Mevalonate Diphosphate Decarboxylase MVD/Erg19 Is Required for Ergosterol Biosynthesis, Growth, Sporulation and Stress Tolerance in Aspergillus oryzae.

Yunlong Sun,Zhihong Hu,Yayi Tu,Van-Tuan Tran,Long Ma,Bin Zeng,Yali Niu,Hui Huang,Bin He

doi:10.3389/fmicb.2019.01074

Abstract

Mevalonate diphosphate decarboxylase (MVD; EC 4.1.1.33) is a key enzyme of the mevalonic acid (MVA) pathway. In fungi, the MVA pathway functions as upstream of ergosterol biosynthesis, and MVD is also known as Erg19. Previously, we have identified Aoerg19 in Aspergillus oryzae using bioinformatic analysis. In this study, we showed that AoErg19 function is conserved using phylogenetic analysis and yeast complementation assay. Quantitative reverse transcription–PCR (qRT-PCR) indicated that Aoerg19 expression changed in different growth stages and under different forms of abiotic stress. Subcellular localization analysis showed that AoErg19 was located in the vacuole. Overexpression of Aoerg19 decreased the ergosterol content in A. oryzae, which may due to the feedback-mediated downregulation of Aoerg8. Consistent with the decrease in ergosterol content, both Aoerg19 overexpression and RNAi strains of A. oryzae are sensitive to abiotic stressors, including ergosterol biosynthesis inhibitor, temperature, salt and ethanol. Thus, we have identified the function of AoErg19 in A. oryzae, which may assist in genetic modification of MVA and the ergosterol biosynthesis pathway.

Highlights

Mevalonate diphosphate decarboxylase (MVD; EC 4.1.1.33) is a key enzyme of the mevalonic acid (MVA) pathway (Krepkiy and Miziorko, 2004). It catalyzes the decarboxylation of the six-carbon mevalonate 5-diphosphate (MVAPP) to the five-carbon isopentenyl diphosphate (IPP) (Krepkiy and Miziorko, 2004), the basic structure required for the biosynthesis of isoprenoids, an important cellular intermediate (Bergès et al, 1997)
IPP is the precursor required for ergosterol biosynthesis and MVD is a crucial enzyme required for cell viability because the Identification MVD/Erg19 in Aspergillus oryzae mutant of the corresponding gene was lethal at 35◦C (Bergès et al, 1997)
MVD in the filamentous fungus A. oryzae is known as erg19 homolog in the yeast S. cerevisiae; we named the homologous gene in A. oryzae as Aoerg19

Summary

Introduction

Mevalonate diphosphate decarboxylase (MVD; EC 4.1.1.33) is a key enzyme of the mevalonic acid (MVA) pathway (Krepkiy and Miziorko, 2004). It catalyzes the decarboxylation of the six-carbon mevalonate 5-diphosphate (MVAPP) to the five-carbon isopentenyl diphosphate (IPP) (Krepkiy and Miziorko, 2004), the basic structure required for the biosynthesis of isoprenoids, an important cellular intermediate (Bergès et al, 1997). The reduced activity of MVD has been associated with lower serum cholesterol levels and subsequently severe hypertension and cerebral hemorrhage (Michihara et al, 1998)

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