Identification and characterization of a novel gene Aokap1 involved in growth and kojic acid synthesis in Aspergillus oryzae

Li, Yuzhen; Zhang, Huanxin; Chen, Ziming; Fan, Junxia; Chen, YangQuan; Zeng, Bin

doi:10.1007/s00203-021-02718-4

Cited by 9 publications

(6 citation statements)

References 30 publications

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“…Its expression is also regulated by the pathway-specific regulator KojR [ 14 ], the global regulator LaeA [ 15 ], and several other regulators such as NrtA, KpeA, Aokap1, etc. [ 16 – 18 ]. To ensure its expression in A. niger , the kojA gene was placed under the control of the promoter of glyceraldehyde-3-phosphate dehydrogenase (P gpdA ), a strong and constitutive endogenous promoter in A. niger [ 28 ], to create the expression cassette for kojA (Fig.…”

Section: Resultsmentioning

confidence: 99%

Effective production of kojic acid in engineered Aspergillus niger

Zhang

et al. 2023

Microb Cell Fact

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Background Kojic acid (KA) is a widely used compound in the cosmetic, medical, and food industries, and is typically produced by Aspergillus oryzae. To meet increasing market demand, it is important to optimize KA production through seeking alternatives that are more economic than current A. oryzae-based methods. Results In this study, we achieved the first successful heterologous production of KA in Aspergillus niger, an industrially important fungus that does not naturally produce KA, through the expression of the kojA gene from A. oryzae. Using the resulting KA-producing A. niger strain as a platform, we identified four genes (nrkA, nrkB, nrkC, and nrkD) that negatively regulate KA production. Knocking down nrkA or deleting any of the other three genes resulted in a significant increase in KA production in shaking flask cultivation. The highest KA titer (25.71 g/L) was achieved in a pH controlled batch bioreactor using the kojA overexpression strain with a deletion of nrkC, which showed a 26.7% improvement compared to the KA titer (20.29 g/L) that was achieved in shaking flask cultivation. Conclusion Our study demonstrates the potential of using A. niger as a platform for studying KA biosynthesis and regulation, and for the cost-effective production of KA in industrial strain development.

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Section: Resultsmentioning

confidence: 99%

Effective production of kojic acid in engineered Aspergillus niger

Zhang

et al. 2023

Microb Cell Fact

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“…In contrast, AO090012000623 (nrtA) [28], AO090003000489 (laeA) [29], AO090009000298 (AoKap1) [30], AO090120000102 (AoKap2) [31], AO090113000139 (Aokap4) [32], AO090009000515 (Aokap5) [33], AO090113000133 (Aokap6) [34], AO090005000940 (AoZip2) [35], AO090012000498 (AozfA) [36], AO090003001186 (KpeA) [27], AO090020000046 (lreA) [27], and AO090009000320 (creB) [27], which may be related to KA synthesis according to previous reports, were not included in the DEGs in this study. Particularly, Chen et al reported a decreased expression of Aokap6 owing to kojR deletion; however, the degree of change was relatively low [34].…”

Section: Discussionmentioning

confidence: 97%

The Identification of a Target Gene of the Transcription Factor KojR and Elucidation of Its Role in Carbon Metabolism for Kojic Acid Biosynthesis in Aspergillus oryzae

Mizutani,

Oka,

Goto

et al. 2024

JoF

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DNA-binding transcription factors are broadly characterized as proteins that bind to specific sequences within genomic DNA and modulate the expression of downstream genes. This study focused on KojR, a transcription factor involved in the metabolism of kojic acid, which is an organic acid synthesized in Aspergillus oryzae and is known for its tyrosinase-inhibitory properties. However, the regulatory mechanism underlying KojR-mediated kojic acid synthesis remains unclear. Hence, we aimed to obtain a comprehensive identification of KojR-associated genes using genomic systematic evolution of ligands by exponential enrichment with high-throughput DNA sequencing (gSELEX-Seq) and RNA-Seq. During the genome-wide exploration of KojR-binding sites via gSELEX-Seq and identification of KojR-dependent differentially expressed genes (DEGs) using RNA-Seq, we confirmed that KojR preferentially binds to 5′-CGGCTAATGCGG-3′, and KojR directly regulates kojT, as was previously reported. We also observed that kojA expression, which may be controlled by KojR, was significantly reduced in a ΔkojR strain. Notably, no binding of KojR to the kojA promoter region was detected. Furthermore, certain KojR-dependent DEGs identified in the present study were associated with enzymes implicated in the carbon metabolic pathway of A. oryzae. This strongly indicates that KojR plays a central role in carbon metabolism in A. oryzae.

