Sumoylation is required for differentiation and DNA repair in Aspergillus nidulans.

Nak-Jung Kwon, Jeong-Hwa Park, and Suhn-Kee Chae.

Author address: 

BioMed RRC and Division of Life Science, Paichai University, Daejeon 302-735, Korea


SUMO modifies functions of proteins in various ways when attached covalently. The first step of sumoylation is the formation of a thiol ester linkage between the C-terminal glycine of SUMO and an active site cysteine of an SUMO activating enzyme complex, Uba2 and Aos1 (E1). The second step involves the transfer of SUMO to a cysteine in the active site of an SUMO conjugating enzyme of Ubc9 (E2). In the last step, the E2 enzyme may cooperate with an protein ligase (E3) to form an isopeptide bond between the C-terminal glycine of SUMO and a lysine-amino group in the target. Enzymes involved in the sumoylation process are well conserved in A. nidulans based on the analysis of A. nidulans genomic DNA sequence database. The sumO and ubcN genes of A. nidulans encoding homologs of SUMO and Ubc9, respectively, were cloned. Null mutants of sumO and ubcN were not lethal in A. nidulans. Mycelial growth rate was not much affected but conidiation hardly occurred in both null mutants. Furthermore, cleistothecium was never found in various growth conditions, but Hulle cells were still observed. The sumO transcript was expressed to the similar level during asexual and sexual differentiation. delta-sumO and delta-UbcN exhibited high sensitivities to 4-NQO, MMS, CPT, and HU compared to those for wild-type. In conclusion, sumoylation process is required for proper differentiation and DNA repair in A. nidulans. [Supported by KOSEF]

abstract No: 


Full conference title: 

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