Exocyst is an evolutionarily conserved vesicle tethering complex functioning especially in the last stage of exocytosis. Homologs of its eight canonical subunits - Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70, and Exo84 - were found also in higher plants and confirmed to form complexes in vivo, and to participate in cell growth including polarized expansion of pollen tubes and root hairs. Here we present results of a phylogenetic study of land plant exocyst subunits encoded by a selection of completely sequenced genomes representing a variety of plant, mostly angiosperm, lineages. According to their evolution histories, plant exocyst subunits can be divided into several groups. The core subunits Sec6, Sec8, and Sec10, together with Sec3 and Sec5, underwent few, if any fixed duplications in the tracheophytes (though they did amplify in the moss Physcomitrella patens), while others form larger families, with the number of paralogs ranging typically from two to eight per genome (Sec15, Exo84) to several dozens per genome (Exo70). Most of the diversity, which can be in some cases traced down to the origins of land plants, can be attributed to the peripheral subunits Exo84 and, in particular, Exo70. As predicted previously, early land plants (including possibly also the Rhyniophytes) encoded three ancestral Exo70 paralogs which further diversified in the course of land plant evolution. Our results imply that plants do not have a single "Exocyst complex" - instead, they appear to possess a diversity of exocyst variants unparalleled among other organisms studied so far. This feature might perhaps be directly related to the demands of building and maintenance of the complicated and spatially diverse structures of the endomembranes and cell surfaces in multicellular land plants.

Department of Experimental Plant Biology Faculty of Sciences Charles University Prague Czech Republic

Institute of Experimental Botany Academy of Sciences of the Czech Republic Prague Czech Republic

Zobrazit více v PubMed

Anisimova M., Gascuel O. (2006). Approximate likelihood ratio test for branchs: a fast, accurate and powerful alternative. Syst. Biol. 55, 539–552.10.1080/10635150600755453 PubMed DOI

Awashi S., Palmer R., Castro M., Mobarak C. D., Ruby S. W. (2001). New roles for the Snp1 and Exo84 proteins in yeast pre-mRNA splicing. J. Biol. Chem. 276, 31004–31015.10.1074/jbc.M100022200 PubMed DOI

Benson D. A., Karsch-Mizrachi I., Clark K., Lipman D. J., Ostell J., Sayers E. W. (2012). GenBank. Nucleic Acids Res. 40, D48–D53.10.1093/nar/gkr1299 PubMed DOI PMC

Bombarely A., Menda N., Buels R. M., Strickler S., Fischer-York T., Pujar A., Leto J., Gosselin J., Mueller L. A. (2011). The sol genomics network (solgenomics.net): growing tomatoes using perl. Nucleic Acids Res. 39, D1149–D1155. PubMed PMC

Chong Y. T., Gidda S. K., Sanford C., Parkinson J., Mullen R. T., Goring D. R. (2010). Characterization of the Arabidopsis thaliana exocyst complex gene families by phylogenetic, expression profiling, and subcellular localization studies. New Phytol. 185, 401–419.10.1111/j.1469-8137.2009.03070.x PubMed DOI

Cole R. A., Synek L., Žárskýý V., Fowler J. E. (2005). SEC8, a subunit of the putative Arabidopsis exocyst complex, facilitates pollen germination and competitive pollen tube growth. Plant Physiol. 138, 2005–2018.10.1104/pp.105.062273 PubMed DOI PMC

Croteau N. J., Furgason M. L. M., Devos D., Munson M. (2009). Conservation of helical bundle structure between the exocyst subunits. PLoS ONE 4, e4443.10.1371/journal.pone.0004443 PubMed DOI PMC

Dellago H., Löscher M., Ajuh P., Ryder U., Kaisermayer C., Grillari-Voglauer R., Fortschegger K., Gross S., Gstraunthaler A., Borth N., Eisenhaber F., Lamond A. I., Grillari J. (2011). Exo70, a subunit of the exocyst complex, interacts with SNEV(hPrp19/hPso4) and is involved in pre-mRNA splicing. Biochem. J. 438, 81–91.10.1042/BJ20110183 PubMed DOI PMC

