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Author Yogev, O.; Yogev, O.; Singer, E.; Shaulian, E.; Goldberg, M.; Fox, T.D.; Pines, O. file  url
openurl 
  Title Fumarase: a mitochondrial metabolic enzyme and a cytosolic/nuclear component of the DNA damage response Type Journal Article
  Year 2010 Publication PLoS Biology Abbreviated Journal PLoS Biol  
  Volume 8 Issue 3 Pages (down) e1000328  
  Keywords Cell Nucleus/*metabolism; Cytosol/*metabolism; *DNA Damage; Fumarate Hydratase/genetics/*metabolism; Fumarates/metabolism; Gene Knockdown Techniques; HeLa Cells; Histones/genetics/metabolism; Humans; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism; Isoenzymes/genetics/*metabolism; Kidney Neoplasms/enzymology/genetics; Leiomyomatosis/enzymology/genetics; Mitochondria/*enzymology; Saccharomyces cerevisiae/enzymology/genetics; Saccharomyces cerevisiae Proteins/genetics/metabolism; Tumor Suppressor Proteins/genetics/metabolism  
  Abstract In eukaryotes, fumarase (FH in human) is a well-known tricarboxylic-acid-cycle enzyme in the mitochondrial matrix. However, conserved from yeast to humans is a cytosolic isoenzyme of fumarase whose function in this compartment remains obscure. A few years ago, FH was surprisingly shown to underlie a tumor susceptibility syndrome, Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC). A biallelic inactivation of FH has been detected in almost all HLRCC tumors, and therefore FH was suggested to function as a tumor suppressor. Recently it was suggested that FH inhibition leads to elevated intracellular fumarate, which in turn acts as a competitive inhibitor of HPH (HIF prolyl hydroxylase), thereby causing stabilization of HIF (Hypoxia-inducible factor) by preventing proteasomal degradation. The transcription factor HIF increases the expression of angiogenesis regulated genes, such as VEGF, which can lead to high microvessel density and tumorigenesis. Yet this mechanism does not fully explain the large cytosolic population of fumarase molecules. We constructed a yeast strain in which fumarase is localized exclusively to mitochondria. This led to the discovery that the yeast cytosolic fumarase plays a key role in the protection of cells from DNA damage, particularly from DNA double-strand breaks. We show that the cytosolic fumarase is a member of the DNA damage response that is recruited from the cytosol to the nucleus upon DNA damage induction. This function of fumarase depends on its enzymatic activity, and its absence in cells can be complemented by high concentrations of fumaric acid. Our findings suggest that fumarase and fumaric acid are critical elements of the DNA damage response, which underlies the tumor suppressor role of fumarase in human cells and which is most probably HIF independent. This study shows an exciting crosstalk between primary metabolism and the DNA damage response, thereby providing a scenario for metabolic control of tumor propagation.  
  Call Number Serial 1880  
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Author Mazzoni, C.; Falcone, C. file  url
openurl 
  Title Caspase-dependent apoptosis in yeast Type Journal Article
  Year 2008 Publication Biochimica et Biophysica Acta Abbreviated Journal Biochim Biophys Acta  
  Volume 1783 Issue 7 Pages (down) 1320-1327  
  Keywords Apoptosis--genetics, physiology; Apoptosis Regulatory Proteins--metabolism; Caspases--metabolism; Mitochondria--metabolism; Saccharomyces cerevisiae--genetics, physiology; Saccharomyces cerevisiae Proteins--metabolism; Signal Transduction  
  Abstract Damaging environment, certain intracellular defects or heterologous expression of pro-apoptotic genes induce death in yeast cells exhibiting typical markers of apoptosis. In mammals, apoptosis can be directed by the activation of groups of proteases, called caspases, that cleave specific substrates and trigger cell death. In addition, in plants, fungi, Dictyostelium and metazoa, paracaspases and metacaspases have been identified that share some homologies with caspases but showing different substrate specificity. In the yeast Saccharomyces cerevisiae, a gene (MCA1/YCA1) has been identified coding for a metacaspase involved in the induction of cell death. Metacaspases are not biochemical, but sequence and functional homologes of caspases, as deletion of them rescues entirely different death scenarios. In this review we will summarize the current knowledge in S. cerevisiae on apoptotic processes, induced by internal and external triggers, which are dependent on the metacaspase gene YCA1.  
