Post-translational protein modification as a tool for transcription reprogramming.

Precise modulation of transcription plays a vital role in both development and the response of all higher organisms to their environment. Temporal activation or repression of specific genes is accomplished via a plethora of transcriptional regulators. However, relatively little is known about how the activities of these proteins are controlled. Recent findings indicate that post-translational modifications fine-tune the function of transcription regulators by affecting their localization, conformation or stability. Here, we discuss these regulatory mechanisms in the context of the plant immune response. This system lends itself particularly well to studies of transcriptional regulators as activation of plant immunity is associated with rapid and dramatic reprogramming of the transcriptome. A case study of the plant immune coactivator NPR1 (nonexpressor of pathogenesis-related (PR) genes 1) illustrates that transcription regulator activity may be controlled by redox-based modifications of cysteine thiols (e.g. disulphide bonding and S-nitrosylation), phosphorylation, and ubiquitinylation coupled to protein degradation. Importantly, cross-talk between distinct protein modifications may determine the spatial and temporal activity of transcription regulators that in turn profile the cellular transcriptome.