The non-sporulating diploid strain V327 of Saccharomyces cerevisiae was pre
viously isolated in a search for thermosensitive autolytic mutants. This pr
eviously isolated rn a search Tor thermosensitive autolytic mutants. Int st
rain is very efficient at releasing intracellular proteins into the medium
when incubated at high temperatures. The expression of this lytic phenotype
depends on a morphogenetic defect, consisting of the appearance of elongat
ed chains of cells. Transmission electron microscopy revealed a mislocaliza
tion of septa at semi-permissive temperatures and a total lack of septation
together with abnormal cell wail architecture at a non-permissive temperat
ure. The septin-encoding CDC10 gene was cloned by complementation of the pl
eiotropic phenotype of the V327 mutant. Rescue and sequencing of CDC10 alle
les from V327 revealed a point mutation that created a single amino acid ch
ange in a region which is well conserved among septins. This new allele was
named cdc10-11. The construction of a cdc10-11 haploid strain by substitut
ing the CDC10 gene with the rescued allele permitted further genetic analys
es of the mutation and allowed the construction of new homozygous cdc10-11
diploid strains that showed a reduced ability to sporulate. Fusing both the
wild-type and the cdc10-11 alleles to green fluorescent protein (GFP) demo
nstrated that the mutation does not affect the localization of this septin
to the bud neck at the standard growth temperature of 24 degrees C, althoug
h the morphogenetic phenotype at 37 degrees C parallels the disappearance o
f Cdc10-GFP at the ring encircling the septum area.