Chs6p-dependent anterograde transport of Chs3p from the chitosome to the plasma membrane in Saccharomyces cerevisiae.
Chitin synthase III (CSIII), an enzyme required to form a chitin ring in the nascent division septum of Saccharomyces cerevisiae, may be transported to the cell surface in a regulated manner. Chs3p, the catalytic subunit of CSIII, requires the product of CHS6 to be transported to or activated at the cell surface. We find that chs6Delta strains have morphological abnormalities similar to those of chs3 mutants. Subcellular fractionation and indirect immunofluorescence indicate that Chs3p distribution is altered in chs6 mutant cells. Order-of-function experiments using end4-1 (endocytosis-defective) and chs6 mutants indicate that Chs6p is required for anterograde transport of Chs3p from an internal endosome-like membrane compartment, the chitosome, to the plasma membrane. As a result, chs6 strains accumulate Chs3p in chitosomes. Chs1p, a distinct chitin synthase that acts during or after cell separation, is transported normally in chs6 mutants, suggesting that Chs1p and Chs3p are independently packaged during protein transport through the late secretory pathway.
Ziman
M
M
Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California 94720, USA.
Chuang
J S
JS
Tsung
M
M
Hamamoto
S
S
Schekman
R
R
D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D002687:Chitin Synthase / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D011506:Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D012995:Solubility; D013347:Subcellular Fractions
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; D011506:Proteins; C082266:SLA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D002687:Chitin Synthase