Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSRegulation of glycolysis and gluconeogenesis by antisense transcription in Aspergillus nidulans? Michael Hynes 1 , Koon Ho Wong 2 , Sandra Murray 1 . 1)Dept Gen, Univ Melbourne, Parkville, Victoria, Australia; 2) Dept. of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, MA.The last step in glycolysis is carried out by pyruvate kinase, encoded by pkiA, converting phospho-enol-pyruvate to pyruvate for metabolism tooxaloacetate and acetyl-CoA. The key step in gluconeogenesis is conversion of oxaloacetate to phospho-enol-pyruvate by PEP carboxykinase, encoded byacuF. Simultaneous activity of these enzymes would generate a nasty futile cycle. A number of observations suggests that control of the expression ofthese two genes involves activation of sense transcription and negative control by activation of antisense transcription. For pkiA, ChIP studies have foundbinding of the gluconeogenic activators AcuK and AcuM and of the acetate dependent FacB activator in the downstream region. Cognate binding sites areconserved in filamentous ascomycetes. RNA Seq, polII ChIP and RT-PCR analysis indicates antisense transcription during growth on acetate or proline ascarbon sources. Old data (de Graaf, van den Broek, Visser; Cur. Genetics 13: 315, 1988) showed that transformation of a construct lacking these 3’ sitesresulted in inappropriate pkiA expression on acetate. In response to growth on gluconeogenic carbon sources, the acuF gene is activated by AcuK andAcuM binding to sites in the 5’ upstream region. Studies with an acuF-lacZ gene fusion indicate positive control by AcuK and AcuM but a loss of the glucoserepression observed in Northerns suggesting negative regulation acting via 3’ sequences in response to growth on glycolytic carbon sources. Support forthis is provided by transcription studies. Modulation of the balance between the opposing activities of these two gene products is proposed to result fromtranscriptional interference involving collision of RNA polymerase molecules.44