  Call Number Serial 850  
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Author Schmidt, B.H.; Osheroff, N.; Berger, J.M. file  url
openurl 
  Title Structure of a topoisomerase II-DNA-nucleotide complex reveals a new control mechanism for ATPase activity Type Journal Article
  Year 2012 Publication Nature Structural & Molecular Biology Abbreviated Journal Nat Struct Mol Biol  
  Volume 19 Issue 11 Pages (down) 1147-1154  
  Keywords Adenylyl Imidodiphosphate/*chemistry/metabolism; Amino Acid Sequence; Antigens, Neoplasm/*chemistry/metabolism; Chromatography, Gel; Crystallization; DNA/*chemistry/metabolism; DNA Topoisomerases, Type II/*chemistry/metabolism; DNA-Binding Proteins/*chemistry/metabolism; Dimerization; *Models, Molecular; Molecular Sequence Data; Multiprotein Complexes/*chemistry/metabolism; *Protein Conformation; Saccharomyces cerevisiae/*enzymology  
  Abstract Type IIA topoisomerases control DNA supercoiling and disentangle chromosomes through a complex ATP-dependent strand-passage mechanism. Although a general framework exists for type IIA topoisomerase function, the architecture of the full-length enzyme has remained undefined. Here we present the structure of a fully catalytic Saccharomyces cerevisiae topoisomerase II homodimer complexed with DNA and a nonhydrolyzable ATP analog. The enzyme adopts a domain-swapped configuration wherein the ATPase domain of one protomer sits atop the nucleolytic region of its partner subunit. This organization produces an unexpected interaction between bound DNA and a conformational transducing element in the ATPase domain, which we show is critical for both DNA-stimulated ATP hydrolysis and global topoisomerase activity. Our data indicate that the ATPase domains pivot about each other to ensure unidirectional strand passage and that this state senses bound DNA to promote ATP turnover and enzyme reset.  
  Call Number Serial 2189  
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Author Bieling, P.; Laan, L.; Schek, H.; Munteanu, E.L.; Sandblad, L.; Dogterom, M.; Brunner, D.; Surrey, T. file  url
openurl 
  Title Reconstitution of a microtubule plus-end tracking system in vitro Type Journal Article
  Year 2007 Publication Nature Abbreviated Journal Nature  
  Volume 450 Issue 7172 Pages (down) 1100-1105  
  Keywords  
  Abstract The microtubule cytoskeleton is essential to cell morphogenesis. Growing microtubule plus ends have emerged as dynamic regulatory sites in which specialized proteins, called plus-end-binding proteins (+TIPs), bind and regulate the proper functioning of microtubules. However, the molecular mechanism of plus-end association by +TIPs and their ability to track the growing end are not well understood. Here we report the in vitro reconstitution of a minimal plus-end tracking system consisting of the three fission yeast proteins Mal3, Tip1 and the kinesin Tea2. Using time-lapse total internal reflection fluorescence microscopy, we show that the EB1 homologue Mal3 has an enhanced affinity for growing microtubule end structures as opposed to the microtubule lattice. This allows it to track growing microtubule ends autonomously by an end recognition mechanism. In addition, Mal3 acts as a factor that mediates loading of the processive motor Tea2 and its cargo, the Clip170 homologue Tip1, onto the microtubule lattice. The interaction of all three proteins is required for the selective tracking of growing microtubule plus ends by both Tea2 and Tip1. Our results dissect the collective interactions of the constituents of this plus-end tracking system and show how these interactions lead to the emergence of its dynamic behaviour. We expect that such in vitro reconstitutions will also be essential for the mechanistic dissection of other plus-end tracking systems.

