Biochemical analysis of Dbf4-dependent kinase in Aspergillus nidulans.

Bernadette Connors, Jennifer Line, Morgan Campbell, and Steven James.

Author address: 

Department of Biology, Gettysburg College, Gettysburg. PA 1732


In the fungus Aspergillus nidulans, nimO and cdc7 encode the regulatory and catalytic subunits of the conserved eukaryotic Dbf4-dependent kinase (DDK). In budding yeast, dbf4p escorts cdc7p to origins of replication, and origin unwinding is triggered through phosphorylation of pre-RC components by cdc7p. Dbf4p is subsequently targeted for destruction by the anaphase promoting complex through D-box motifs found in its amino terminus, thus preventing reinitiation of DNA synthesis. In Aspergillus, the temperature sensitive lethality of the nimO18 mutation can be partially suppressed by mutations in two genes, snoA and snoB (suppressor of nimO). As one approach to investigate DDK function we generated epitope tagged alleles of both cdc7 (HA3::cdc7) and nimO (HM2::nimO). Standard immunoblotting techniques have shown that HA3::cdc7p is a phosphoprotein that is differentially phosphorylated through the cell cycle. Preliminary results indicate this phosphorylation occurs in either a nimO- or snoA-dependent manner and current efforts include a detailed examination of HA3::cdc7p in both nimO18 and snoA mutant backgrounds. HM2::nimOp is also a phosphoprotein and our current efforts include examining nimOp turnover and phosphorylation through the cell cycle in strains that harbor mutations in the two N-terminal D-boxes. Supported by NSF-RUI #01-14446 to SJ

abstract No: 


Full conference title: 

23rd Fungal Genetics Conference
    • Fungal Genetics Conference 23rd (2002)