Regulation of Rho-GEF Rgf3 by the arrestin Art1 in fission yeast cytokinesis.
Bottom Line: Using an Rgf3 conditional mutant and mislocalization experiments, we found that Art1 and Rgf3 are interdependent for localization to the division site.As expected, active Rho1 levels at the division site are reduced in art1∆ and rgf3 mutant cells.Taken together, these data reveal that the arrestin family protein Art1 regulates the protein levels and localization of the Rho-GEF Rgf3, which in turn modulates active Rho1 levels during fission yeast cytokinesis.
Affiliation: Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.Show MeSH
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Mentions: The art1-s34 mutant was isolated in a synthetic lethal/sick screen carried out in a septin-depletion strain along with several genes that are known or predicted components of the cell-integrity pathway (Wu et al., 2010). art1-s34 cells have a mild cell lysis defect (∼5% of asynchronous cells) when grown in minimal medium EMM5S at 30°C (Wu et al., 2010). However, when grown in rich YE5S medium at 25°C, ∼20% of art1-s34 cells lysed (Figure 1, A and B). To further study the role of Art1, we deleted its whole open reading frame and found that cell lysis was similar (∼22%) in art1∆ cells (Figure 1, A and B), which is consistent with the prediction that art1-s34 is a allele (Wu et al., 2010). The lysis phenotype of the art1 mutants resembled that of the Rho-GEF rgf3(lad1-1) mutant (Morrell-Falvey et al., 2005), in which the lysed daughter cells often attach to each other in the shape of “boomerangs” (Figure 1A, arrowheads). Time-lapse imaging of art1∆ cells revealed that lysis occurred during cell separation (Figure 1C and Supplemental Video S1). The lysis phenotype suggests that the plasma membrane and/or the septum at the division site are defective in the art1 mutants.
Affiliation: Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.