Phosphorylation-dependent control of an RNA granule-localized protein that finetunes defence gene expression at a post-transcriptional level.
Mitogen-activated protein kinase (MAPK) cascades are key signalling modules of plant defense responses to pathogen-associated molecular patterns (PAMPs, e.g. bacterial flg22 peptide). The Tandem Zinc Finger Protein 9 (TZF9) is an RNA-binding protein that is phosphorylated by two PAMP-responsive MAPKs, MPK3 and MPK6. A team of scientists from the IPB and MLU now mapped the major phosphosites in TZF9 and showed their importance in plant immunity.
By using Microarray analysis, the researchers showed the impact of TZF9 on the association of mRNA to the ribosomes and found that TZF9 may inhibit translation of a subset of mRNAs. Interestingly, TZF9 physically interacts with poly(A)-binding protein 2 (PAB2), a hallmark constituent of stress granules. These granules are a site for stress-induced translational arrest. Hence, MAPKs may control defense gene expression post-transcriptionally through release from translation arrest within TZF9-PAB2-containing RNA granules or perturbing PAB2 functions in translation control.
