Key result
Temperature-sensitive arp2 mutation depletes Arp2p and Arc18p subunits from the Arp2/3 complex at restrictive temperatures.
Why the study?
The role of Arp2p in the Arp2/3 complex and its impact on cortical actin patch distribution and function in fission yeast was not fully understood.
The study demonstrates that the Arp2p subunit is essential for the structural integrity of the Arp2/3 complex and cortical actin patch motility in fission yeast.
Answers are grounded in this paper and cite their sources.
arp2-1 disrupts yeast actin patch distribution and complex integrity; leaves open Arp2/3 conservation in higher eukaryotes.
The Arp2/3 complex is an essential component of the yeast actin cytoskeleton that localizes to cortical actin patches. We have isolated and characterized a temperature-sensitive mutant of Schizosaccharomyces pombe arp2 that displays a defect in cortical actin patch distribution. The arp2(+) gene encodes an essential actin-related protein that colocalizes with actin at the cortical actin patch. Sucrose gradient analysis of the Arp2/3 complex in the arp2-1 mutant indicated that the Arp2p and Arc18p subunits are specifically lost from the complex at restrictive temperature. These results are consistent with immunolocalization studies of the mutant that show that Arp2-1p is diffusely localized in the cytoplasm at restrictive temperature. Interestingly, Arp3p remains localized to the cortical actin patch under the same restrictive conditions, leading to the hypothesis that loss of Arp2p from the actin patch affects patch motility but does not severely compromise its architecture. Analysis of the mutant Arp2 protein demonstrated defects in ATP and Arp3p binding, suggesting a possible model for disruption of the complex.
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Morrell‐Falvey et al. (1999) studied Yeast actin cytoskeleton defects. arp2-1 temperature-sensitive mutant vs. Permissive temperature / wild-type was evaluated on Cortical actin patch distribution and Arp2/3 complex assembly. A temperature-sensitive mutant of Schizosaccharomyces pombe arp2 causes specific loss of Arp2p and Arc18p subunits from the Arp2/3 complex at restrictive temperatures.
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