Integrated G Proteins Signaling in Plants PDF
Preview Integrated G Proteins Signaling in Plants
Signaling and Communication in Plants Series Editors FrantisˇekBalusˇka DepartmentofPlantCellBiology,IZMB,UniversityofBonn,Kirschallee1,D-53115 Bonn, Germany JorgeVivanco CenterforRhizosphereBiology,ColoradoStateUniversity,217ShepardsonBuilding, FortCollins, CO 80523-1173,USA For furthervolumes: http://www.springer.com/series/8094 Shaul Yalovsky Frantisˇek Balusˇka Alan Jones l l Editors Integrated G Proteins Signaling in Plants Editors Dr.ShaulYalovsky Dr.FrantisˇekBalusˇka TelAvivUniversity DepartmentofPlantCellBiology Dept.PlantSciences IZMB 69978RamatAviv,TelAviv UniversityofBonn 603BritanniaBldg. Kirschallee1 Israel D-53115Bonn [email protected] Germany [email protected] Dr.AlanJones UniversityofNorthCarolina Dept.Biology&Pharmacology 317CokerHall ChapelHillNC27599 CB3280 USA [email protected] ISSN:1867–9048 e-ISSN:1867–9056 ISBN:978-3-642-03523-4 e-ISBN:978-3-642-03524-1 DOI10.1007/978-3-642-03524-1 SpringerHeidelbergDordrechtLondonNewYork LibraryofCongressControlNumber:2009934482 #Springer-VerlagBerlinHeidelberg2010 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication orpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9, 1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violations areliabletoprosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnot imply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotec- tivelawsandregulationsandthereforefreeforgeneraluse. Coverdesign:WMXDesignGmbH,Heidelberg,Germany Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface When guanine nucleotide-binding proteins (G proteins) bind GTP, they adopt an activatedconformationthatleadstoactivationofdownstream signaling elements. In this capacity, G proteins couple, amplify, and integrate upstream signals to downstreamcellularchanges.OneofthemostfascinatingaspectsofGproteinsis that they operate like a molecular timer because the GTP-bound, activated state convertstotheGDP-bound,restingstateafteraninherentlydeterminedamountof time due to hydrolysis of GTP to GDP by the intrinsic GTPase. The cycling of activatedtorestingstates,knownastheGcycle,enablescellularsignalingtooccur withinkineticsofsecondstohours.Ineukaryotes,Gproteinsaredividedintotwo majorsubgroups:theRassuperfamilyofsmallGproteinsandtheheterotrimericG proteins. The Ras superfamily is further divided into the Ras, Rho, Rab, Arf, and Ransubfamilies.TheGasubunits oftheheterotrimericG-proteincomplexdivide the complexes into four subclasses, G, G, G , and G . The Ras, Rho, and the i s q 12/13 hetrotrimericGproteinsareimplicatedinregulationofsignaling, whileRab,Arf, andRancarryoutothercellularfunctionsandarenotbecoveredinthisbook.Ras proteinshavenotbeenidentifiedinplants.ThisleavesthesmallGproteinfromthe Rhofamily,calledROPsorRACs(hereafterROPs/RACs),andtheheterotrimeric GproteinstocomprisethetwomajorgroupsofsignalingGproteinsinplants.This book summarizes a decade of research on ROPs/RACs and heterotrimeric G proteinsinplants. In the active state, the small GTPases interact with target proteins commonly referredtoaseffectorstoinitiateasignalingprocess.InmostsmallGproteins,the GDP/GTP exchange is not spontaneous and requires accessory proteins known as GunaninenucleotideExchangeFactors(GEFs).TheinefficientGTPaseactivityis enhance by a second group of proteins known as GTPase Activating Proteins (GAPs). GEFs and GAPs provide a means to regulate the activity of the small GTPasesintimeandspace.SubcellulardistributionofproteinsfromRhoandRab families is regulated by a third group of proteins designated Guanine nucleotide DissociationInhibitors(GDIs). v vi Preface HeterotrimericGproteinarecomposedofthreesubunitsdesignateda,b,andg. The a subunit is a GTP-binding protein that contains one domain that resembles small GTPases. The b subunit has a seven-bladed propeller structure and forms a tightdimericcomplexwiththegsubunit.Inmetazoans,heterotrimericGproteins are associated with membrane proteins known as G-Protein-Coupled Receptors (GPCRs) that are the ligand-regulated GEFs. Activation of GPCRs upon ligand bindingleadstoGDP/GTPexchangeandactivationoftheGa.Inturn,Gb-andGg dissociate from the subunit as a complex and signaling is induced by both the dissociated Ga and Gb g complex. Signaling terminates by GTP hydrolysis that leadstoreassociationofGbgwiththeGa.AsdiscussedintheChapter“Bioinfor- matics of Seven-Transmembrane Receptors in Plant Genomes,” the existence of GPCRsinplantsisquestioned. Furthermore, as discussed in the Chapter “Plant Ga Structure and Properties,” while GDP release from the Ga subunit is the rate-limiting step in vertebrate G