TY - JOUR
T1 - l-Arabinose induces d-galactose catabolism via the Leloir pathway in Aspergillus nidulans
AU - Németh, Zoltán
AU - Kulcsár, László
AU - Flipphi, Michel
AU - Orosz, Anita
AU - Aguilar-Pontes, Maria Victoria
AU - de Vries, Ronald P
AU - Karaffa, Levente
AU - Fekete, Erzsébet
N1 - Copyright © 2018 Elsevier Inc. All rights reserved.
PY - 2019/2
Y1 - 2019/2
N2 - l-Arabinose and d-galactose are the principal constituents of l-arabinogalactan, and also co-occur in other hemicelluloses and pectins. In this work we hypothesized that similar to the induction of relevant glycoside hydrolases by monomers liberated from these plant heteropolymers, their respective catabolisms in saprophytic and phytopathogenic fungi may respond to the presence of the other sugar to promote synergistic use of the complex growth substrate. We showed that these two sugars are indeed consumed simultaneously by Aspergillus nidulans, while l-arabinose is utilised faster in the presence than in the absence of d-galactose. Furthermore, the first two genes of the Leloir pathway for d-galactose catabolism - encoding d-galactose 1-epimerase and galactokinase - are induced more rapidly by l-arabinose than by d-galactose eventhough deletion mutants thereof grow as well as a wild type strain on the pentose. d-Galactose 1-epimerase is hyperinduced by l-arabinose, d-xylose and l-arabitol but not by xylitol. The results suggest that in A. nidulans, l-arabinose and d-xylose - both requiring NADPH for their catabolisation - actively promote the enzyme infrastructure necessary to convert β-d-galactopyranose via the Leloir pathway with its α-anomer specific enzymes, into β-d-glucose-6-phosphate (the starting substrate of the oxidative part of the pentose phosphate pathway) even in the absence of d-galactose.
AB - l-Arabinose and d-galactose are the principal constituents of l-arabinogalactan, and also co-occur in other hemicelluloses and pectins. In this work we hypothesized that similar to the induction of relevant glycoside hydrolases by monomers liberated from these plant heteropolymers, their respective catabolisms in saprophytic and phytopathogenic fungi may respond to the presence of the other sugar to promote synergistic use of the complex growth substrate. We showed that these two sugars are indeed consumed simultaneously by Aspergillus nidulans, while l-arabinose is utilised faster in the presence than in the absence of d-galactose. Furthermore, the first two genes of the Leloir pathway for d-galactose catabolism - encoding d-galactose 1-epimerase and galactokinase - are induced more rapidly by l-arabinose than by d-galactose eventhough deletion mutants thereof grow as well as a wild type strain on the pentose. d-Galactose 1-epimerase is hyperinduced by l-arabinose, d-xylose and l-arabitol but not by xylitol. The results suggest that in A. nidulans, l-arabinose and d-xylose - both requiring NADPH for their catabolisation - actively promote the enzyme infrastructure necessary to convert β-d-galactopyranose via the Leloir pathway with its α-anomer specific enzymes, into β-d-glucose-6-phosphate (the starting substrate of the oxidative part of the pentose phosphate pathway) even in the absence of d-galactose.
U2 - 10.1016/j.fgb.2018.11.004
DO - 10.1016/j.fgb.2018.11.004
M3 - Article
C2 - 30496805
SN - 1087-1845
VL - 123
SP - 53
EP - 59
JO - Fungal Genetics and Biology
JF - Fungal Genetics and Biology
ER -