title: Abnormal movement of tropomyosin and response of myosin heads and actin during the ATPase cycle caused by the Arg167His, Arg167Gly and Lys168Glu mutations in TPM1 gene.
abstract: Amino acid substitutions: Arg167His, Arg167Gly and Lys168Glu, located in a consensus actin-binding site of the striated muscle tropomyosin Tpm1.1 (TM), were used to investigate mechanisms of the thin filament regulation. The azimuthal movement of TM strands on the actin filament and the responses of the myosin heads and actin subunits during the ATPase cycle were studied using fluorescence polarization of muscle fibres. The recombinant wild-type and mutant TMs labelled with 5-IAF, 1,5-IAEDANS-labelled S1and FITC-phalloidin F-actin were incorporated into the ghost muscle fibres to acquire information on the orientation of the probes relative to the fibre axis. The substitutions Arg167Gly and Lys168Glu shifted TM strands into the actin filament centre, whereas Arg167His moved TM towards the periphery of the filament. In the presence of Arg167Gly-TM and Lys168Glu-TM the fraction of actin monomers that were switched on and the number of the myosin heads strongly bound to F-actin were abnormally high even under conditions close to relaxation. In contrast, Arg167His-TM decreased the fraction of switched on actin and reduced the formation of strongly bound myosin heads throughout the ATPase cycle. We concluded that the altered TM-actin contacts destabilized the thin filament and affected the actin-myosin interactions.
authors.affiliation: Institute of Cytology, Tikhoretsky Pr., 4, Saint Petersburg, 194064, Russia. Electronic address: borovikov@incras.ru.
authors.forename: Yurii S
authors.initials: YS
authors.lastname: Borovikov
authors.affiliation: Institute of Cytology, Tikhoretsky Pr., 4, Saint Petersburg, 194064, Russia.
authors.forename: Nikita A
authors.initials: NA
authors.lastname: Rysev
authors.affiliation: Institute of Cytology, Tikhoretsky Pr., 4, Saint Petersburg, 194064, Russia.
authors.forename: Aleksey A
authors.initials: AA
authors.lastname: Chernev
authors.affiliation: Institute of Cytology, Tikhoretsky Pr., 4, Saint Petersburg, 194064, Russia.
authors.forename: Stanislava V
authors.initials: SV
authors.lastname: Avrova
authors.affiliation: Institute of Cytology, Tikhoretsky Pr., 4, Saint Petersburg, 194064, Russia.
authors.forename: Olga E
authors.initials: OE
authors.lastname: Karpicheva
authors.affiliation: Kazimierz Wielki University in Bydgoszcz, Department of Biochemistry and Cell Biology, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Borys
authors.affiliation: Kazimierz Wielki University in Bydgoszcz, Department of Biochemistry and Cell Biology, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Śliwińska
authors.affiliation: Kazimierz Wielki University in Bydgoszcz, Department of Biochemistry and Cell Biology, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Moraczewska
mesh_terms: D000199:Actins / Q000737:chemistry; D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000818:Animals; D001120:Arginine / Q000737:chemistry; D005973:Glutamine / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D008297:Male; D008856:Microscopy, Fluorescence; D009154:Mutation; D009218:Myosins / Q000737:chemistry*; D009711:Nucleotides; D010590:Phalloidine / Q000737:chemistry; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry; D013696:Temperature; D014335:Tropomyosin / Q000737:chemistry* / Q000235:genetics*
chemical_list: D000199:Actins; D009711:Nucleotides; D011994:Recombinant Proteins; D014335:Tropomyosin; D005973:Glutamine; D010590:Phalloidine; D006639:Histidine; D001120:Arginine; D000251:Adenosine Triphosphatases; D009218:Myosins; D008239:Lysine; D005998:Glycine
keywords: Congenital myopathies; F-actin; Fluorescence polarization; Ghost muscle fibres; Myosin; Tropomyosin; Troponin