Profile of Thomas Südhof, James Rothman, and Randy Schekman
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PROFILE PROFILE Profile of Thomas Südhof, James Rothman, and Randy Schekman, 2013 Nobel Laureates in Physiology or Medicine William T. Wickner1 Rothman prepared Golgi from CHO cells Biochemistry Department, Dartmouth Medical School, Dartmouth College, Hanover, that had been infected with vesicular stoma- NH 03755 titis virus (VSV) expressing a major mem- brane protein, the VSV-G protein. These cells lacked a specific glycosyltransferase. The 2013 Nobel Prize in Physiology or of Enzymology. Later, in his own laboratory at Golgi isolated from these cells were incubated Medicine was awarded to Thomas Südhof, Berkeley, he reasoned that baker’s yeast of- with Golgi isolated from uninfected, WT James Rothman, and Randy Schekman for fered all of the advantages for a reductionist CHOcellsthatborethemissingglycosyl- their pioneering studies of membrane vesi- approach to the secretory pathway. In the late transferase, and trafficking between these cle trafficking. In systems as diverse as the 1970s, Schekman and Peter Novick devised an two Golgi allowed the glycosyltransferase to human brain and baker’s yeast and with elegant selection for mutant yeast cells, termed have access to the VSV-G and catalyze its N- approaches from mouse genetics and elec- sec mutants, which were reversibly blocked in acetylglycosylation. This biochemical assay trophysiology to enzymology to powerful secretion (1). They reasoned that cells that (3) required cytosol and ATP, leading to the genetic screens, they have unraveled this were blocked in the path leading to secretory purification of a required N-ethylmaleimide process, illuminating basic cell biology. Their vesicles and cell surface growth, but that con- (NEM)–sensitive soluble ATPase (NSF). studies provide molecular understanding to tinued macromolecular synthesis, would NSF would not bind to Golgi by itself, but neurotransmission, regulated insulin secre- thereby grow dense. Through selecting tem- required a separate protein, the soluble NSF tion, and a host of human diseases. perature-sensitive density mutants, they attachment (to the membrane) protein, In 1974, Palade and de Duve were recog- obtained a cornucopia of sec mutants. These termed SNAP. The discovery that mamma- nized for discovering the secretory pathway were placed in complementation groups, lian and yeast proteins were functionally in- and demonstrating its directionality through their stages of secretion arrest inferred from electron microscopy and pulse/chase kinetics the glycosylation pattern of the retained se- terchangeable (4) revealed a striking conser- vation of trafficking mechanisms. in combination with organelle fractionation. creted enzyme invertase, and they were While Schekman was establishing the Although whole realms of cell biology of characterized morphologically. The initial genetics of trafficking, and Rothman the first comparable complexity were by then un- studies were published in PNAS (2). Novick derstood in some detail, from intermediary went on to discover actin’s role in organelle functional assays, the groups of Tom Südhof, Richard Scheller, and Reinhard Jahn were metabolism to DNA replication, transcrip- movement, the Rab family of trafficking tion, and translation, the catalysts and GTPases, and large Rab-effector tethering taking a more structural approach to identi- mechanisms of the secretory pathway were complexes and their dynamics, while Schek- fying the major synaptic proteins. Südhof completely unknown. In the secretory man’s group developed functional assays of grew up and was educated in Germany, but pathway, newly made proteins are captured trafficking that required SEC-encoded pro- came to the United States to postdoc with in vesicles that bud from the endoplasmic teins and focused on organelle budding, dis- BrownandGoldsteininDallas,andthen reticulum, fuse to the Golgi, and travel covering the coat complex termed COPII. remained as a faculty member. In the late through that organelle into secretory In the same era, Jim Rothman’sgroupwas 1980s and early 1990s, abundant proteins of vesicles that fuse at the plasma membrane. developing biochemical assays of trafficking. the neuronal synapse were cloned and exam- ined for associations (5). Several neurotoxins SchekmanwasborninMinnesotaand Rothman grew up in Massachusetts, gradu- fi grew up in Los Angeles, saving his money as ating from Yale and doing his doctoral stud- were found to be proteases, and the identi - aladforhisfirst microscope and entering ies with the membrane pioneer Eugene cation of the proteins later termed syntaxin – and synaptobrevin as targets of these pro- science fairs. At University of California Los Kennedy at Harvard Medical School. Found- ’ Angeles, he worked with Dan Ray on bacte- ing his own laboratory at Stanford, he too teases, by Montecucco sgroupandothers, fl ’ provided compelling evidence for their direct riophage replication, and then brought this was in uenced by Arthur Kornberg sfocus ’ passion to Stanford for his graduate studies on the power of purifying proteins that reflect role in exocytosis (6). When Südhof sgroup in Arthur Kornberg’s laboratory, the Temple complex biology from in vitro reactions. cloned and sequenced synaptotagmin, they discovered that it has C2 domains similar to the calcium-dependent protein kinase C (7). Recombinant synaptotagmin was found to bind to membranes in a calcium-dependent Author contributions: W.T.W. wrote the paper. The author declares no conflict of interest. Brunger. Jahn. Novick. Rizo-Rey. Rothman. Schekman. Scheller. Südhof. 