proteincomplexes,thatdoesnotseemtobethecaseforArabidopsis.Theimplica- tionsofthisstrangepropertyaredescribed. ThebookbeginswithachapterfromJaniceJonesdescribingtheseandotherG protein signaling principles and then describes the unique properties of plant heterotrimeric G proteins. The chapter “Structure and function of ROPs and their GEFs,” by ChristophThomas and Antje Berken takes a similar approach with the smallGproteinsandthus,thesetwochaptersprovideaninterestingcomparisonof theGasubunitoftheheterotrimericGproteincomplexandthesmallGproteinsin plants. Physiological aspects are taken up in later chapters. For example, in the Chapter “Heterotrimeric G Proteins and Plant Hormone Signaling in Rice,” by YukimotoIwasakiandcoworkers,evidenceispresentedthattheGproteininriceis mediating fundamantally different signaling than in Arabidopsis. Jin-Gui Chen in theChapter“HeterotrimericG-ProteinsandCellDivisioninPlants,”buildsthecase that the heterotrimeric G protein complex controls the rate of the plant cell cycle andconsequentlycellproliferation.Twochapters(“TheRoleofSevenTransmem- brane Domain MLO Proteins, Heterotrimeric G-Proteins and Monomeric RAC/ ROPs in Plant Defense” and “G Proteins and Plant Innate Immunity”) by Justine Lorek et al. and Yuri Trusov et al., respectively, deal with the role of small and heterotrimericGproteinsinplantdefenseagainstdifferentpathogens.Whetheror notGproteinscouplemultipleplanthormonesandenvironmentalsignalsremains an open question but is a theme throughout the book. As mentioned earlier, the receptorsthatactivatetheheterotrimericGproteincomplexarepoorlyconservedat the primary sequence level. Therefore, in the Chapter “Bioinformatics of Seven- Transmembrane Receptors in Plant Genomes,” Etsuyko Moriyma and Stephen Opiyo provide strategies to identify 7-transmembrane proteins from divergent genomes. They then apply these tools to 18 genomes of the bikonts, the group that includes higher plants and the algae. The chapter “Evolution of the ROP GTPase Signaling Module” is about the bizaar; Lei Ding and coworkers discuss Preface vii proteins that share limited sequence similarity to canonical Ga subunits of the heterotrimericGproteincomplex. ROPs/RACs aremasterregulators ofcell polarity, similartotheir homologsin yeast and animal cells. Remarkably, these studies showed that regardless of the evolutionary-conservedfunctions,manyoftheROPs/RACseffectorsareuniqueto plants.Thechapter“ROPGTPasesandthecytoskeleton”byYingFufocusesonthe function of ROPs/RACs in cytoskeleton organization, highlighting the role of a plant-uniquegroupofproteinsdesignatedRICs(ROPInteractingCRIBcontaining) as well as by the evolutionary-conserved WAVE and Arp2/3 complexes. In the absenceofothersignalingsmallGTPases,ROPs/RACsweresuggestedtofunction indiversesignalingcascades.Thechapter“RAC/ROPGTPasesintheRegulation ofPolarityandPolarCellGrowth“byHe-MingWuandAliceCheungdescribesthe roleofROPs/RACsincellpolarity,hormonal,andreactiveoxygenspeciessignal- ing.Thechapterhighlightshowconservedmechanismsinvolvingproteinssuchas ADF/cofilinsandforminstogetherwithplant-uniqueproteinssuchastheRICsand ICR1 (Interactor of Constitutive active ROP1) orchestrate polar cell growth. The chapter “The Role of Seven Transmembrane Domain MLO Proteins, Heterotri- meric G-Proteins and Monomeric RAC/ROPs in Plant Defense” by Justine Lorek etal.discussestheroleofROPs/RACsMLOproteinsandhetrotrimericGproteins inplantdefenseresponsesandhowtheyinterfacewithcellpolarity,complementing the discussion in the chapter “G proteins and plant innate immunity.” Two types of ROP/RAC GEFs are currently known in plants: an evolutionary-conserved Dock180 protein called SPIKE1, which may be associated with the WAVE com- plex and a family of proteins designated PRONE GEFs that can activate ROPs/ RACs but not non-plant Rho proteins. In the chapter “Structure and Function of ROPsandTheirGEFs,”ChristophThomasandAntjeBerkendiscussthestructure andfunctionofROPs/RACsandthePRONEROPGEFs,highlightingthecommon and plant-unique features. GAPs and RhoGDIs play pivotal roles in regulation of signaling by Rho GTPases. The chapter “Regulatory and Cellular Functions of Plant RhoGAPsand RhoGDIs” by Benedikt Kost highlights studies showing how spatial distribution of certain GAPs and function of RhoGDIs regulate polar cell growth. The chapter “Evolution of the ROP GTPase Signaling Module” by John FowlerdiscussestheoriginandevolutionofROPs/RACs.ROP/RACsandhetero- trimericGproteinsfunctionattheplasmamembranetowhichtheyattachbyvirtue ofpostranslationallipidmodificationsandpolybasicregioncomprisedoflysineand arginine residues. In the chapter “Protein–lipid Modifications and Targeting of ROP/RAC and Heterotrimeric G Proteins,” Nadav Sorek and Shaul Yalovsky describe the lipid modifications and their regulatory roles