A septin from the filamentous fungus A. nidulans induces atypical pseudohyphae in the budding yeast S. cerevisiae.
BACKGROUND
Septins, novel cytoskeletal proteins, form rings at the bases of emerging round buds in yeasts and at the bases of emerging elongated hyphal initials in filamentous fungi.


RESULTS
When introduced into the yeast Saccharomyces cerevisiae, the septin AspC from the filamentous fungus Aspergillus nidulans induced highly elongated atypical pseudohyphae and spore-producing structures similar to those of hyphal fungi. AspC induced atypical pseudohyphae when S. cerevisiae pseudohyphal or haploid invasive genes were deleted, but not when the CDC10 septin gene was deleted. AspC also induced atypical pseudohyphae when S. cerevisiae genes encoding Cdc12-interacting proteins Bem4, Cla4, Gic1 and Gic2 were deleted, but not when BNI1, a Cdc12-interacting formin gene, was deleted. AspC localized to bud and pseudohypha necks, while its S. cerevisiae ortholog, Cdc12, localized only to bud necks.


CONCLUSIONS
Our results suggest that AspC competes with Cdc12 for incorporation into the yeast septin scaffold and once there alters cell shape by altering interactions with the formin Bni1. That introduction of the A. nidulans septin AspC into S. cerevisiae induces a shift from formation of buds to formation of atypical pseudohyphae suggests that septins play an important role in the morphological plasticity of fungi.
Lindsey
Rebecca
R
Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America.
Ha
Youngsil
Y
Momany
Michelle
M
D000199:Actins / Q000737:chemistry; D001233:Aspergillus nidulans / Q000235:genetics*; D003599:Cytoskeleton / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006579:Heterozygote; D025301:Hyphae / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D058112:Septins / Q000235:genetics* / Q000378:metabolism*
D000199:Actins; C105191:Bni1 protein, S cerevisiae; D008565:Membrane Proteins; D008840:Microfilament Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; C512892:CDC10 protein, S cerevisiae; D020558:GTP Phosphohydrolases; D058112:Septins