1E-mail: [email protected]. www.pnas.org/cgi/doi/10.1073/pnas.1319309110 PNAS Early Edition | 1of2 Downloaded by guest on October 2, 2021 manner (8), andthisproteinwasestablishedas to bound proteins such as Munc13 and What do these three brilliant scientists hon- the major synaptic calcium sensor by an ele- Munc18 for synaptic fusion and by Sec1/ ored with this year’s Nobel award share in gant combination of electrophysiology of Munc18 homologs and large tethering common? Short, tall, East coast, West coast, knock-in mice with mutant synaptotagmin (9). complexes for many other intracellular thin, less-thin—no common feature meets the In a signal contribution, Rothman’sgroup SNARE-dependent membrane fusion events. eye. However, each is scientifically fearless and found that immobilized, purified SNAP that Reconstituted reactions reflecting more of passionately in love with science, each conveys was incubated with detergent extract of the complete physiological complexity, his full enthusiasm and brilliance in lectures, whole brain selectively bound syntaxin and regulation, and kinetics have appeared and each is endowed with wonderful humor synaptobrevin proteins, and NSF and ATP (14–17). The neuronal fusion reconstitu- and personal charm. It is this full devotion, were then required for their release (10). tion is strictly dependent on Munc18- and joy in the work, that unites this year’s These proteins were termed soluble NEM- 1and Munc13 (17), in full accord with Nobelists, with each other and with their sensitive factor receptor, or SNARE pro- Südhof’sgroup’s findings. many friends and admirers around the world. teins. Reinhard Jahn, with colleagues Dirk Fasshauer and Axel Brunger, showed that SNAREs with their characteristic heptad 1 Novick P, Field C, Schekman R (1980) Identification of 23 10 Söllner T, et al. (1993) SNAP receptors implicated in vesicle complementation groups required for post-translational events in the targeting and fusion. Nature 362(6418):318–324. repeats can be placed in subfamilies accord- yeast secretory pathway. Cell 21(1):205–215. 11 Fasshauer D, Sutton RB, Brunger AT, Jahn R (1998) Conserved structural ing to the polar arginine or glutamine at 2 Novick P, Schekman R (1979) Secretion and cell-surface growth are features of the synaptic fusion complex: SNARE proteins reclassified as Q- a center of their SNARE domain (11), and blocked in a temperature-sensitive mutant of Saccharomyces and R-SNAREs. Proc Natl Acad Sci USA 95(26):15781–15786. cerevisiae. Proc Natl Acad Sci USA 76(4):1858–1862. 12 Sutton RB, Fasshauer D, Jahn R, Brunger AT (1998) Crystal 3 determined the crystal structure of a complex Balch WE, Dunphy WG, Braell WA, Rothman JE (1984) structure of a SNARE complex involved in synaptic exocytosis at 2.4 A of the four helical SNARE core domains Reconstitution of the transport of protein between successive resolution. Nature 395(6700):347–353. compartments of the Golgi measured by the coupled incorporation 13 Weber T, et al. (1998) SNAREpins: Minimal machinery for (12). Axel Brunger and Reinhard Jahn, to- – of N-acetylglucosamine. Cell 39(2 Pt 1):405 416. membrane fusion. Cell 92(6):759–772. 4 Dunphy WG, et al. (1986) Yeast and mammals utilize similar gether with Fasshauer and Sutton, deter- 14 Mima J, Hickey CM, Xu H, Jun Y, Wickner W (2008) cytosolic components to drive protein transport through the Golgi mined the crystal structure of the complex Reconstituted membrane fusion requires regulatory lipids, complex. Proc Natl Acad Sci USA 83(6):1622–1626. SNAREs and synergistic SNARE chaperones. EMBO J 27(15): of the four helical neuronal SNARE core 5 Trimble WS, Cowan DM, Scheller RH (1988) VAMP-1: A synaptic 2031–2042. domains (12), revealing that SNAREs with vesicle-associated integral membrane protein. Proc Natl Acad Sci 15 Ohya T, et al. (2009) Reconstitution of Rab- and SNARE- USA 85(12):4538–4542. their characteristic heptad repeats can be dependent membrane fusion by synthetic endosomes. Nature 6 Schiavo G, et al. (1992) Tetanus and botulinum-B neurotoxins – placed in subfamilies according to the polar block neurotransmitter release by proteolytic cleavage of 459(7250):1091 1097. 16 arginine or glutamate at the center of the synaptobrevin. Nature 359(6398):832–835. Diao J, et al. (2012) Synaptic proteins promote calcium-triggered 7 Perin MS, Fried VA, Mignery GA, Jahn R, Südhof TC (1990) fusion from point contract to full fusion. eLife 1 e00109. 17 core complex (11). Phospholipid binding by a synaptic vesicle protein homologous to the Ma C, Su L, Seven AB, Xu Y, Rizo J (2013) Reconstitution of the The SNAREs were shown to directly regulatory region of protein kinase C. Nature 345(6272):260–263.