Document Detail

Modulation of actin filament sliding by mutations of the SH2 cysteine in Dictyostelium myosin II.
MedLine Citation:
PMID:  9175779     Owner:  NLM     Status:  MEDLINE    
The cysteine residue called SH2 in the skeletal myosin heavy chain is conserved among various species. Cys 678 in Dictyostelium myosin II is equivalent to SH2 in skeletal myosin. Using the Dictyostelium myosin II heavy chain gene, SH2 was mutated to Gly, Ala, Ser, or Thr. These mutant myosins were expressed in Dictyostelium myosin-null cells. To investigate how these mutations affect the motor functions of myosin, we examined the phenotypes of the transformed cells. We also purified the mutant myosins, and characterized them by measuring the actin-activated MgATPase activity, sliding velocity of actin filaments and force level. All of these mutant myosins complemented the myosin-specific defects of the myosin-null cells. Consistent with these observed phenotypes, all of the purified mutant myosins retained similar actin-activated MgATPase activities and force levels to those of the wild-type myosin (WT). However, the sliding velocities of actin filaments were significantly different (WT > or = Ser > Ala >> Thr > Gly). In particular, the Gly and Thr mutants exhibited a striking decrease in velocity, while the Ser mutant exhibited velocity comparable to that of the wild-type myosin. Thus, mutations of SH2 resulted in uncoupling of ATP hydrolysis and the sliding.
Y Suzuki; R Ohkura; S Sugiura; R Yasuda; K Kinoshita; M Tanokura; K Sutoh
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemical and biophysical research communications     Volume:  234     ISSN:  0006-291X     ISO Abbreviation:  Biochem. Biophys. Res. Commun.     Publication Date:  1997 May 
Date Detail:
Created Date:  1997-06-30     Completed Date:  1997-06-30     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0372516     Medline TA:  Biochem Biophys Res Commun     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  701-6     Citation Subset:  IM    
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Japan.
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MeSH Terms
Actins / metabolism*
Ca(2+) Mg(2+)-ATPase / metabolism
Cysteine / genetics*
Dictyostelium / enzymology,  metabolism*
Mutagenesis, Site-Directed
Myosins / genetics*
src Homology Domains*
Reg. No./Substance:
0/Actins; 52-90-4/Cysteine; EC 3.6.1.-/Ca(2+) Mg(2+)-ATPase; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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