Dereeper A., Guignon V., Blanc G., Audic S., Buffet S., Chevenet F., Dufayard J. F., Guindon S., Lefort V., Lescot M., Claverie J. M., Gascuel O. (2008). Phylogeny.fr: robust phylogenetic analysis for the non-specialist. Nucleic Acids Res. 36, W465–W469. PubMed PMC

Eliáš M., Drdová E., Žiak D., Bavlnka B., Hála M., Cvrčková F., Soukupová H., Žárskýý V. (2003). The exocyst complex in plants. Cell Biol. Int. 27, 199–201.10.1016/S1065-6995(02)00349-9 PubMed DOI

Fendrych M., Synek L., Pečenková T., Toupalová H., Cole N., Drdová E., Nebesářová J., Šedinová M., Hála M., Fowler J. E., Žárskýý V. (2010). The Arabidopsis exocyst complex is involved in cytokinesis and cell plate maturation. Plant Cell 22, 3053–3065.10.1105/tpc.110.074351 PubMed DOI PMC

Genre A., Ivanov S., Fendrych M., Faccio A., Žárskýý V., Bisseling T., Bonfante P. (2012). Multiple exocytotic markers accumulate at the sites of perifungal membrane biogenesis in arbuscular mycorrhizas. Plant Cell Physiol. 53, 244–255.10.1093/pcp/pcr170 PubMed DOI

Goodstein D. M., Shu S., Howson R., Neupane R., Hayes R. D., Fazo J., Mitros T., Dirks W., Hellsten U., Putnam N., Rokshar D. S. (2012). Phytozome: a comparative platform for green plant genomics. Nucleic Acids Res. 40, D1178–D1186.10.1093/nar/gkr944 PubMed DOI PMC

Grunt M., Žárskýý V., Cvrčková F. (2008). Roots of angiosperm formins: the evolutionary history of plant FH2 domain-containing proteins. BMC Evol. Biol. 8, 115.10.1186/1471-2148-8-115 PubMed DOI PMC

Guindon S., Gascuel O. (2003). A simple, fast an accurate algorithm to estimate large phylogenies by maximum likelihood. Syst. Biol. 52, 696–704.10.1080/10635150390235520 PubMed DOI

Guo W., Grant A., Novick P. (1999). Exo84p is an exocyst protein essential for secretion. J. Biol. Chem. 274, 23558–23564.10.1074/jbc.274.42.30303 PubMed DOI

Guo W., Roth D., Gatti E., Novick P. (1997). Identification and characterization of homologues of the exocyst component Sec10p. FEBS Lett. 404, 135–139.10.1016/S0014-5793(97)00109-9 PubMed DOI

Hála M., Cole R. A., Synek L., Drdová E., Pečenková T., Nordheim A., Lamkemeyer T., Madlung J., Hochholdinger F., Fowler J. E., Žárskýý V. (2008). An exocyst complex functions in plant cell growth in Arabidopsis and tobacco. Plant Cell 20, 1330–1345.10.1105/tpc.108.059105 PubMed DOI PMC

Hall T. A. (1999). BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl. Acids Symp. Ser. 41, 95–98.

He B., Guo W. (2009). The exocyst complex in polarized exocytosis. Curr. Opin. Cell Biol. 21, 537–542.10.1016/j.ceb.2009.08.008 PubMed DOI PMC

He B., Xi F., Zhang X., Zhang J., Guo W. (2007). Exo70 interacts with phospholipids and mediates the targeting of the exocyst to the plasma membrane. EMBO J. 26, 4053–4065.10.1038/sj.emboj.7601907 PubMed DOI PMC

Heider M. R., Munson M. (2012). Exorcising the exocyst complex. Traffic 13, 898–907.10.1111/j.1600-0854.2012.01353.x PubMed DOI PMC

Hertzog M., Chavrier P. (2011). Cell polarity during motile processes: keeping on track with the exocyst complex. Biochem. J. 433, 403–409.10.1042/BJ20101214 PubMed DOI

