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

• Published in: Journal of fungi (Basel) Vol. 10; no. 2
• Main Authors: Mizutani, Tomoka, Oka, Hiroya, Goto, Riko, Tsurigami, Ryoga, Maruyama, Jun-ichi, Shimizu, Motoyuki, Kato, Masashi, Nakano, Hideo, Kojima, Takaaki
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.01.2024
• Subjects: Biosynthesis; DNA binding proteins; DNA sequencing; Ethylenediaminetetraacetic acid; Genetic aspects; Genomics; Nucleotide sequencing; Protein binding; RNA; RNA sequencing; Scientific equipment and supplies industry; United States; Japan
• ISSN: 2309-608X; 2309-608X
• DOI: 10.3390/jof10020113

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.