Structure and tropomyosin binding properties of the N-terminal capping domain of tropomodulin 1

Norma J Greenfield; Alla S Kostyukova; Sarah E Hitchcock-DeGregori

doi:10.1529/biophysj.104.051128

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Structure and tropomyosin binding properties of the N-terminal capping domain of tropomodulin 1

Journal article

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Structure and tropomyosin binding properties of the N-terminal capping domain of tropomodulin 1

Norma J Greenfield, Alla S Kostyukova and Sarah E Hitchcock-DeGregori

Biophysical journal, Vol.88(1), pp.372-383

01/2005

DOI: https://doi.org/10.1529/biophysj.104.051128

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https://hdl.handle.net/2376/117300

PMCID: PMC1305014

PMID: 15475586

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Abstract

Temperature

Molecular Sequence Data

Sensitivity and Specificity

Actins - chemistry

Tropomodulin

Carrier Proteins - chemistry

Electrophoresis

Muscles - metabolism

Binding Sites

Circular Dichroism

Protein Structure, Tertiary

Amino Acid Sequence

Microfilament Proteins - chemistry

Mutagenesis, Site-Directed

Magnetic Resonance Spectroscopy

Peptides - chemistry

Protein Structure, Secondary

Amino Acid Motifs

Sequence Homology, Amino Acid

DNA - chemistry

Animals

Mutagenesis

Chickens

Protein Binding

Protein Conformation

Mutation

Proteins - chemistry

Tropomyosin - chemistry

Two families of actin regulatory proteins are the tropomodulins and tropomyosins. Tropomodulin binds to tropomyosin (TM) and to the pointed end of actin filaments and "caps" the pointed end (i.e., inhibits its polymerization and depolymerization). Tropomodulin 1 has two distinct actin-capping regions: a folded C-terminal domain (residues 160-359), which does not bind to TM, and a conserved, N-terminal region, within residues 1-92 that binds TM and requires TM for capping activity. NMR and circular dichroism were used to determine the structure of a peptide containing residues 1-92 of tropomodulin (Tmod1(1-92)) and to define its TM binding site. Tmod1(1-92) is mainly disordered with only one helical region, residues 24-35. This helix forms part of the TM binding domain, residues 1-35, which become more ordered upon binding a peptide containing the N-terminus of an alpha-TM. Mutation of L27 to E or G in the Tmod helix reduces TM affinity. Residues 49-92 are required for capping but do not bind TM. Of these, residues 67-75 have the sequence of an amphipathic helix, but are not helical. Residues 55-62 and 76-92 display negative 1H-15N heteronuclear Overhauser enhancements showing they are flexible. The conformational dynamics of these residues may be important for actin capping activity.

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Title: Structure and tropomyosin binding properties of the N-terminal capping domain of tropomodulin 1
Creators: Norma J Greenfield - Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA. greenfie@rwja.umdnj.edu
Alla S Kostyukova
Sarah E Hitchcock-DeGregori
Publication Details: Biophysical journal, Vol.88(1), pp.372-383
Academic Unit: Chemical Engineering and Bioengineering, School of
Publisher: United States
Grant note: GM63257 / NIGMS NIH HHS GM36326 / NIGMS NIH HHS R01 GM063257 / NIGMS NIH HHS R01 GM036326 / NIGMS NIH HHS
Identifiers: 99900548573201842
Language: English
Resource Type: Journal article