A novel, inducible, citral lyase purified from spores of Penicillium digitatum

Abstract

A novel lyase, combining hydratase and aldolase activity, that converts citral into methylheptenone and acetaldehyde, was purified from spores of Penicillium digitatum. Remarkably, citral lyase activity was induced 118-fold by incubating nongerminating spores with the substrate, citral. This cofactor independent hydratase/aldolase, was purified and found to be a monomeric enzyme of 31 kDa. Citral lyase has a K m of 0.058 mM and a V max of 52.6 UAEmg )1. Enzyme activity was optimal at 20°C and pH 7.6. The enzyme has a strong preference for the trans isomer of citral (geranial). Citral lyase also converts other a,b-unsaturated aldehydes (farnesal, methyl-crotonaldehyde, decenal and cinnemaldehyde).

Alternative Management Approaches of Citrus Diseases Caused by Penicillium digitatum (Green Mold) and Penicillium italicum (Blue Mold)

“…In other research, supplementing carnauba wax with Cinnamomum zeylanicum essential oil (0.5%, v/v) achieved 90% disease control against post-harvest P. digitatum and P. italicum in citrus (Kouassi et al, 2012 ). In addition, citral, a naturally occurring isoprenoid compound with two isomers (geranial and neral), provided antifungal activity against P. digitatum in “Navel” oranges (Wolken et al, 2002 ; Wuryatmo et al, 2003 ; Droby et al, 2008 ). Fan et al ( 2014 ) found that citral combined with wax in vitro and in vivo decreased the incidence of P. digitatum in “Ponkan” mandarins with significant increases in Vc content and antioxidant enzymes (catalase, SOD, and peroxidase).…”

Synthesis of the aggregation pheromone of the Colorado potato beetle from its degradation product

“…18,19 In this degradation pathway oxidation of the alcohols (geraniol, nerol) to aldehydes was followed by their decomposition, which was attributed to a specific enzyme named citral lyase. 19,20 Biotransformation of farnesol by several fungal species (Fusarium culmorum, B. cinerea, Rhodotorula rubra, Rhodotorula marina) produced an analogous ketone-6,10-dimethyl-5,9-undecadien-2-one (geranylacetone). 21 It seems therefore that such ketones are common degradation products of terpenes in microorganisms.…”

“…In the decomposition of citral involvement of a specific lyase has been proposed. 19,20 However, comparison of the pheromone structure to the wide-spread microbial metabolite acetoin suggested a simpler mechanism. Acetoin, which contains neighboring ketone and secondary alcohol groups, is degraded to acetaldehyde and acetyl-CoA by acetoin dehydrogenase belonging to the b-ketoacid dehydrogenase family, which utilizes thiamine pyrophosphate as a cofactor.…”