Rod mutations associated with MYH9-related disorders disrupt nonmuscle myosin-IIA assembly

MYH9-related disorders are autosomal dominant syndromes, variably affecting platelet formation, hearing, and kidney function, and result from mutations in the human nonmuscle myosin-IIA heavy chain gene. To understand the mechanisms by which mutations in the rod region disrupt nonmuscle myosin-IIA f...

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Bibliographic Details
Published in:Blood 2005-01, Vol.105 (1), p.161-169
Main Authors: Franke, Josef D., Dong, Fan, Rickoll, Wayne L., Kelley, Michael J., Kiehart, Daniel P.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Circular Dichroism
DNA Glycosylases - genetics
DNA Glycosylases - metabolism
DNA Glycosylases - ultrastructure
Hematologic and hematopoietic diseases
Medical sciences
Microscopy, Electron
Mutation - genetics
Nonmuscle Myosin Type IIA - chemistry
Nonmuscle Myosin Type IIA - metabolism
Platelet diseases and coagulopathies
Retinal Rod Photoreceptor Cells - metabolism
Salts - pharmacology
Temperature
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Summary:MYH9-related disorders are autosomal dominant syndromes, variably affecting platelet formation, hearing, and kidney function, and result from mutations in the human nonmuscle myosin-IIA heavy chain gene. To understand the mechanisms by which mutations in the rod region disrupt nonmuscle myosin-IIA function, we examined the in vitro behavior of 4 common mutant forms of the rod (R1165C, D1424N, E1841K, and R1933Stop) compared with wild type. We used negative-stain electron microscopy to analyze paracrystal morphology, a model system for the assembly of individual myosin-II molecules into bipolar filaments. Wild-type tail fragments formed ordered paracrystal arrays, whereas mutants formed aberrant aggregates. In mixing experiments, the mutants act dominantly to interfere with the proper assembly of wild type. Using circular dichroism, we find that 2 mutants affect the α-helical coiled-coil structure of individual molecules, and 2 mutants disrupt the lateral associations among individual molecules necessary to form higher-order assemblies, helping explain the dominant effects of these mutants. These results demonstrate that the most common mutations in MYH9, lesions in the rod, cause defects in nonmuscle myosin-IIA assembly. Further, the application of these methods to biochemically characterize rod mutations could be extended to other myosins responsible for disease.
ISSN:0006-4971
1528-0020
DOI:10.1182/blood-2004-06-2067