In:
Eukaryotic Cell, American Society for Microbiology, Vol. 1, No. 4 ( 2002-08), p. 558-567
Abstract:
The Schizosaccharomyces pombe fbp1 gene, encoding fructose-1,6-bisphosphatase, is transcriptionally repressed by glucose. Mutations that confer constitutive fbp1 transcription identify git (glucose-insensitive transcription) genes that encode components of a cyclic AMP (cAMP) signaling pathway required for adenylate cyclase activation. Four of these genes encode the three subunits of a heterotrimeric G protein ( gpa2 , git5 , and git11 ) and a G protein-coupled receptor ( git3 ). Three additional genes, git1 , git7 , and git10 , act in parallel to or downstream from the G protein genes. Here, we describe the cloning and characterization of the git7 gene. The Git7p protein is a member of the Saccharomyces cerevisiae Sgt1p protein family. In budding yeast, Sgt1p associates with Skp1p and plays an essential role in kinetochore assembly, while in Arabidopsis , a pair of SGT1 proteins have been found to be involved in plant disease resistance through an interaction with RAR1. Like S . cerevisiae Sgt1p, Git7p is essential, but this requirement appears to be due to roles in septation and cell wall integrity, which are unrelated to cAMP signaling, as S . pombe cells lacking either adenylate cyclase or protein kinase A are viable. In addition, git7 mutants are sensitive to the microtubule-destabilizing drug benomyl, although they do not display a chromosome stability defect. Two alleles of git7 that are functional for cell growth and septation but defective for glucose-triggered cAMP signaling encode proteins that are altered in the highly conserved carboxy terminus. The S . cerevisiae and human SGT1 genes both suppress git7-93 but not git7-235 for glucose repression of fbp1 transcription and benomyl sensitivity. This allele-specific suppression indicates that the Git7p/Sgt1p proteins may act as multimers, such that Git7-93p but not Git7-235p can deliver the orthologous proteins to species-specific targets. Our studies suggest that members of the Git7p/Sgt1p protein family may play a conserved role in the regulation of adenylate cyclase activation in S . pombe , S . cerevisiae , and humans.
Type of Medium:
Online Resource
ISSN:
1535-9778
,
1535-9786
DOI:
10.1128/EC.1.4.558-567.2002
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2002
detail.hit.zdb_id:
2071564-X
SSG:
12
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