The G protein beta subunit Gpb1 of Schizosaccharomyces pombe is a negative regulator of sexual development.
A Schizosaccharomyces pombe homolog of mammalian genes encoding G protein beta subunits, gpb1+, was cloned by the polymerase chain reaction using primer pairs that correspond to sequences conserved in several G beta genes of other species followed by screening of genomic and cDNA libraries. The gpb1 gene encodes 317 amino acids that show 47% homology with human G beta 1 and G beta 2 and 40% homology with Saccharomyces cerevisiae G beta protein. Disruption of the gpb1 gene indicated that this gene is not required for vegetative cell growth. However, gpb1-disrupted haploid cells mated and sporulated faster than wild-type cells, both in sporulation (MEA) and in complex medium (YE): when examined 23 h after transfer to sporulation medium, 35% of gpb1-disrupted haploid pairs had undergone conjugation and sporulation, whereas only 3-5% of wild-type haploid pairs had done so. Overexpression of the gpb1 gene suppressed this facilitated conjugation and sporulation phenotype of gpb1-disrupted cells but did not cause any obvious effect in wild-type cells. Co-disruption of one of the two S. pombe G alpha-subunit genes, gpa2, in the gpb1-disrupted cells did not change the accelerated conjugation and sporulation phenotype of the gpb1- cells. However, co-disruption of the ras1 gene abolished the gpb1- phenotype. These results suggest that Gpb1 is a negative regulator of conjugation and sporulation that apparently works upstream of Ras1 function in S. pombe. The possible relationship of Gpb1 to two previously identified, putative G alpha proteins of S. pombe is discussed.
Kim
D U
DU
Cell Cycle & Signal Research Unit, Korea Research Institute of Bioscience and Biotechnology, KIST, Taejon, Korea.
Park
S K
SK
Chung
K S
KS
Choi
M U
MU
Yoo
H S
HS
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D017931:DNA Primers; D004587:Electrophoresis, Agar Gel; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D005800:Genes, Fungal; D020962:Heterotrimeric GTP-Binding Proteins; D008969:Molecular Sequence Data; D010641:Phenotype; D012568:Schizosaccharomyces / Q000235:genetics* / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000502:physiology
D017931:DNA Primers; D005656:Fungal Proteins; D029702:Schizosaccharomyces pombe Proteins; C101525:git5 protein, S pombe; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins