The phosphoinositide phosphatase Sjl2 is recruited to cortical actin patches in the control of vesicle formation and fission during endocytosis

Mol Cell Biol. 2005 Apr;25(8):2910-23. doi: 10.1128/MCB.25.8.2910-2923.2005.

Abstract

The Saccharomyces cerevisiae synaptojanin-like proteins (Sjl1, Sjl2, and Sjl3) are phosphoinositide (PI) phosphatases that regulate PI metabolism in the control of actin organization and membrane trafficking. However, the primary sites of action for each of the yeast synaptojanin-like proteins remain unclear. In this study, we show that Sjl2 is localized to cortical actin patches, sites of endocytosis. Cortical recruitment of Sjl2 requires the actin patch component Abp1. Consistent with this, the SH3 domain-containing protein Abp1 physically associates with Sjl2 through its proline-rich domain. Furthermore, abp1Delta mutations confer defects resembling loss of SJL2; sjl1Delta abp1Delta double-mutant cells exhibit invaginated plasma membranes and impaired endocytosis, findings similar to those for sjl1Delta sjl2Delta mutant cells. Thus, Abp1 acts as an adaptor protein in the localization or concentration of Sjl2 during late stages of endocytic vesicle formation. Overexpression of the Hip1-related protein Sla2 delayed the formation of extended plasma membrane invaginations in sjl2ts cells, indicating that Sla2 may become limiting or misregulated in cells with impaired PI phosphatase activity. Consistent with this, the cortical actin patch protein Sla2 is mislocalized in sjl1Delta sjl2Delta mutant cells. Together, our studies suggest that PI metabolism by the synaptojanin-like proteins coordinately directs actin dynamics and membrane invagination, in part by regulation of Sla2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Carrier Proteins / metabolism
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism
  • Cytoskeletal Proteins
  • Endocytosis / physiology*
  • Microfilament Proteins / analysis
  • Microfilament Proteins / genetics
  • Microfilament Proteins / physiology
  • Phosphatidylinositols / metabolism*
  • Phosphoric Monoester Hydrolases / analysis
  • Phosphoric Monoester Hydrolases / genetics
  • Phosphoric Monoester Hydrolases / metabolism*
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / analysis
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology
  • Sequence Deletion
  • Transport Vesicles / chemistry
  • Transport Vesicles / physiology*

Substances

  • ABP1 protein, S cerevisiae
  • Actins
  • Carrier Proteins
  • Cytoskeletal Proteins
  • Microfilament Proteins
  • Phosphatidylinositols
  • SLA2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • INP51 protein, S cerevisiae
  • INP52 protein, S cerevisiae
  • INP53 protein, S cerevisiae
  • Phosphoric Monoester Hydrolases