Effects on Gene Transcription Profile and Fatty Acid Composition by Genetic Modification of Mevalonate Diphosphate Decarboxylase MVD/Erg19 in Aspergillus Oryzae.

Hu Hu,Huang Huang,Jiang Jiang,Zeng Zeng,Sun Sun,Li Li,Niu Niu,Xu Xu,Zhang Zhang,Liu Liu

doi:10.3390/microorganisms7090342

Abstract

Mevalonate diphosphate decarboxylase MVD/Erg19 is required for ergosterol biosynthesis, growth, sporulation, and stress tolerance in Aspergillus oryzae. In this study, RNA-seq was used to analyze the gene transcription profile in AoErg19 overexpression (OE) and RNAi strains. There were 256 and 74 differentially expressed genes (DEGs) in AoErg19 OE and RNAi strains, respectively, compared with the control strain (CK). The most common DEGs were transport- and metabolism-related genes. Only 22 DEGs were obtained that were regulated in both OE and RNAi strains. The transcriptomic comparison between CK and AoErg19 overexpression strain (CK vs. OE), and between CK and AoErg19 RNAi strain (CK vs. RNAi) revealed that the greatest difference existed in the number of genes belonging to the cytochrome P450 family; 12 were found in CK vs. OE, whereas 1 was found in CK vs. RNAi. The expression patterns of lipid biosynthesis and metabolism related genes were altered in OE and RNAi strains, either by gene induction or suppression. Moreover, the total fatty acid content in the RNAi strain was 12.1% greater than the control strain, but no difference in total acid content was found between the overexpression strain and the control strain. Therefore, this study highlights the gene expression regulation within mevalonate (MVA), ergosterol biosynthesis, and fatty acid biosynthesis pathways.

Highlights

The mevalonate (MVA) pathway is conserved among organisms [1]
Mevalonate diphosphate decarboxylase (MVD; EC 4.1.1.33) catalyzes the decarboxylation of six-carbon mevalonate 5-diphosphate (MVA-PP) to five-carbon isopentenyl diphosphate (IPP) [8], which the basic structure required for the biosynthesis of isoprenoids, and acts as an important cellular intermediate [9]
This study aims to identify details on gene expression regulation within the MVA, ergosterol biosynthesis, and fatty acid biosynthesis pathways, which may lay the foundation for the genetic engineering of lipid biosynthesis and other metabolic pathways in this industrially important fungus

Summary

Introduction

The mevalonate (MVA) pathway is conserved among organisms [1]. This pathway produces isoprenoids, the most numerous and structurally diverse family of natural compounds [2]. The MVA pathway is initiated by the condensation of two acetyl-CoA molecules, which is catalyzed by acetoacetyl-CoA thiolase (EC 2.3.1.9), forming acetoacetyl-CoA [6]. A third acetyl-CoA reacts with acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) via hydroxymethylglutaryl-CoA synthase (EC 2.3.3.10) [4]. 2.7.1.36) and phosphomevalonate kinase (EC 2.7.4.2) successively, producing mevalonate 5-diphosphate (MVA-PP). Mevalonate diphosphate decarboxylase (MVD; EC 4.1.1.33) catalyzes the decarboxylation of six-carbon MVA-PP to five-carbon isopentenyl diphosphate (IPP) [8], which the basic structure required for the biosynthesis of isoprenoids, and acts as an important cellular intermediate [9]

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Conclusion