Protein-protein interactions governing septin heteropentamer assembly and septin filament organization in Saccharomyces cerevisiae.
Mitotic yeast (Saccharomyces cerevisiae) cells express five related septins (Cdc3, Cdc10, Cdc11, Cdc12, and Shs1) that form a cortical filamentous collar at the mother-bud neck necessary for normal morphogenesis and cytokinesis. All five possess an N-terminal GTPase domain and, except for Cdc10, a C-terminal extension (CTE) containing a predicted coiled coil. Here, we show that the CTEs of Cdc3 and Cdc12 are essential for their association and for the function of both septins in vivo. Cdc10 interacts with a Cdc3-Cdc12 complex independently of the CTE of either protein. In contrast to Cdc3 and Cdc12, the Cdc11 CTE, which recruits the nonessential septin Shs1, is dispensable for its function in vivo. In addition, Cdc11 forms a stoichiometric complex with Cdc12, independent of its CTE. Reconstitution of various multiseptin complexes and electron microscopic analysis reveal that Cdc3, Cdc11, and Cdc12 are all necessary and sufficient for septin filament formation, and presence of Cdc10 causes filament pairing. These data provide novel insights about the connectivity among the five individual septins in functional septin heteropentamers and the organization of septin filaments.
Versele
Matthias
M
Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
Gullbrand
Björn
B
Shulewitz
Mark J
MJ
Cid
Victor J
VJ
Bahmanyar
Shirin
S
Chen
Raymond E
RE
Barth
Patrick
P
Alber
Tom
T
Thorner
Jeremy
J
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D020558:GTP Phosphohydrolases; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D051304:Profilins; D020033:Protein Isoforms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D016415:Sequence Alignment; D014157:Transcription Factors
C099504:CDC12 protein, S cerevisiae; C086662:CDC3 protein, S cerevisiae; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D051304:Profilins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C061178:cdc10 protein, S pombe; C512892:CDC10 protein, S cerevisiae; D020558:GTP Phosphohydrolases