Figure 9.

A proposed model for the regulatory network involving in redox regulation of NOR by Msr during tomato fruit ripening. During tomato fruit ripening, reactive oxygen species accumulate in large quantities, which lead to protein oxidation, including Met oxidation in NOR (i.e. sulfoxidation). NOR sulfoxidation decreases the binding capacities of NOR with the promoters of ripening-related genes and the transcriptional activities, thereby inhibiting tomato fruit ripening. The oxidized NOR is reduced by E4 and SlMsrB2 to restore its DNA binding capacity and transcriptional activity. Simultaneously, the expression levels of E4 and SlMsrB2 also are regulated by NOR. Therefore, Msr-mediated dynamic modification of NOR redox status is involved in the regulation of tomato fruit ripening.