Jiao Y., Wickett N. J., Ayyampalayam S., Chanderbali A. S., Landherr L., Ralph P. E., Tomsho L. P., Hu Y., Liang H., Soltis P. S., Soltis D. E., Clifton S. W., Schlarbaum S. E., Schuster S. C., Ma H., Leebens-Mack J., de Pamphilis C. W. (2011). Ancestral polyploidy in seed plants and angiosperms. Nature 473, 97–100.10.1038/nature09916 PubMed DOI

Juan D., Pazos F., Valencia A. (2008). Co-evolution and co-adaptation in protein networks. FEBS Lett. 582, 1225–1230.10.1016/j.febslet.2008.02.017 PubMed DOI

Kee Y., Yoo J. S., Hazuka C. D., Peterson K. E., Hsu S. C., Scheller R. H. (1997). Subunit structure of the mammalian exocyst complex. Proc. Natl. Acad. Sci. U.S.A. 94, 14438–14443.10.1073/pnas.94.26.14438 PubMed DOI PMC

Kitashiba H., Liu P., Nishio T., Nasrallah J. B., Nasrallah M. E. (2011). Functional test of Brassica self-incompatibility modifiers in Arabidopsis thaliana. Proc. Natl. Acad. Sci. U.S.A. 108, 18173–18178.10.1073/pnas.1115283108 PubMed DOI PMC

Koch M. A., Haubold B., Mitchell-Olds T. (2000). Comparative evolutionary analysis of chalcone synthase and alcohol dehydrogenase loci in Arabidopsis, Arabis, and related genera (Brassicaceae). Mol. Biol. Evol. 17, 1483–1498.10.1093/oxfordjournals.molbev.a026248 PubMed DOI

Koumandou V. L., Dacks J. B., Coulson R. M., Field M. C. (2007). Control systems for membrane fusion in the ancestral eukaryote; evolution of tethering complexes and SM proteins. BMC Evol. Biol. 7, 29.10.1186/1471-2148-7-29 PubMed DOI PMC

Kulich I., Cole R. A., Drdová E., Cvrčková F., Soukup A., Fowler J. E., Žárskýý V. (2010). Arabidopsis exocyst subunits SEC8 and EXO70A1 and exocyst interactor ROH1 are involved in the localized deposition of seed coat pectin. New Phytol. 188, 615–625.10.1111/j.1469-8137.2010.03372.x PubMed DOI

Lamesch P., Berardini T. Z., Li D., Swarbreck D., Wilks C., Sasidharan R., Muller R., Dreher K., Alexander D. L., Garcia-Hernandez M., Karthikeyan A. S., Lee C. H., Nelson W. D., Ploetz L., Singh S., Wensel A., Huala E. (2012). The Arabidopsis information resource (TAIR): improved gene annotation and new tools. Nucleic Acids Res. 40, D1202–D1210.10.1093/nar/gkr1090 PubMed DOI PMC

Lang D., Eisinger J., Reski R., Rensing S. (2005). Representation and high-quality annotation of the Physcomitrella patens transcriptome demonstrates a high proportion of proteins involved in metabolism among mosses. Plant Biol. 7, 238–250.10.1055/s-2005-837578 PubMed DOI

Lassmann T., Sonnhammer E. L. (2006). Kalign, Kalignvu and Mumsa: web servers for multiple sequence alignment. Nucleic Acids Res. 34, W596–W599.10.1093/nar/gkl191 PubMed DOI PMC

Lawrence C. E., Altschul S. F., Boguski M. S., Liu J. S., Neuwald A. F., Wootton J. C. (1993). Detecting subtle sequence signals: a Gibbs sampling strategy for multiple alignment. Science 262, 208–214.10.1126/science.8211139 PubMed DOI

Lovell S. C., Robertson D. L. (2010). An integrated view of molecular co-evolution in protein-protein interactions. Mol. Biol. Evol. 27, 2567–2575.10.1093/molbev/msq144 PubMed DOI

McGinnis S., Madden T. L. (2004). BLAST: at the core of a powerful and diverse set of sequence analysis tools. Nucleic Acids Res. 32, W20–W25.10.1093/nar/gnh003 PubMed DOI PMC

