The severe growth defects of two A.nidulans strains expressing RpdA with two point-mutations of catalytically essential residues within the N-terminal domain confirmed, that a loss of catalytic RpdA activity is responsible for defects in growth and sporulation of A.nidulans strains depleted in RpdA. Additionally, the proper targeting of RpdA into the nucleus is independent on the catalytic HDAC activity, since Venus-tagged, mutated RpdA was detected in the nuclei of the corresponding expression strains. Expression of hsHDAC2 failed in A.nidulans mutants depleted for endogenous RpdA, thus, it is currently not possible to make any statement concerning the ability of a possible complementation. However, due to the fact that hsHDAC1 was successfully expressed in A. nidulans, but was not able to complement for depleted RpdA, substantiate the assumption, that indeed fungal-specific motifs of RpdA might be essential for its biological function in filamentous fungi.

Silke Katharina Gross, M.Sc., M.Sc. Molecular Cell- and Developmental Biology and Microbiology - Leopold Franzens University of Innsbruck; Innsbruck, Tyrol, Austria. Study Director Assistance - Eurofins BioPharma Product Testing GmbH; Munich, Bavaria, Germany