The CRZ-1 transcription factor binds to specific sequences in the promoters of al-2, cao-2, and ylo-1 to regulate the expression of these carotenoid biosynthesis genes in Neurospora crassa

The calcineurin-CRZ-1 signaling pathway regulates the carotenoid biosynthesis pathway in Neurospora crassa. The expression of different carotenoid biosynthesis genes al-1, al-2, al-3, cao-2, and ylo-1 was downregulated in the Cna-1^RIP mutants. Additionally, the repression of cna-1, cnb-1, and crz-1 causes a reduction in overall carotenoid accumulation and a compromised expression in the carotenoid biosynthesis genes. We predicted and determined the exact CRZ-1 binding sites in the carotenoid biosynthesis genes al-2, cao-2, and ylo-1 genes. CRZ-1 binds in the promoter of al-2 in three different regions − 948 to − 955 bp, − 1268 to − 1275 bp, and − 897 to − 904 bp. Similarly, CRZ-1 binds to two different regions − 1742 to − 1749 and − 1232 to − 1239 bp in cao-2, and three different regions − 557 to − 564, − 513 to − 520, and − 511 to − 518 bp in the upstream of the start codon of ylo-1. Therefore, the CRZ-1 transcription factor regulates carotenoid biosynthesis genes in N. crassa.