Characterization of a cytochrome P450 monooxygenase gene involved in the biosynthesis of geosmin in Penicillium expansum

Muhammad Hussnain Siddique, Thierry Liboz, Nafees Bacha, Olivier Puel, Florence Mathieu and Ahmed Lebrihi

Résumé:

Geosmin  is  a  terpenoid,  an  earthy-smelling  substance  associated  with  off-flavors  in  water  and  wine. The biosynthesis of geosmin is well characterized in bacteria, but little is known about its production in eukaryotes, especially in filamentous fungi. The origin of geosmin in grapevine is largely attributable to the presence of Penicillium expansum on grapes. Herein, we describe the characterization of “gpe1”, a gene encoding a cytochrome P450 monooxygenase probably involved in the biosynthesis of geosmin in this species. A gpe1 knockout mutant of P. expansum M2230 lost the capacity to produce geosmin, while  the  genetically  complemented  mutant  restored  it.  The  deduced gpe1 protein  sequence  shows identities  with  other  cytochrome  P450  monooxygenases  involved  in  diterpene  biosynthesis.  These enzymes  catalyze  the  addition  of  hydroxyl  groups  to  the  diterpene  compounds. gpe1 protein  could work  in  the  same  way,  with  sesquiterpenes  as  substrates.  This  gene  seems  to  be  only  present  in geosmin-producing Penicillium species. To our knowledge, this is the first characterization of a fungal gene encoding an enzyme involved in geosmin biosynthesis

Revue:

African Journal of Microbiology Research

Lien:

www.academicjournals.org/article/article1380706906_Siddique%20et%20al.pdf