Munson M., Novick P. (2006). The exocyst defrocked, a framework of rods revealed. Nat. Struct. Mol. Biol. 13, 577–581.10.1038/nsmb1097 PubMed DOI

Pečenková T., Hála M., Kulich I., Kocourková D., Drdová E., Fendrych M., Toupalová H., Žárskýý V. (2011). The role for the exocyst complex subunits Exo70B2 and Exo70H1 in the plant-pathogen interaction. J. Exp. Bot. 62, 2107–2116.10.1093/jxb/erq402 PubMed DOI PMC

Potato Genome Sequencing Consortium. (2011). Genome sequence and analysis of the tuber crop potato. Nature 475, 189–195.10.1038/nature10158 PubMed DOI

Samuel M. A., Chong Y. T., Haasen K. E., Aldea-Brydges M. G., Stone S. L., Goring D. R. (2009). Cellular pathways regulating responses to compatible and self-incompatible pollen in Brassica and Arabidopsis stigmas intersect at Exo70A1, a putative component of the exocyst complex. Plant Cell 21, 2655–2671.10.1105/tpc.109.069740 PubMed DOI PMC

Schuler G. D., Altschul S. F., Lipman D. J. (1991). A workbench for multiple alignment construction analysis. Proteins 9, 180–190.10.1002/prot.340090304 PubMed DOI

Seguí-Simmaro J. M., Austin J. R., White E. A., Staehelin L. A. (2004). Electron tomographic analysis of somatic cell plate formation in meristematic cells of Arabidopsis preserved by high-pressure freezing. Plant Cell 16, 836–856.10.1105/tpc.017749 PubMed DOI PMC

Sklarczyk D., Franceschini A., Kuhn M., Simonovic M., Roth A., Minguez P., Doerks T., Stark M., Muller J., Bork P., Jensen L. J., von Mering C. (2011). The STRING database in 2011: functional interaction networks of proteins, globally integrated and scored. Nucleic Acids Res. 39, D561–D568.10.1093/nar/gkq973 PubMed DOI PMC

Soltis D. E., Bell C. D., Kim S., Soltis P. S. (2008). Origin and early evolution of angiosperms. Ann. N. Y. Acad. Sci. 1133, 3–25.10.1196/annals.1438.005 PubMed DOI

Songer J. A., Munson M. (2009). Sec6p anchors the assembled exocyst aomplex at sites of secretion. Mol. Biol. Cell 20, 973–982.10.1091/mbc.E08-09-0968 PubMed DOI PMC

Stern A., Doron-Faigenboim A., Erez E., Martz E., Bacharach E., Pupko T. (2007). Selecton 2007: advanced models for detecting positive and purifying selection using a Bayesian inference approach. Nucleic Acids Res. 35, W506–W511.10.1093/nar/gkl818 PubMed DOI PMC

Synek L., Schlager N., Eliáš M., Quentin M., Hauser M. T., Žárskýý V. (2006). AtEXO70A1, a member of a family of putative exocyst subunits specifically expanded in land plants, is important for polar growth and plant development. Plant J. 48, 54–72.10.1111/j.1365-313X.2006.02854.x PubMed DOI PMC

Tamura K., Peterson D., Peterson N., Stecher G., Nei M., Kumar S. (2011). MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol. Biol. Evol. 28, 2731–2739.10.1093/molbev/msr121 PubMed DOI PMC

TerBush D. R., Maurice T., Roth D., Novick P. (1996). The exocyst is a multiprotein complex required for exocytosis in Saccharomyces cerevisiae. EMBO J. 15, 6483–6494. PubMed PMC

The Uniprot Consortium. (2012). Reorganizing the protein space at the Universal Protein Resource (UniProt). Nucleic Acids Res. 40, D71–D75.10.1093/nar/gks060 PubMed DOI PMC

Thompson J. D., Gibson T. J., Plewniak F., Jeanmougin F., Higgins D. G. (1997). The ClustalX windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res. 24, 4876–4882.10.1093/nar/25.24.4876 PubMed DOI PMC

Van de Peer Y., Maere S., Meyer A. (2009). The evolutionary significance of ancient genome duplications. Nat. Rev. Genet. 10, 725–732.10.1038/nrg2600 PubMed DOI

