Regulation of clathrin adaptor function in endocytosis: novel role for the SAM domain.
During clathrin-mediated endocytosis, adaptor proteins play central roles in coordinating the assembly of clathrin coats and cargo selection. Here we characterize the binding of the yeast endocytic adaptor Sla1p to clathrin through a variant clathrin-binding motif that is negatively regulated by the Sla1p SHD2 domain. The crystal structure of SHD2 identifies the domain as a sterile alpha-motif (SAM) domain and shows a propensity to oligomerize. By co-immunoprecipitation, Sla1p binds to clathrin and self-associates in vivo. Mutations in the clathrin-binding motif that abolish clathrin binding and structure-based mutations in SHD2 that impede self-association result in endocytosis defects and altered dynamics of Sla1p assembly at the sites of endocytosis. These results define a novel mechanism for negative regulation of clathrin binding by an adaptor and suggest a role for SAM domains in clathrin-mediated endocytosis.
Di Pietro
Santiago M
SM
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA. santiago.dipietro@colostate.edu
Cascio
Duilio
D
Feliciano
Daniel
D
Bowie
James U
JU
Payne
Gregory S
GS
D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002966:Clathrin / Q000737:chemistry / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D003598:Cytoskeletal Proteins; C082265:SLA1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins