Assembly mechanisms of the bacterial cytoskeletal protein FilP.

Javadi A, Söderholm N, Olofsson A, Flärdh K, Sandblad L

Life Sci. Alliance 2 (3) e201800290 [2019-06-00; online 2019-06-26]

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.

Cryo-EM [Collaborative]

PubMed 31243049

DOI 10.26508/lsa.201800290

Crossref 10.26508/lsa.201800290

pii: 2/3/e201800290
pmc: PMC6599971