| Alanine scanning mutagenesis of the switch I region in the ATPase site of Dictyostelium discoideum myosin II. | |
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MedLine Citation:
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PMID: 9369475 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In order to determine the functional roles of the conserved sequence (NXNSSRFG) of the "switch I" loop (residues 233-240 in Dictyostelium myosin II), alanine scanning mutagenesis was performed on Dictyostelium myosin II. N233A and S237A mutant myosins did not bind a fluorescent analog of ADP, mant-deoxyADP, at the low concentration range (micromolar and had low level of ATPase activities. They were nonmotile when examined by the in vitro motility assay. Dictyostelium cells expressing these myosins showed worse phenotypes than that of myosin-null cells. In contrast to these mutant myosins, R238A myosin tightly bound mant-deoxyADP. However, the mutant had a defect in the ATP hydrolysis step and exhibited the lowest ATPase activities among the mutants examined here. The R238A myosin was nonmotile. R238C or R238H mutations, which mimic the Usher syndrome mutations, generated myosins with similar functional defects to those of the R238A mutation. Cells expressing the R238A myosin exhibited the phenotype similar to that of the myosin-null cells. N235A, S236A, F239A, and G240A myosins retained moderate levels of ATPase activities and could drive sliding of actin filaments at various speeds. Phenotypes of cells expressing them were very similar to that of the wild-type cells. Taken together, these results suggest that side chains of N233 and S237 may play essential roles in holding a nucleotide in the ATPase pocket and that R238 may play crucial roles in the ATP hydrolysis step, while those of the other residues in the switch I loop are not essential for the process. |
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Authors:
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T Shimada; N Sasaki; R Ohkura; K Sutoh |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biochemistry Volume: 36 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1997 Nov |
Date Detail:
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Created Date: 1997-12-19 Completed Date: 1997-12-19 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 14037-43 Citation Subset: IM |
Affiliation:
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Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo 153, Japan. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Diphosphate
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analogs & derivatives,
metabolism Adenosine Triphosphatases / genetics, metabolism* Alanine / genetics Animals Anthranilic Acids / metabolism Binding Sites DNA Mutational Analysis Deafness / genetics Dictyostelium / cytology, enzymology*, genetics Humans Hydrolysis Locomotion Motion Mutagenesis Myosins / genetics, metabolism* Recombinant Proteins / metabolism |
| Chemical | |
Reg. No./Substance:
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0/2'-deoxy-3'-(N-methylanthraniloyl)adenosine 5'-diphosphate; 0/Anthranilic Acids; 0/Recombinant Proteins; 56-41-7/Alanine; 58-64-0/Adenosine Diphosphate; EC 3.6.1.-/Adenosine Triphosphatases; EC 3.6.4.1/Myosins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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