The Arabidopsis Phytochrome-Interacting Factor PIF7, Together with PIF3 and PIF4, Regulates Responses to Prolonged Red Light by Modulating phyB Levels Export

@article{citeulike:3379971, abstract = {We show that a previously uncharacterized Arabidopsis thaliana basic helix-loop-helix (bHLH) phytochrome interacting factor (PIF), designated PIF7, interacts specifically with the far-red light-absorbing Pfr form of phyB through a conserved domain called the active phyB binding motif. Similar to PIF3, upon light exposure, PIF7 rapidly migrates to intranuclear speckles, where it colocalizes with phyB. However, in striking contrast to PIF3, this process is not accompanied by detectable light-induced phosphorylation or degradation of PIF7, suggesting that the consequences of interaction with photoactivated phyB may differ among PIFs. Nevertheless, PIF7 acts similarly to PIF3 in prolonged red light as a weak negative regulator of phyB-mediated seedling deetiolation. Examination of pif3, pif4, and pif7 double mutant combinations shows that their moderate hypersensitivity to extended red light is additive. We provide evidence that the mechanism by which these PIFs operate on the phyB signaling pathway under prolonged red light is through maintaining low phyB protein levels, in an additive or synergistic manner, via a process likely involving the proteasome pathway. These data suggest that the role of these phyB-interacting bHLH factors in modulating seedling deetiolation in prolonged red light may not be as phy-activated signaling intermediates, as proposed previously, but as direct modulators of the abundance of the photoreceptor. 10.1105/tpc.107.052142}, author = {Leivar, Pablo and Monte, Elena and Al-Sady, Bassem and Carle, Christine and Storer, Alyssa and Alonso, Jose M. and Ecker, Joseph R. and Quail, Peter H.}, citeulike-article-id = {3379971}, citeulike-linkout-0 = {http://dx.doi.org/10.1105/tpc.107.052142}, citeulike-linkout-1 = {http://www.plantcell.org/cgi/content/abstract/20/2/337}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/18252845}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=18252845}, day = {1}, doi = {10.1105/tpc.107.052142}, journal = {Plant Cell}, keywords = {phyb, pif, red}, month = {February}, number = {2}, pages = {337--352}, posted-at = {2009-03-26 14:23:21}, priority = {2}, title = {The Arabidopsis Phytochrome-Interacting Factor PIF7, Together with PIF3 and PIF4, Regulates Responses to Prolonged Red Light by Modulating phyB Levels}, url = {http://dx.doi.org/10.1105/tpc.107.052142}, volume = {20}, year = {2008} }

TY - JOUR ID - citeulike:3379971 L3 - citeulike-article-id:3379971 N2 - We show that a previously uncharacterized Arabidopsis thaliana basic helix-loop-helix (bHLH) phytochrome interacting factor (PIF), designated PIF7, interacts specifically with the far-red light-absorbing Pfr form of phyB through a conserved domain called the active phyB binding motif. Similar to PIF3, upon light exposure, PIF7 rapidly migrates to intranuclear speckles, where it colocalizes with phyB. However, in striking contrast to PIF3, this process is not accompanied by detectable light-induced phosphorylation or degradation of PIF7, suggesting that the consequences of interaction with photoactivated phyB may differ among PIFs. Nevertheless, PIF7 acts similarly to PIF3 in prolonged red light as a weak negative regulator of phyB-mediated seedling deetiolation. Examination of pif3, pif4, and pif7 double mutant combinations shows that their moderate hypersensitivity to extended red light is additive. We provide evidence that the mechanism by which these PIFs operate on the phyB signaling pathway under prolonged red light is through maintaining low phyB protein levels, in an additive or synergistic manner, via a process likely involving the proteasome pathway. These data suggest that the role of these phyB-interacting bHLH factors in modulating seedling deetiolation in prolonged red light may not be as phy-activated signaling intermediates, as proposed previously, but as direct modulators of the abundance of the photoreceptor. 10.1105/tpc.107.052142 IS - 2 JF - Plant Cell EP - 352 TI - The Arabidopsis Phytochrome-Interacting Factor PIF7, Together with PIF3 and PIF4, Regulates Responses to Prolonged Red Light by Modulating phyB Levels VL - 20 SP - 337 KW - phyb KW - pif KW - red AU - Leivar, Pablo AU - Monte, Elena AU - Al-Sady, Bassem AU - Carle, Christine AU - Storer, Alyssa AU - Alonso, Jose AU - Ecker, Joseph AU - Quail, Peter PY - 2008/02/01/ UR - http://dx.doi.org/10.1105/tpc.107.052142 ER -