Pairwise assembly determines the intrinsic potential for self-organization and mechanical properties of keratin filaments.
Most type I and II keratin genes are spatially and temporally regulated in a pairwise manner in epithelial tissues, where they represent the major structural proteins. Epithelia can be partitioned into simple (single-layered) and complex (multilayered) types. We compared the structural and mechanical properties of natural keratin polymers occurring in complex (K5-K14) and simple (K8-K18) epithelia. The intrinsic properties of these distantly related keratin filaments, whether dispersed or bundled in vitro, were surprisingly similar in all respects when at high polymer concentration. When type I and II assembly partners were switched to give rise to mismatched polymers (K5-K18; K8-K14), the interfilament interactions, which determine the structural and mechanical properties of keratin polymers, were significantly altered. We also show that a K5-K16 polymer exhibits lesser elasticity than K5- K14, which may help explain the inability of K16 to fully rescue the skin blistering characteristic of K14 null mice. The property of self-interaction exhibited by keratin filaments is likely to assist their function in vivo and may account for the relative paucity of cytoplasmic and keratin-specific cross-linkers. Our findings underscore the fundamental importance of pairwise polymerization and have implications for the functional significance of keratin sequence diversity.
Yamada
Soichiro
S
Department of Chemical Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
Wirtz
Denis
D
Coulombe
Pierre A
PA
D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D004548:Elasticity; D004847:Epithelial Cells / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D005782:Gels; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007382:Intermediate Filaments / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D007633:Keratins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012212:Rheology; D013314:Stress, Mechanical; D014170:Transformation, Genetic; D014783:Viscosity
D001704:Biopolymers; D005782:Gels; D011993:Recombinant Fusion Proteins; D007633:Keratins