Towards Understanding Extracellular ROS Sensory and Signaling Systems in Plants
Figure 2
The protein domain structure of RCD1 and a hypothetical model of its action in the regulation of gene expression. (a) The RCD1 protein contains nuclear localization sequences (NLS), a N-terminal WWE-domain, and a PARP (poly(ADP) ribose polymerase) domain, however, without PARP activity [34], and a C-terminal protein-protein interaction domain RST which mediates specific interaction with several transcription factors [35]. (b) Poly(ADP)ribosylation is mediated by the activity of PARP (poly(ADP)ribose polymerase), which transfers ADP-ribose from NAD+ to a target protein forming poly(ADP) ribose (PAR). PAR can be removed by PARG (PAR glycohydrolase). RCD1 is assumed to bind PARsylated proteins. (c) Hypothetical model for RCD1 as a positive regulator of specific transcription: RCD1 interacts through the RST-domain with specific transcription factors, binds PARsylated nuclear protein, and transports the interacting transcription factors to a target gene, where they bind to chromatin. The general transcription factor complex TFIID interacts with the specific transcription factor through the RST domain in TAF4, allows the binding of RNA polymerase, and initiates transcription. (d) Hypothetical model for RCD1 as a negative regulator of transcription: the general transcription factor complex TFIID interacts with the specific transcription factor through the RST domain in TAF4 and allows the binding of RNA polymerase to initiate transcription. PARP synthesizes PAR to a chromatin protein allowing RCD1 to interact with chromatin and compete through the RST domain for interaction of a specific transcription factor with TAF4 in the TFIID complex.
