Role of septins and the exocyst complex in the function of hydrolytic enzymes responsible for fission yeast cell separation.
Cell separation in Schizosaccharomyces pombe is achieved by the concerted action of the Eng1 endo-beta-1,3-glucanase and the Agn1 endo-alpha-1,3-glucanase, which are transported to the septum and localize to a ringlike structure that surrounds the septum. The requirements for the correct localization of both hydrolases as a ring were analyzed using green fluorescent protein fusion proteins. Targeting to the septum required a functional exocyst, because both proteins failed to localize correctly in sec8-1 or exo70delta mutants, suggesting that Agn1 and Eng1 might be two of the cargo proteins present in the vesicles that accumulate in exocyst mutants. Septins and Mid2 were also required for correct formation of a ring. In their absence, Eng1 and Agn1 were found in a disk-like structure that spanned the septum, rather than in a ring. Even though septin and mid2delta mutants have a cell separation defect, the septum and the distribution of linear beta-1,3-glucans were normal in these cells, suggesting that mislocalization of Eng1 and Agn1 might be the reason underlying the failure to separate efficiently. Thus, one of the functions of the septin ring would be to act as a positional marker for the localization of hydrolytic proteins to the medial region.
Martín-Cuadrado
Ana Belén
AB
Instituto de Microbiología Bioquímica, Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Cientificas/Universidad de Salamanca, 37007 Salamanca, Spain.
Morrell
Jennifer L
JL
Konomi
Mami
M
An
Hanbing
H
Petit
Claudia
C
Osumi
Masako
M
Balasubramanian
Mohan
M
Gould
Kathleen L
KL
Del Rey
Francisco
F
de Aldana
Carlos R Vázquez
CR
D048749:Cytokinesis / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D046529:Microscopy, Electron, Transmission; D046912:Multiprotein Complexes / Q000502:physiology; D009154:Mutation; D012568:Schizosaccharomyces / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000502:physiology*; D047071:beta-Glucans / Q000378:metabolism
D046912:Multiprotein Complexes; D029702:Schizosaccharomyces pombe Proteins; D047071:beta-Glucans; C033363:beta-1,3-glucan; D006026:Glycoside Hydrolases; D019204:GTP-Binding Proteins