Allosteric deactivation of PIFs and EIN3 by microproteins in light control of plant development

Significance How plants respond and adjust their growth to cope with environmental changes is a long-standing question in biology. By studying the initial dark-to-light transition, we reveal that a microprotein-imposed suppression of protein activity is adopted by plants to achieve rapid switch from skotomorphogenic to photomorphogenic programs. Microproteins are essential bioactive regulators in animals. A large number of microproteins are predicted in plants, but very few of them are functionally characterized. We identified two microproteins that are tissue-specifically stimulated by light and directly disrupt the oligomerization of key transcription factors in light signaling. This microprotein-directed allosteric deactivation can be utilized to develop versatile tools for posttranslational regulation of target proteins in molecular breeding.