High impact information on PID

• Constitutive expression of PID causes a phenotype in both shoots and roots that is similar to that of auxin-insensitive plants, implying that PID, which encodes a serine-threonine protein kinase, negatively regulates auxin signaling [1].
• Regulation of auxin response by the protein kinase PINOID [1].
• Arabidopsis plants carrying mutations in the PINOID (PID) gene have a pleiotropic shoot phenotype that mimics that of plants grown on auxin transport inhibitors or of plants mutant for the auxin efflux carrier PINFORMED (PIN), with defects in the formation of cotyledons, flowers, and floral organs [1].
• Overexpression of PID (PIDox) or the auxin efflux carrier component PINFORMED3 (PIN3, PIN3ox), specifically in the root hair cell, greatly suppressed root hair growth [2].
• Localization of PID or PIN3 at the cell boundary was disrupted by brefeldin A and staurosporine [2].

Biological context of PID

• PIN-FORMED1 and PINOID regulate boundary formation and cotyledon development in Arabidopsis embryogenesis [3].
• The gene ENHANCER OF PINOID controls cotyledon development in the Arabidopsis embryo [4].
• Cell extracts from flowers and seedling shoots dramatically increase PID phosphorylation in a tissue-specific manner [5].
• Phylogenetic analysis showed that the rice genome contains a single PID ortholog, OsPID [6].

Anatomical context of PID

• Here, using the auxin-sensitive Arabidopsis thaliana root hair cell system and the tobacco (Nicotiana tabacum) suspension cell system, we demonstrate that the protein kinase PINOID (PID) positively regulates auxin efflux [2].
• We find that PID specifically but non-selectively binds to phosphoinositides and phosphatidic acid, suggesting that PID might directly interact with the plasma membrane through protein-lipid interactions [7].
• PID immunoprecipitated from Arabidopsis cells in which PDK1 expression was inhibited by RNAi showed a dramatic reduction in transphosphorylation of myelin basic protein substrate [5].
• No ABR* kinase activity was detected in mesophyll cell protoplasts [8].

Associations of PID with chemical compounds

• Collectively, these results suggest that PID positively regulates cellular auxin efflux, most likely by modulating the trafficking of PIN and/or some other molecular partners involved in auxin efflux [2].
• The PINOID gene was recently cloned and found to encode a protein-serine/threonine kinase [9].
• We show that a PID activation loop serine is required for PDK1-dependent PID phosphorylation [5].
• The activation of ABR* kinase was dependent on the time and concentration of ABA [8].
• Characterization of OsPID, the Rice Ortholog of PINOID, and its Possible Involvement in the Control of Polar Auxin Transport [6].
• Our data suggest that PID plays a limited role in root development; loss of PID activity alters auxin transport and gravitropism without causing an obvious change in cellular polarity [10].

Other interactions of PID

• We also show that PID mRNA is localized mainly to the boundaries of cotyledon primordia and early expression of PID mRNA is dependent on PIN1 [3].
• A subset of GFP-tagged AGCVIIIa kinases expressed in Saccharomyces cerevisiae and tobacco BY-2 cells were preferentially localized to the cytoplasm (AGC1-7), nucleus (WAG1 and KIPK), and the cell periphery (PID) [7].
• Chemical inhibition of polar auxin transport (PAT) severely affects the apical-basal patterning of the gynoecium, as do mutations in the auxin transport/signalling genes PIN1, PID and ETT [11].
• Here we show that the PINOID gene is inducible by auxin and that the protein kinase is present in the primordia of cotyledons, leaves and floral organs and in vascular tissue in developing organs or proximal to meristems [9].
• Our results indicate that TCH3 and PBP1 interact with the PID protein kinase and regulate the activity of this protein in response to changes in calcium levels [12].

References