Year-end Sale % OFF 
Abstract
The serine/threonine protein kinase 3-phosphoinositide-dependent protein kinase 1 (PDK1) is a highly conserved eukaryotic kinase that is a central regulator of many AGC kinase subfamily members. Through its regulation of AGC kinases, PDK1 controls many basic cellular processes, from translation to cell survival. While many of these PDK1-regulated processes are conserved across kingdoms, it is not well understood how PDK1 may have evolved within kingdoms. In order to better understand PDK1 evolution within plants, we have isolated and characterized the PDK1 gene from the moss Physcomitrella patens (PpPDK1), a nonvascular representative of early land plants. PpPDK1 is similar to other plant PDK1s in that it can functionally complement a yeast PDK1 knockout line. However, unlike PDK1 from other plants, the P. patens PDK1 protein does not bind phospholipids due to a lack of the lipid-binding pleckstrin homology domain, which is used for lipid-mediated regulation of PDK1 activity. Sequence analysis of several PDK1 proteins suggests that lipid regulation of PDK1 may not commonly occur in algae and nonvascular land plants. PpPDK1 can phosphorylate AGC kinase substrates from tomato (Solanum lycopersicum) and P. patens at the predicted PDK1 phosphorylation site, indicating that the PpPDK1 substrate phosphorylation site is conserved with higher plants. We have also identified residues within the PpPDK1 kinase domain that affect kinase activity and show that a mutant with highly reduced kinase activity can still confer cell viability in both yeast and P. patens. These studies lay the foundation for further analysis of the evolution of PDK1 within plants.
Highlights
The serine/threonine protein kinase 3-phosphoinositide-dependent protein kinase 1 (PDK1) is a highly conserved eukaryotic kinase that is a central regulator of many AGC kinase subfamily members
Activation loop phosphorylation by PDK1 typically occurs after docking of the phosphorylated hydrophobic motif of the AGC kinase substrate within a pocket located in the small lobe of the PDK1 kinase domain (Biondi et al, 2002)
Regulation of many basic processes in eukaryotic cells occurs through the phosphorylation of several members of the AGC kinase subfamily by PDK1 (Bogre et al, 2003; Bayascas, 2010)
Summary
The serine/threonine protein kinase 3-phosphoinositide-dependent protein kinase 1 (PDK1) is a highly conserved eukaryotic kinase that is a central regulator of many AGC kinase subfamily members. The kinase subfamily known as the AGC kinases is responsible for regulating many basic cellular functions, and these kinases are found in diverse species including yeast, mammals, and plants (Manning et al, 2002; Bogre et al, 2003; Pearce et al, 2010). This group of kinases is named for three of its representatives, cAMPdependent protein kinase 1 (PKA), cGMP-dependent protein kinase (PKG), and protein kinase C (PKC). Even though plants do not produce PtdIns(3,4,5)P3 (Bogre et al, 2003), the PH domain has been shown to bind several phosphoinositides (Deak et al, 1999), but phosphatidic acid appears to be the phospholipid that induces PDK1 activity toward substrates (Anthony et al, 2004, 2006)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
