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          Institute: MPI für medizinische Forschung     Collection: Abteilung Biophysik     Display Documents

ID: 22824.0, MPI für medizinische Forschung / Abteilung Biophysik
Stabilization of the actomyosin complex by negative charges on myosin
Translation of Title:Stabilization of the actomyosin complex by negative charges on myosin
Authors:Furch, Marcus; Remmel, Bettina; Geeves, Michael A.; Manstein, Dietmar J.
Date of Publication (YYYY-MM-DD):2000-08-26
Title of Journal:Biochemistry
Journal Abbrev.:Biochem.
Issue / Number:38
Start Page:11602
End Page:11608
Review Status:Peer-review
Audience:Experts Only
Intended Educational Use:No
Abstract / Description:Sequence comparisons of members of the myosin superfamily show a high degree of charge conservation in a surface exposed helix (Dictyostelium discoideum myosin II heavy chain residues S510 to K546). Most myosins display a triplet of acidic residues at the equivalent positions to D. discoideum myosin II residues D530, E531, and Q532. The high degree of charge conservation suggests strong evolutionary constrain and that this region is important for myosin function. Mutations at position E531 were shown to strongly affect actin binding [Giese, K. C., and Spudich, J. A. (1997) Biochemistry 36, 8465-8473]. Here, we used steady-state and transient kinetics to characterize the enzymatic competence of mutant constructs E531Q and Q532E, and their properties were compared with those of a loop 2 mutant with a 20 amino acid insertion containing 12 positive charges (20/+12) [Furch et al. (1998) Biochemistry 37, 6317-6326], double mutant Q532E(20/+12), and the native motor domain constructs. Our results confirm that charge changes at residues 531 and 532 primarily affect actin binding with little change being communicated to the nucleotide pocket. Mutation D531Q reduces actin affinity (KA) 10-fold, while Q532E leads to a 5-fold increase. The observed changes in KA stem almost exclusively from variations in the dissociation rate constant (k-A), with the introduction of a single negative charge at position 532 having the same effect on k-A as the introduction of 12 positive charges in the loop 2 region.
External Publication Status:published
Document Type:Article
Communicated by:Wulf Kaiser
Affiliations:MPI für medizinische Forschung/Abteilung Biophysik/
Identifiers:URI:http://pubs.acs.org:80/journals/bichaw/article.cgi... [Full text]
URI:http://pubs.acs.org:80/journals/bichaw/abstract.cg... [Abstract]
URI:http://pubs.acs.org:80/journals/bichaw/article.cgi... [Fulltext PDF]
DOI:10.1021/bi000985x S0006-2960(00)00985-5
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