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Phosphorylation of the myosin regulatory light chain plays a role in motility and polarity during Dictyostelium chemotaxis.

Abstract：

:The myosin regulatory light chain (RLC) of Dictyostelium discoideum is phosphorylated at a single serine site in response to chemoattractant. To investigate the role of the phosphorylation of RLC in both motility and chemotaxis, mutants were generated in which the single phosphorylatable serine was replaced with a nonphosphorylatable alanine. Several independent clones expressing the mutant RLC in the RLC null mutant, mlcR(-), were obtained. These S13A mutants were subjected to high resolution computer-assisted motion analysis to assess the basic motile behavior of cells in the absence of a chemotatic signal, and the chemotactic responsiveness of cells to the spatial, temporal and concentration components of natural cAMP waves. In the absence of a cAMP signal, mutant cells formed lateral pseudopods less frequently and crawled faster than wild-type cells. In a spatial gradient of cAMP, mutant cells chemotaxed more efficiently than wild-type cells. In the front of simulated temporal and natural waves of cAMP, mutant cells responded normally by suppressing lateral pseudopod formation. However, unlike wild-type cells, mutant cells did not lose cellular polarity at the peak and in the back of either wave. Since depolarization at the peak and in the descending phase of the natural wave is necessary for efficient chemotaxis, this deficiency resulted in a decrease in the capacity of S13A mutant cells to track natural cAMP waves relayed by wild-type cells, and in the fragmentation of streams late in mutant cell aggregation. These results reveal a regulatory pathway induced by the peak and back of the chemotactic wave that alters RLC phosphorylation and leads to cellular depolarization. We suggest that depolarization requires myosin II rearrangement in the cortex facilitated by RLC phosphorylation, which increases myosin motor function.

journal_name

J Cell Sci

journal_title

Journal of cell science

authors

Zhang H,Wessels D,Fey P,Daniels K,Chisholm RL,Soll DR

keywords:

subject

Has Abstract

pub_date

2002-04-15 00:00:00

pages

1733-47

issue

Pt 8

eissn

0021-9533

issn

1477-9137

journal_volume

115

pub_type

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Phosphorylation of the myosin regulatory light chain plays a role in motility and polarity during Dictyostelium chemotaxis.