Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin

Wenise W Wong; Jack H Gerson; Peter A Rubenstein; Emil Reisler

doi:10.1016/S0006-3495(02)75282-X

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Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin

Journal article

Open access

Peer reviewed

Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin

Wenise W Wong, Jack H Gerson, Peter A Rubenstein and Emil Reisler

Biophysical journal, Vol.83(5), pp.2726-2732

11/2002

DOI: 10.1016/S0006-3495(02)75282-X

PMCID: PMC1302357

PMID: 12414705

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Abstract

The N-terminal region in actin has been shown to interact with both myosin and troponin (Tn) during the cross-bridge cycle and in regulation. To study the role of this region in regulation, we used yeast actin mutants with increased and decreased numbers of acidic residues. The mutants included D24A/D25A, with Asp(24) and Asp(25) replaced with alanines; DNEQ, with the substitution of Asp(2) and Glu(4) with their amide analogs; and 4Ac, with Glu(3) and Asp(4) inserted in lieu of Ser(3). In the in vitro motility assay, using reconstituted regulated thin filaments, the sliding speeds of DNEQ, D24A/D25A, and 4Ac were similar at all pCa values. Thus, Ca(2+)-sensitivity of the thin filaments and the inhibitory function of TnI appear to be insensitive to changes in charge (+/-2) at the N-terminus of actin, suggesting little, if any, role of that actin region in regulation. A Ca(2+)-independent conformational change in that region was detected upon troponin binding to actin-Tm via an increase in the fluorescence of a pyrene probe attached to another yeast actin mutant that we used (Cys(1)).

Protein Structure, Tertiary

Troponin - metabolism

Movement

Mutagenesis, Site-Directed

Troponin - chemistry

Actins - metabolism

Models, Molecular

Spectrometry, Fluorescence

Alanine - chemistry

Ions

Calcium - chemistry

Saccharomyces cerevisiae - metabolism

Actins - chemistry

Protein Binding

Fluorescent Dyes - pharmacology

Aspartic Acid - chemistry

Pyrenes - pharmacology

Details

Title: Subtitle: Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin
Creators: Wenise W Wong - Department of Chemistry and Biochemistry, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
Jack H Gerson
Peter A Rubenstein
Emil Reisler
Resource Type: Journal article
Publication Details: Biophysical journal, Vol.83(5), pp.2726-2732
Publisher: United States
DOI: 10.1016/S0006-3495(02)75282-X
PMID: 12414705
PMCID: PMC1302357
ISSN: 0006-3495
eISSN: 1542-0086
Grant note: AR 22031 / NIAMS NIH HHS R01 AR022031 / NIAMS NIH HHS GM 33689 / NIGMS NIH HHS
Language: English
Date published: 11/2002
Academic Unit: Stead Family Department of Pediatrics; Biochemistry and Molecular Biology; Internal Medicine
Record Identifier: 9984024557602771

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