Sulfenylation of ENOLASE2 facilitates HO-conferred freezing tolerance in Arabidopsis.

HO affects the expression of genes that are involved in plant responses to diverse environmental stresses; however, the underlying mechanisms remain elusive. Here, we demonstrate that HO enhances plant freezing tolerance through its effect on a protein product of low expression of osmotically responsive genes2 (LOS2). LOS2 is translated into a major product, cytosolic enolase2 (ENO2), and sometimes an alternative product, the transcription repressor c-Myc-binding protein (MBP-1). ENO2, but not MBP-1, promotes cold tolerance by binding the promoter of C-repeat/DRE binding factor1 (CBF1), a central transcription factor in plant cold signaling, thus activating its expression. Overexpression of CBF1 restores freezing sensitivity of a LOS2 loss-of-function mutant. Furthermore, cold-induced HO increases nuclear import and transcriptional binding activity of ENO2 by sulfenylating cysteine 408 and thereby promotes its oligomerization. Collectively, our results illustrate how HO activates plant cold responses by sulfenylating ENO2 and promoting its oligomerization, leading to enhanced nuclear translocation and transcriptional activation of CBF1.