in function of ROP/ RACs and heterotrimeric G proteins.Each chapter of this book offers a different perspectiveofthestate-of-the-artinthefield,presentingawell-balancedandanup- to-datedescriptionofthecurrentknowledgeonGproteinsignalinginplants.The breadthofthebookoffersathouroughintroduction,andatthesametime,adetailed in-depth discussion to those who are new to the field. Thus, we hope to draw the viii Preface interest of both new and advanced students to this relatively young but fast- progressingandfascinatingfieldofplantcellbiology TelAviv,June2009 ShaulYalovsky Bonn,June2009 FrantisˇekBalusˇka ChapelHill,June2009 AlanJones Contents PlantGaStructureandProperties ........................................... 1 Janice C. Jones RegulatoryandCellularFunctionsofPlantRhoGAPs andRhoGDIs ................................................................ 27 Benedikt Kost StructureandFunctionofROPsandtheirGEFs ........................... 49 Christoph Thomas and Antje Berken Protein–LipidModificationsandTargetingofROP/RAC andHeterotrimericGProteins .............................................. 71 Nadav Sorek and Shaul Yalovsky ROPGTPasesandtheCytoskeleton ........................................ 91 Ying Fu RAC/ROPGTPasesintheRegulationofPolarity andPolarCellGrowth ...................................................... 105 Hen-mingWu,ChristineY.Chen,QiaohongDuan,DanielKita, CandidaNibau,Li-zhenTao,Yan-jiaoZou,andAliceY.Cheung HeterotrimericGProteinsandPlantHormoneSignalinginRice .......... 123 KatsuyukiOki,YukikoFujisawa,HisaharuKato, andYukimotoIwasaki Auxin,Brassinosteroids,andG-ProteinSignaling .......................... 135 Lei Wang and Kang Chong HeterotrimericG-ProteinsandCellDivisioninPlants ..................... 155 Jin-Gui Chen ix x Contents HeterotrimericGProteinRegulationofStomatalMovements ............. 177 Sarah E. Nilson and Wei Zhang TheRoleofSeven-TransmembraneDomainMLOProteins, HeterotrimericG-Proteins,andMonomericRAC/ROPs inPlantDefense ............................................................ 197 Justine Lorek, Ralph Panstruga, and Ralph Hu¨ckelhoven GProteinsandPlantInnateImmunity ..................................... 221 Yuri Trusov, Lucı´a Jorda´, Antonio Molina, and Jose Ramon Botella BioinformaticsofSeven-TransmembraneReceptors inPlantGenomes ........................................................... 251 Etsuko N. Moriyama and Stephen O. Opiyo UnconventionalGTP-BindingProteinsinPlants ........................... 279 LeiDing,TimothyE.Gookin,andSarahM.Assmann EvolutionoftheROPGTPaseSignalingModule .......................... 305 JohnE.Fowler Index ........................................................................ 329 Plant Ga Structure and Properties JaniceC.Jones Abstract G-protein-coupled receptors (GPCRs) are a large family of eukaryotic membrane-spanning proteins that convert signals from the outside of a cell to an appropriate response inside the cell. GPCRs typically associate with a heterotri- meric Gabg protein. Activated receptors propagate signals by causing the Ga subunit of the heterotrimer to release GDP and to bind GTP. GTP binding causes a conformational change in the Ga protein that triggers heterotrimer dissociation anddownstreamsignaling.Inthisway,theguaninenucleotideoccupancyoftheGa subunit determines the protein structure and activity. Although most of the G protein paradigm has been established by studying animal G proteins, recent researchhasrevealeddiverserolesforGproteinsignalinginplants.Thefirstpart of the chapter (Section “Introduction: Structure-Function Relationships in G Pro- teinSignaling”inChapter“PlantGaStructureandProperties”)reviewsGprotein signaling principles, with an emphasis on the information that has been gleaned fromatomicstructures.Thesecondpart(Section“ComparisonofPlantGaProteins to Mammalian Ga Proteins” in Chapter, “Plant Ga Structure and Properties”) compares plant Ga proteins to animal Ga proteins with an emphasis on how structureconfersfunctionfortheseproteins.AlthoughplantandanimalGaproteins share less than 40% identity, the key residues that confer G protein function are nearlyinvariantacrossallGproteinfamilies.Thethirdpart(Section“Propertiesof Plant Ga Proteins” in Chapter “Plant Ga Structure and Properties”) describes the physicalpropertiesofplantGaproteins,includingkineticproperties,localization, receptorcoupling,andeffectoractivation. J.C.Jones DivisionofBiochemistryandBiophysics,DepartmentofBiology,UniversityofNorthCarolina, POBox7260,ChapelHill,NC27599,USA e-mail:[email protected] S.Yalovskyetal.(eds.),IntegratedGProteinsSignalinginPlants, 1 SignalingandCommunicationinPlants, DOI10.1007/978-3-642-03524-1_1,#Springer-VerlagBerlinHeidelberg2010
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