Wang J., Ding Y., Wang J., Hillmer S., Miao Y., Lo S. W., Wang X., Robinson D. G., Jiang L. (2010). EXPO, an exocyst-positive organelle distinct from multivesicular endosomes and autophagosomes, mediates cytosol to cell wall exocytosis in Arabidopsis and tobacco cells. Plant Cell 22, 4009–4030.10.1105/tpc.110.080697 PubMed DOI PMC

Wen T. J., Hochholdinger F., Sauer M., Bruce W., Schnable P. S. (2005). The roothairless1 gene of maize encodes a homolog of sec3, which is involved in polar exocytosis. Plant Physiol. 138, 1637–1643.10.1104/pp.105.062174 PubMed DOI PMC

Whyte J. R., Munro S. (2002). Vesicle tethering complexes in membrane traffic. J. Cell Sci. 115, 2627–2657. PubMed

Woodhouse M. R., Tang H., Freeling M. (2011). Different gene families in Arabidopsis thaliana transposed in different epochs and at different frequencies throughout the rosids. Plant Cell 23, 4241–4253.10.1105/tpc.111.093567 PubMed DOI PMC

Žárskýý V., Cvrčková F., Potocký M., Hála M. (2009). Exocytosis and cell polarity in plants – exocyst and recycling domains. New Phytol. 183, 255–272.10.1111/j.1469-8137.2009.02880.x PubMed DOI

Žárskýý V., Potocký M. (2010). Recycling domains in plant cell morphogenesis: small GTPase effectors, plasma membrane signalling and the exocyst. Biochem. Soc. Trans. 38, 723–728.10.1042/BST0380723 PubMed DOI

Zhang X., Zajac A., Zhang J., Wang P., Li M., Murray J., TerBush D. R., Guo W. (2005). The critical role of Exo84p in the organization and polarized localization of the exocyst complex. J. Biol. Chem. 280, 20356–20364.10.1074/jbc.M414674200 PubMed DOI

Zhang Y., Liu C. M., Emons A. M. C., Ketelaar T. (2010). The plant exocyst. J. Integr. Plant Biol. 52, 138–146.10.1111/j.1744-7909.2010.00929.x PubMed DOI

Interplay of EXO70 and MLO proteins modulates trichome cell wall composition and susceptibility to powdery mildew

A lineage-specific Exo70 is required for receptor kinase-mediated immunity in barley

Plasma membrane phospholipid signature recruits the plant exocyst complex via the EXO70A1 subunit

Functional Specialization within the EXO70 Gene Family in Arabidopsis

EXO70A2 Is Critical for Exocyst Complex Function in Pollen Development

Synergy among Exocyst and SNARE Interactions Identifies a Functional Hierarchy in Secretion during Vegetative Growth

Redundant and Diversified Roles Among Selected Arabidopsis thaliana EXO70 Paralogs During Biotic Stress Responses

Regulation of Exocyst Function in Pollen Tube Growth by Phosphorylation of Exocyst Subunit EXO70C2

Evolution of late steps in exocytosis: conservation and specialization of the exocyst complex

Arabidopsis Trichome Contains Two Plasma Membrane Domains with Different Lipid Compositions Which Attract Distinct EXO70 Subunits

Developmental plasticity of Arabidopsis hypocotyl is dependent on exocyst complex function

Exocyst Subunit EXO70H4 Has a Specific Role in Callose Synthase Secretion and Silica Accumulation

RIN4 recruits the exocyst subunit EXO70B1 to the plasma membrane

EXO70C2 Is a Key Regulatory Factor for Optimal Tip Growth of Pollen

Analysis of Exocyst Subunit EXO70 Family Reveals Distinct Membrane Polar Domains in Tobacco Pollen Tubes

Exocyst SEC3 and Phosphoinositides Define Sites of Exocytosis in Pollen Tube Initiation and Growth

Tethering Complexes in the Arabidopsis Endomembrane System

Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition

Dissecting a hidden gene duplication: the Arabidopsis thaliana SEC10 locus

The exocyst at the interface between cytoskeleton and membranes in eukaryotic cells