The unconventional myosin encoded by the myoA gene plays a role in Dictyostelium motility

The myoA gene of Dictyostelium is a member of a gene family of unconventional myosins. The myosin Is share homologous head and basic domains, but the myoA gene product lacks the glycine-, proline-, alanine-rich and src homology 3 domains typical of several of the other myosin Is. A mutant strain of...

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Bibliographic Details
Published in:Molecular biology of the cell 1993-02, Vol.4 (2), p.233-246
Main Authors: TITUS, M. A, WESSELS, D, SPUDICH, J. A, SOLL, D
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Biological and medical sciences
Cell Movement
Chemotaxis
Classical genetics, quantitative genetics, hybrids
Cyclic AMP - physiology
Dictyostelium - genetics
Dictyostelium - physiology
DNA, Fungal - genetics
Fundamental and applied biological sciences. Psychology
Gene Expression
Genes, Fungal
Genetics of eukaryotes. Biological and molecular evolution
Molecular Sequence Data
Mutagenesis, Insertional
Myosins - genetics
Myosins - physiology
Oligodeoxyribonucleotides - chemistry
Protozoa
RNA, Fungal - genetics
RNA, Messenger - genetics
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Summary:The myoA gene of Dictyostelium is a member of a gene family of unconventional myosins. The myosin Is share homologous head and basic domains, but the myoA gene product lacks the glycine-, proline-, alanine-rich and src homology 3 domains typical of several of the other myosin Is. A mutant strain of Dictyostelium lacking a functional myoA gene was produced by gene targeting, and the motility of this strain in buffer and a spatial gradient of the chemoattractant cyclic AMP was analyzed by computer-assisted methods. The myoA- cells have a normal elongate morphology in buffer but exhibit a decrease in the instantaneous velocity of cellular translocation, an increase in the frequency of lateral pseudopod formation, and an increase in turning. In a spatial gradient, in which the frequency of pseudopod formation is depressed, myoA- cells exhibit positive chemotaxis but still turn several times more frequently than control cells. These results demonstrate that the other members of the unconventional myosin family do not fully compensate for the loss of functional myoA gene product. Surprisingly, the phenotype of the myoA- strain closely resembles that of the myoB- strain, suggesting that both play a role in the frequency of pseudopod formation and turning during cellular translocation.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.4.2.233