A trans-acting factor required for cAMP-induced gene expression in Dictyostelium is regulated developmentally and induced by cAMP.
We have identified a nuclear activity that binds specifically to a GT-rich sequence or G-box shown previously by use of deletion analysis to be required for cAMP and for developmentally induced expression of the prestalk gene pst-cathepsin (CP2). We show that the insertion of an oligonucleotide that contains the CP2 G-box restores regulated expression whereas the insertion of oligonucleotides that contain mutations in some of the G residues does not. Moreover, the mutant oligonucleotides do not compete for binding of the factor to the wild-type sequence. The activity of the G-box binding factor (GBF) is regulated developmentally with induction of activity occurring at the time of induction of pst-cathepsin expression. In a single-cell culture, GBF activity is inducible by cAMP, and its appearance is inhibited by cycloheximide, which suggests that the factor, or a protein component required for binding of the factor, is directly induced by cAMP and may be the rate-limiting factor required for cAMP induction of pst-cathepsin expression. Models for cAMP induction of prestalk genes are described.
Hjorth
A L
AL
Department of Biology, University of California, San Diego, La Jolla 92093.
Khanna
N C
NC
Firtel
R A
RA
D001483:Base Sequence; D002403:Cathepsins / Q000096:biosynthesis; D000242:Cyclic AMP / Q000494:pharmacology*; D004023:Dictyostelium / Q000235:genetics* / Q000254:growth & development; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D015696:Gene Products, tat; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*
D005656:Fungal Proteins; D015696:Gene Products, tat; D014157:Transcription Factors; D000242:Cyclic AMP; D002403:Cathepsins