The pigP gene, an Aspergillus nidulans ortholog of a human gene involved in down syndrome

Sebastian Pilsyk, Andrzej Paszewski

Author address: 

Institute of Biochemistry and Biophysics PAS, Department of Genetics, Warsaw, Poland


A unique tight sulfate permease mutant sB1pr was used as a recipient strain for cloning and characterization of genes which can complement its phenotype (Pi322;syk et al.). The button phenotype of the mutant is the joint effect of two very specific mutations in the sB promoter and in the nonconserved region of the pigP gene encoding subunit of GPI-N-acetylglucosaminyltransferase (GPI-GnT). A human ortholog of the pigP gene was previously shown to be involved in Down Syndrome (Shibuya et al.). The pigP gene codes for a protein which is responsible for GPI anchoring and is involved in vesicular transport in the endoplasmic reticulum. An impairment of this function may disturb the sorting of membrane proteins, including sulfate permease. Conditional disruption of the pigP gene in the wild-type strain leads to the button phenotype on solid media, similar to that of the sB1pr mutant. However, in contrast to sB1pr, the growth defect of the disruptant is not cured by methionine. The disruptant grows fairly well in liquid minimal medium. It appears, therefore, that the PigP protein is essential for growth only on solid media whereas it is dispensible in liquid medium. Furthermore, the pigP strain shows a different pattern of excreted proteins than the wild type. A 34kDa alkaline serine protease (ALP) is abundantly excreted by the mutant. This protease is the major allergen produced by a number of pathogenic fungi. Pi322;syk S, Natorff R, Sie324;ko M, Paszewski A. (2007) Fungal Genet Biol. 44, 715-25, Shibuya K, Kudoh J, Minoshima S, Kawasaki K, Asakawa S, Shimizu N. (2000) 21q22.2. Biochem Biophys Res Commun. 271, 693-8

abstract No: 


Full conference title: 

    • ECFG 9th (2008)