title: The amyR-deletion strain of Aspergillus niger CICC2462 is a suitable host strain to express secreted protein with a low background.
abstract: BACKGROUND
  The filamentous fungus Aspergillus niger is widely exploited as an important expression host for industrial production. The glucoamylase high-producing strain A. niger CICC2462 has been used as a host strain for the establishment of a secretion expression system. It expresses recombinant xylanase, mannase and asparaginase at a high level, but some high secretory background proteins in these recombinant strains still remain, such as alpha-amylase and alpha-glucosidase; lead to a low-purity of fermentation products. The aim was to construct an A. niger host strain with a low background of protein secretion.
  
  
  RESULTS
  The transcription factor amyR was deleted in A. niger CICC2462, and the results from enzyme activity assays and SDS-PAGE analysis showed that the glucoamylase and amylase activities of the ∆amyR strains were significantly lower than those of the wild-type strain. High-throughput RNA-sequencing and shotgun LC-MS/MS proteomic technology analysis demonstrated that the expression of amylolytic enzymes was decreased at both the transcriptional and translational levels in the ∆amyR strain. Interestingly, the ∆amyR strain growth rate better than the wild-type strain.
  
  
  CONCLUSIONS
  Our findings clearly indicated that the ∆amyR strain of A. niger CICC2462 can be used as a host strain with a low background of protein secretion.
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China.
authors.forename: Xiang Xiang
authors.initials: XX
authors.lastname: Zhang
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
authors.forename: Fuping
authors.initials: F
authors.lastname: Song
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China. 1065237667@qq.com.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Northeast Agricultural University College of Life Science, Harbin, 150030, China. 763725521@qq.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism; D007218:Industrial Microbiology / Q000379:methods; D030781:Organisms, Genetically Modified; D040901:Proteomics; D055571:Secretory Pathway / Q000235:genetics; D053719:Tandem Mass Spectrometry; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; D015534:Trans-Activators; C414005:amyR protein, Aspergillus; D005087:Glucan 1,4-alpha-Glucosidase
keywords: Aspergillus niger; Proteomics; Regulation; Transcriptome; amyR