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Coiled‐coil stutter and link segments in keratin and other intermediate filament molecules: A computer modeling study
Author(s) -
North Anthony C. T.,
Steinert Peter M.,
Parry David A. D.
Publication year - 1994
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340200207
Subject(s) - coiled coil , intermediate filament , protein filament , sequence (biology) , substructure , heptad repeat , classification of discontinuities , biophysics , crystallography , protein structure , chemistry , peptide sequence , physics , biology , cytoskeleton , nuclear magnetic resonance , biochemistry , mathematics , mathematical analysis , structural engineering , gene , engineering , cell
Structural discontinuities have previously been identified in four regions of the coiled‐coil rod domain structure present in intermediate filament (IF) protein molecules. These include a point at which a phase shift occurs in the heptad periodicity characteristic of the sequence of polar and apolar residues in α‐helical coiled‐coils, and three links that lack a heptad substructure. We have studied these regions by computer‐based molecular modeling and comparative sequence analysis and conclude that the phasing discontinuity can be accommodated without significant distortion of the overall double‐helical chain conformation; the L2 link has a similar conformation in all different types of IF molecules, a favorable conformation being one in which the two strands wrap tightly around each other; the L12 links vary in length between different IF types but contain important sequence similarities suggestive of a partial β structure; the L1 links show larger variations in length, a lower degree of similarity, and probably diverse structures. Variations in the overall charges of the different links suggest that ionic interactions may playa significant role in filament assembly. The results also have general significance for other α‐fibrous proteins in which either the characteristic heptad phasing undergoes a discontinuity or where a short non‐coiled‐coil sequence occurs within a coiled‐coil rod domain structure. © 1994 Wiley‐Liss, Inc.