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“…As the upstream of laeA , loss of function in the histone deacetylase gene AoHst4 contributes to kojic acid biosynthesis, coupled with high levels of expression of kojA , kojR and kojT [ 6 ]. Additionally, some membrane proteins have been reported to be involved in kojic acid production, such as NrtA, AoZip2, AoKap1 and AoKap2 [ 5 , 11 , 12 , 13 ]. In A. oryzae , nrtA encodes a nitrate transporter, which abolishes the suppressive effect of nitrate on kojic acid production [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…RNA interference of the ZIP transporter gene AoZip2 inhibits kojic acid biosynthesis [ 12 ]. Aokap1 and Aokap2 both encode an uncharacterized protein with transmembrane domains, and the knockout of Aokap1 or the overexpression of Aokap2 contributes to kojic acid production [ 11 , 13 ]. These proteins affect kojic acid production via altered expression of kojA , kojR and kojT [ 4 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…Aokap1 and Aokap2 both encode an uncharacterized protein with transmembrane domains, and the knockout of Aokap1 or the overexpression of Aokap2 contributes to kojic acid production [ 11 , 13 ]. These proteins affect kojic acid production via altered expression of kojA , kojR and kojT [ 4 , 11 , 12 , 13 ]. The kojic acid gene cluster of A. oryzae was identified a decade ago, and consists of three genes: kojA , kojR and kojT .…”

Section: Introductionmentioning

confidence: 99%

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A Novel Major Facilitator Superfamily Transporter Gene Aokap4 near the Kojic Acid Gene Cluster Is Involved in Growth and Kojic Acid Production in Aspergillus oryzae

Chen

et al. 2022

JoF

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Kojic acid is an important secondary metabolite of industrial importance produced by Aspergillus oryzae. The kojic acid gene cluster plays an essential role in kojic acid production, and harbors kojA, kojR and kojT. The deletion of kojT, encoding a major facilitator superfamily (MFS) transporter, did not completely abolish kojic acid production, implying that other transporters are required for the transport of kojic acid. The aim of this study is to look for the transporters involved in kojic acid production. Here, Aokap4 encoding a novel MFS transporter was identified, which was adjacent to kojT in the kojic acid gene cluster. The deletion of Aokap4 contributed to the hyphal growth, conidial production and biomass of A. oryzae. Moreover, Aokap4 is required for heat- and cell-wall-stress tolerance but not oxidative and osmotic stress. The disruption of Aokap4 impaired kojic acid production with the reduced expression of kojA, kojR and kojT. Furthermore, when kojT was deleted in the Aokap4-disrupted strain, the yield of kojic acid declined to the same level as that of the kojT-deletion mutant, whereas the production of kojic acid was recovered when kojT was overexpressed in the Aokap4 knockout strain, suggesting that kojT acts downstream of Aokap4. AoKap4 was the second identified MSF transporter involved in kojic acid production after kojT was found a decade ago. This study contributes to a better understanding of the biological roles of the MFS transporter and lays a foundation for future studies on kojic acid synthesis in A. oryzae.

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Identification and characterization of a novel gene Aokap1 involved in growth and kojic acid synthesis in Aspergillus oryzae

Cited by 9 publications

References 30 publications

Effective production of kojic acid in engineered Aspergillus niger

Effective production of kojic acid in engineered Aspergillus niger

The Identification of a Target Gene of the Transcription Factor KojR and Elucidation of Its Role in Carbon Metabolism for Kojic Acid Biosynthesis in Aspergillus oryzae

A Novel Major Facilitator Superfamily Transporter Gene Aokap4 near the Kojic Acid Gene Cluster Is Involved in Growth and Kojic Acid Production in Aspergillus oryzae

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