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J. Bacteriol., 12 1997, 7653-7662, Vol 179, No. 24
J Ishiguro, A Saitou, A Duran and JC Ribas
The Schizosaccharomyces pombe cps1-12 (for chlorpropham supersensitive)
mutant strain was originally isolated as hypersensitive to the spindle
poison isopropyl N-3-chlorophenyl carbamate (chlorpropham) (J. Ishiguro and
Y. Uhara, Jpn. J. Genet. 67:97-109, 1992). We have found that the cps1-12
mutation also confers (i) hypersensitivity to the immunosuppressant
cyclosporin A (CsA), (ii) hypersensitivity to the drug papulacandin B,
which specifically inhibits 1,3-beta-D-glucan synthesis both in vivo and in
vitro, and (iii) thermosensitive growth at 37 degrees C. Under any of these
restrictive treatments, cells swell up and finally lyse. With an osmotic
stabilizer, cells do not lyse, but at 37 degrees C they become
multiseptated and multibranched. The cps1- 12 mutant, grown at a
restrictive temperature, showed an increase in sensitivity to lysis by
enzymatic cell wall degradation, in in vitro 1,3-beta-D-glucan synthase
activity (173% in the absence of GTP in the reaction), and in cell wall
biosynthesis (130% of the wild-type amount). Addition of Ca2+ suppresses
hypersensitivity to papulacandin B and septation and branching phenotypes.
All of these data suggest a relationship between the cps1+ gene and cell
wall synthesis. A DNA fragment containing the cps1+ gene was cloned, and
sequence analysis indicated that it encodes a predicted membrane protein of
1,729 amino acids with 15 to 16 transmembrane domains. S. pombe cps1p has
overall 55% sequence identity with Fks1p or Fks2p, proposed to be catalytic
or associated subunits of Saccharomyces cerevisiae 1,3-beta-D-glucan
synthase. Thus, the cps1+ product might be a catalytic or an associated
copurifying subunit of the fission yeast 1,3-beta-D-glucan synthase that
plays an essential role in cell wall synthesis.
Copyright © 1997, American Society for Microbiology
cps1+, a Schizosaccharomyces pombe gene homolog of Saccharomyces cerevisiae FKS genes whose mutation confers hypersensitivity to cyclosporin A and papulacandin B
Department of Biology, Faculty of Science, Konan University, Okamoto, Kobe, Japan.
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