trigger motifs in coiled-coil segments; and helix initiation and termination motifs that terminate the rod domain. Much more remains to be done, not least of which is gaining an increased understanding of the many subtle differences that exist between different IF chains at the sequence level.

Publication Types:
Review

PMID: 15837515 [PubMed - indexed for MEDLINE]

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3: Int Rev Cytol. 2003;223:83-175.


Functional complexity of intermediate filament cytoskeletons: from structure to assembly to gene ablation.

Herrmann H, Hesse M, Reichenzeller M, Aebi U, Magin TM.

Division of Cell Biology, German Cancer Research Center, D-69120 Heidelberg, Germany.

The cell biology of intermediate filament (IF) proteins and their filaments is complicated by the fact that the members of the gene family, which in humans amount to at least 65, are differentially expressed in very complex patterns during embryonic development. Thus, different tissues and cells express entirely different sets and amounts of IF proteins, the only exception being the nuclear B-type lamins, which are found in every cell. Moreover, in the course of evolution the individual members of this family have, within one species, diverged so much from each other with regard to sequence and thus molecular properties that it is hard to envision a unifying kind of function for them. The known epidermolytic diseases, caused by single point mutations in keratins, have been used as an argument for a role of IFs in mechanical "stress resistance," something one would not have easily ascribed to the beaded chain filaments, a special type of IF in the eye lens, or to nuclear lamins. Therefore, the power of plastic dish cell biology may be limited in revealing functional clues for these structural elements, and it may therefore be of interest to go to the extreme ends of the life sciences, i.e., from the molecular properties of individual molecules including their structure at the atomic level to targeted inactivation of their genes in living animals, mouse, and worm to define their role more precisely in metazoan cell physiology.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 12641211 [PubMed - indexed for MEDLINE]

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4: Subcell Biochem. 1998;31:1-33.


Fish intermediate filament proteins in structure, evolution, and function.

Markl J, Schechter N.

Institute of Zoology, Johannes Gutenberg University of Mainz, Germany.

Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 9932488 [PubMed - indexed for MEDLINE]

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5: J Struct Biol. 1998;122(1-2):67-75.


Hard alpha-keratin intermediate filament chains: substructure of the N- and C-terminal domains and the predicted structure and function of the C-terminal domains of type I and type II chains.

Parry DA, North AC.

Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.

The quantity of sequence data now available for both Type I and Type II hard alpha-keratin IF proteins makes it possible to analyze their N- and C-terminal domains and ascertain features of likely structural and/or functional importance. The N-terminal domains of both chain types can be divided into acidic (NA) and basic (NB) subdomains, where NA is 29 and 34 residues long, respectively, for Type I and II chains and is located immediately adjacent to the end of the rod domain. NB constitutes the remainder of the N-terminal domain and is about 27 and 70 residues long for the two chain types, respectively. The glycine residue contents, however, are high in NA(I) and NB(II), but low in NA(II) and NB(I). Subdomain NB(II) contains four consecutive nonapeptide quasirepeats of the form GGGFGYRSX. The C-terminal domain of Type I chains, termed C(I), is characterized by a PCX motif repeated 10 times, 7 of them contiguously. From an analysis of the conformation of like peptides from crystal structures it has been shown that this region will probably adopt a polyproline II left-handed helical structure with three residues per turn. In contrast, the C-terminal domain of Type II hard alpha-keratin chains (known as C(II)) contains a periodic distribution of hydrophobicities that, together with other predictive techniques, allow its conformation (a twisted four-stranded antiparallel beta-sheet) to be predicted with some degree of confidence. In addition, it is possible to suggest two partners with which this domain will interact. The first is with segment L12 in the rod domain and the second is with another C(II) domain in an antiparallel neighboring molecule. The latter possibility appears most likely. In either case the aggregation would likely serve to stabilize the molecular assembly through the interaction of two beta-sheets via their apolar faces and, in so doing, would position a number of cysteine residues in external positions that would allow them to form a number of covalent disulfide bonds with other molecules. Copyright 1998 Academic Press.

Publication Types:
Review

PMID: 9724606 [PubMed - indexed for MEDLINE]

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6: Curr Opin Cell Biol. 1993 Feb;5(1):3-11.


Intermediate filament structure and assembly.

Stewart M.

MRC Laboratory of Molecular Biology, Cambridge, UK.

Intermediate filaments are constructed from two-chain alpha-helical coiled-coil molecules arranged on an imperfect helical lattice. Filament structure and assembly can be influenced at several different structural levels, including molecular structure, oligomer formation and filament nucleation and elongation. Consequently, it can sometimes be difficult to interpret mutagenesis data unequivocally, although regions near the amino and carboxyl termini of the rod domain of the molecule are known to be important for the production of native filaments. Imperfections in molecular packing may be important in filament assembly and dynamics.

Publication Types:
Review

PMID: 8448027 [PubMed - indexed for MEDLINE]

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7: Curr Opin Cell Biol. 1992 Feb;4(1):94-8.


Intermediate filament structure.

Parry DA, Steinert PM.

Department of Physics and Biophysics, Massey University, Palmerston North, New Zealand.

In the past year, several new developments concerning the structure of intermediate filament proteins and their assembly into intact intermediate filaments have been made: the coiled-coil structure of a rod domain has been elucidated; the basis of the chain interaction and its role in intermediate filament assembly has been specified; the organization of nearest-neighbour molecules in keratin intermediate filaments has been determined; and the glycine loop structures of the terminal domains of epidermal keratin chains have been defined. In addition, mutations in intermediate filament chains that promote pathology have been reported for the first time.

Publication Types:
Review

PMID: 1373068 [PubMed - indexed for MEDLINE]