A MYB MYB ‐type transcription factor, MYB MYB 2, represses light‐harvesting protein genes in Cyanidioschyzon merolae Cyanidioschyzon merolae

摘要

While searching for transcriptional regulators that respond to changes in light regimes, we identified a MYB domain‐containing protein, MYB 2, that accumulates under dark and other conditions in the unicellular red alga Cyanidioschyzon merolae . The isolation and analysis of a MYB 2 mutant revealed that MYB 2 represses the expression of the nuclear‐encoded chloroplast RNA polymerase sigma factor gene SIG 2 , which results in the repression of the chloroplast‐encoded phycobilisome genes that are under its control. Since nuclear‐encoded phycobilisome and other light‐harvesting protein genes are also repressed by MYB 2, we conclude that MYB 2 has a role in repressing the expression of light‐harvesting genes. The MYB 2 mutant is sensitive to a prolonged dark incubation, indicating the importance of MYB 2 for cell viability in the dark.