Role of Ace2 (Activator of Cellulases 2) within the xyn2 transcriptosome of Hypocrea jecorina

Ace2 (Activator of Cellulases 2)-encoding gene was deleted from and retransformed in the H. Jecorina QM9414 genome. Comparison of xylanase activity and xyn2 transcription of the corresponding strains after cultivation on inducing compounds (xylan, xylobiose) revealed a faster initial inducibility in the Delta ace2-strain, but final levels of xyn2 transcript and xylanase activity of the parental strain could not be reached. This suggests a role for Ace2 in the regulation of xyn2 induction mechanisms, moreover Ace2 is responsible for the basal level of xyn2 transcription. Furthermore, a palindrome in the xyn2 promoter consisting of a GGGTAA- and a CCAGCC-element was identified. Both Xyr1 and Ace2 are able to bind the complete motif, the latter also only to one part of it. Phosphorylation as well as dimerization are prerequisites for binding of Ace2 to the xyn2 promoter. Finally, the impact of Ace2 on xyl-1 transcription could be demonstrated under inducing conditions. (C) 2007 Elsevier Inc. All rights reserved.