Genome-wide identification of the fatty acid desaturases gene family in four Aspergillus species and their expression profile in Aspergillus oryzae

Wen Tang,Qinqin Wu,Bin He,Lijun Fu,Changsheng Ouyang,Jie Wang,Lanlan Liu,Chuanhui Zeng,Bin Zeng,Haoran Li

doi:10.1186/s13568-018-0697-x

Abstract

Fatty acid desaturases play a key role in producing polyunsaturated fatty acids by converting single bonds to double bonds. In the present study, a total of 13, 12, 8 and 8 candidate fatty acid desaturases genes were identified in the Aspergillus oryzae, Aspergillus flavus, Aspergillus fumigatus and Aspergillus nidulans genomes through database searches, which were classified into five different subfamilies based on phylogenetic analysis. Furthermore, a comprehensive analysis was performed to characterize conserved motifs and gene structures, which could provide an intuitive comprehension to learn the relationship between structure and functions of the fatty acid desaturases genes in different Aspergillus species. In addition, the expression pattern of 13 fatty acid desaturases genes of A. oryzae was tested in different growth stages and under salt stress treatment. The results revealed that the fatty acid desaturases genes in A. oryzae were highly expressed in adaptive phase growth and up-regulated under salt stress treatment. This study provided a better understanding of the evolution and functions of the fatty acid desaturases gene family in the four Aspergillus species, and would be useful for seeking methods to improve the production of unsaturated fatty acids and enhance efforts for the genetic improvement of strains to adapt to the complex surrounding environment.

Highlights

Unsaturated fatty acids, which contain one or more double bonds, are the major structural components of cell membranes
Identification of fatty acid desaturases genes in the six species The candidate fatty acid desaturases genes were identified from the A. oryzae, A. flavus, A. fumigatus and A. nidulans genome using the Blast programs with the query sequences of S. cerevisiae and M. farinosa fatty acid desaturases genes
A total of 13, 12, 8 and 8 candidate fatty acid desaturases genes were identified in the A. oryzae, A. flavus, A. fumigatus and A. nidulans genomes, respectively (Table 1)

Summary

Introduction

Unsaturated fatty acids, which contain one or more double bonds, are the major structural components of cell membranes. They play significant roles in maintaining cell structure and the membrane fluidity, which are involved in development, energy metabolism and stress response (Pereira et al 2003). The soluble fatty acid desaturases, such as the plant Acyl-carrier-protein (ACP) desaturase family, use acyl carrier protein thioesters as substrates, and use ferredoxin oxidoreductase and ferredoxin as electron donors. The membrane-bound fatty acid desaturases, which include Δ5-, Δ6-, Δ9-, Δ12- and Δ15-desaturase in the mammals, fungi, insects, higher plants and cyanobacteria, use fatty acids esterified to complex lipid as the substrate, and use cytochrome (cyt) b5 oxidoreductase and cyt b5 as electron donors. Most of fatty acid desaturases share three highly conserved histidine boxes: ʻHXXXXH, ʻHXXHHandQXXHHincluded in

Methods

Results

Conclusion