title: Stabilizing the central part of tropomyosin increases the bending stiffness of the thin filament.
abstract: A two-beam optical trap was used to measure the bending stiffness of F-actin and reconstructed thin filaments. A dumbbell was formed by a filament segment attached to two beads that were held in the two optical traps. One trap was static and held a bead used as a force transducer, whereas an acoustooptical deflector moved the beam holding the second bead, causing stretch of the dumbbell. The distance between the beads was measured using image analysis of micrographs. An exact solution to the problem of bending of an elastic filament attached to two beads and subjected to a stretch was used for data analysis. Substitution of noncanonical residues in the central part of tropomyosin with canonical ones, G126R and D137L, and especially their combination, caused an increase in the bending stiffness of the thin filaments. The data confirm that the effect of these mutations on the regulation of actin-myosin interactions may be caused by an increase in tropomyosin stiffness.
authors.affiliation: Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia.
authors.forename: Salavat R
authors.initials: SR
authors.lastname: Nabiev
authors.affiliation: Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia.
authors.forename: Denis A
authors.initials: DA
authors.lastname: Ovsyannikov
authors.affiliation: Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia.
authors.forename: Galina V
authors.initials: GV
authors.lastname: Kopylova
authors.affiliation: Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia.
authors.forename: Daniil V
authors.initials: DV
authors.lastname: Shchepkin
authors.affiliation: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia; Department of Biochemistry, School of Biology, Moscow State University, Moscow, Russia.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Matyushenko
authors.affiliation: Institute of Mechanics, Moscow State University, Moscow, Russia.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Koubassova
authors.affiliation: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia; A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
authors.forename: Dmitrii I
authors.initials: DI
authors.lastname: Levitsky
authors.affiliation: Institute of Mechanics, Moscow State University, Moscow, Russia.
authors.forename: Andrey K
authors.initials: AK
authors.lastname: Tsaturyan
authors.affiliation: Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia. Electronic address: s.bershitsky@iip.uran.ru.
authors.forename: Sergey Y
authors.initials: SY
authors.lastname: Bershitsky
mesh_terms: D000199:Actins / Q000737:chemistry*; D000818:Animals; D004548:Elasticity; D006801:Humans; D008856:Microscopy, Fluorescence; D018482:Muscle, Skeletal; D052898:Optical Tweezers; D011487:Protein Conformation; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D014335:Tropomyosin / Q000737:chemistry* / Q000235:genetics
chemical_list: D000199:Actins; D011994:Recombinant Proteins; C490775:TPM1 protein, human; D014335:Tropomyosin