Functional analysis of three putative galactofuranosyltransferases with redundant functions in galactofuranosylation in Aspergillus niger

Mark Arentshorst,Cees A M J J Van Den Hondel,Arthur F J Ram,Ebru Alazi,Davina De Lange,Ellen L Lagendijk,Joohae Park

doi:10.1007/s00203-019-01709-w

Mark Arentshorst, Cees A M J J Van Den Hondel + Show 5 more

Open Access

https://doi.org/10.1007/s00203-019-01709-w

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Journal: Archiv für Mikrobiologie	Publication Date: Aug 1, 2019
Citations: 12	License type: open-access

Affiliation: Leiden University, Koppert (Netherlands)

Abstract

Galactofuranose (Galf)-containing glycostructures are important to secure the integrity of the fungal cell wall. Golgi-localized Galf-transferases (Gfs) have been identified in Aspergillus nidulans and Aspergillus fumigatus. BLASTp searches identified three putative Galf-transferases in Aspergillus niger. Phylogenetic analysis showed that they group in three distinct groups. Characterization of the three Galf-transferases in A. niger by constructing single, double, and triple mutants revealed that gfsA is most important for Galf biosynthesis. The growth phenotypes of the ΔgfsA mutant are less severe than that of the ΔgfsAC mutant, indicating that GfsA and GfsC have redundant functions. Deletion of gfsB did not result in any growth defect and combining ΔgfsB with other deletion mutants did not exacerbate the growth phenotype. RT-qPCR experiments showed that induction of the agsA gene was higher in the ΔgfsAC and ΔgfsABC compared to the single mutants, indicating a severe cell wall stress response after multiple gfs gene deletions.

Highlights

Galactofuranose (Galf) is an important constituent of the fungal cell wall (Tefsen et al 2012; Oka and Goto 2016)
Several studies in A. fumigatus and A. nidulans have shown that similar gene sets of UDP-glucose 4-epimerases, UDP-galactomutases, and UDP-Galf-transporters are present in these fungi and are important for Galf biosynthesis
Galf-transferases in the genome of A. niger were identified by BlastP searches using the A. nidulans and A. fumigatus GfsA proteins as queries

Summary

Introduction

Galactofuranose (Galf) is an important constituent of the fungal cell wall (Tefsen et al 2012; Oka and Goto 2016). Galf is the five-membered ring form of galactose and is found in several cell surface fractions. It has been identified as a component of the cell wall galactomannan fraction in Aspergilli, as a part of N- and O-glycans of extracellular proteins, and within glycosphingolipids (Bardalaye and Nordin 1977; Baretto-Bergter et al 1980; Wallis et al 1999; Toledo et al 2007). Several studies in A. fumigatus and A. nidulans have shown that similar gene sets of UDP-glucose 4-epimerases, UDP-galactomutases, and UDP-Galf-transporters are present in these fungi and are important for Galf biosynthesis Several studies in A. fumigatus and A. nidulans have shown that similar gene sets of UDP-glucose 4-epimerases, UDP-galactomutases, and UDP-Galf-transporters are present in these fungi and are important for Galf biosynthesis (Lee et al 2014; El-Ganiny et al 2008, 2010; Schmalhorst et al 2008; Engel et al. Vol.:(0123456789)

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