2Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33/2, 119071 Moscow, Russia; fax: (495) 954-2732
3Chemical Faculty, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-0997; E-mail: email@example.com
4Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142292 Pushchino, Moscow Region, Russia; fax: (495) 923-3602
* To whom correspondence should be addressed.
Received February 10, 2009; Revision received March 10, 2009
The gene encoding the xlnR xylanolytic activator of the heterologous fungus Aspergillus niger was incorporated into the Penicillium canescens genome. Integration of the xlnR gene resulted in the increase in a number of activities, i.e. endoxylanase, β-xylosidase, α-L-arabinofuranosidase, α-galactosidase, and feruloyl esterase, compared to the host P. canescens PCA 10 strain, while β-galactosidase, β-glucosidase, endoglucanase, and CMCase activities remained constant. Two different expression constructs were developed. The first consisted of the nucleotide sequence containing the mature P. canescens phytase gene under control of the axhA promoter region gene encoding A. niger (1,4)-β-D-arabinoxylan-arabinofuranohydrolase. The second construct combined the P. canescens phytase gene and the bgaS promoter region encoding homologous β-galactosidase. Both expression cassettes were transformed into P. canescens host strain containing xlnR. Phytase synthesis was observed only for strains with the bgaS promoter on arabinose-containing culture media. In conclusion, the bgaS and axhA promoters were regulated by different inducers and activators in the P. canescens strain containing a structural tandem of the axhA promoter and the gene of the xlnR xylanolytic activator.
KEY WORDS: xylanolytic activator, xlnR, Penicillium canescens axhA promoter, Aspergillus niger