Subject Heading: Cell-Free System; Heat-Shock Proteins/metabolism; Intermediate Filament Proteins/metabolism; Microscopy, Fluorescence; Microtubule-Associated Proteins/*metabolism; Microtubules/*chemistry/*metabolism; *Schizosaccharomyces/chemistry/cytology; Schizosaccharomyces pombe Proteins/metabolism
 
  Call Number Serial 2223  
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Author Gupta, M.L.J.; Carvalho, P.; Roof, D.M.; Pellman, D. file  url
openurl 
  Title Plus end-specific depolymerase activity of Kip3, a kinesin-8 protein, explains its role in positioning the yeast mitotic spindle Type Journal Article
  Year 2006 Publication Nature Cell Biology Abbreviated Journal Nat Cell Biol  
  Volume 8 Issue 9 Pages (down) 913-923  
  Keywords  
  Abstract The budding yeast protein Kip3p is a member of the conserved kinesin-8 family of microtubule motors, which are required for microtubule-cortical interactions, normal spindle assembly and kinetochore dynamics. Here, we demonstrate that Kip3p is both a plus end-directed motor and a plus end-specific depolymerase--a unique combination of activities not found in other kinesins. The ATPase activity of Kip3p was activated by both microtubules and unpolymerized tubulin. Furthermore, Kip3p in the ATP-bound state formed a complex with unpolymerized tubulin. Thus, motile kinesin-8s may depolymerize microtubules by a mechanism that is similar to that used by non-motile kinesin-13 proteins. Fluorescent speckle analysis established that, in vivo, Kip3p moved toward and accumulated on the plus ends of growing microtubules, suggesting that motor activity brings Kip3p to its site of action. Globally, and more dramatically on cortical contact, Kip3p promoted catastrophes and pausing, and inhibited microtubule growth. These findings explain the role of Kip3p in positioning the mitotic spindle in budding yeast and potentially other processes controlled by kinesin-8 family members.

Subject headings: Adenosine Triphosphatases/metabolism; Cell Cycle/physiology; Kinesin/*metabolism; Microtubule-Associated Proteins/*physiology; Microtubules/*physiology; Molecular Motor Proteins/*physiology; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins/*physiology; Spindle Apparatus/*physiology; Tubulin/metabolism
 
  Call Number Serial 2212  
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Author Gupta, M.L.J.; Carvalho, P.; Roof, D.M.; Pellman, D. file  url
openurl 
  Title Plus end-specific depolymerase activity of Kip3, a kinesin-8 protein, explains its role in positioning the yeast mitotic spindle Type Journal Article
  Year 2006 Publication Nature Cell Biology Abbreviated Journal Nat Cell Biol  
  Volume 8 Issue 9 Pages (down) 913-923  
  Keywords  
  Abstract The budding yeast protein Kip3p is a member of the conserved kinesin-8 family of microtubule motors, which are required for microtubule-cortical interactions, normal spindle assembly and kinetochore dynamics. Here, we demonstrate that Kip3p is both a plus end-directed motor and a plus end-specific depolymerase--a unique combination of activities not found in other kinesins. The ATPase activity of Kip3p was activated by both microtubules and unpolymerized tubulin. Furthermore, Kip3p in the ATP-bound state formed a complex with unpolymerized tubulin. Thus, motile kinesin-8s may depolymerize microtubules by a mechanism that is similar to that used by non-motile kinesin-13 proteins. Fluorescent speckle analysis established that, in vivo, Kip3p moved toward and accumulated on the plus ends of growing microtubules, suggesting that motor activity brings Kip3p to its site of action. Globally, and more dramatically on cortical contact, Kip3p promoted catastrophes and pausing, and inhibited microtubule growth. These findings explain the role of Kip3p in positioning the mitotic spindle in budding yeast and potentially other processes controlled by kinesin-8 family members.

Subject Headings: Adenosine Triphosphatases/metabolism; Cell Cycle/physiology; Kinesin/*metabolism; Microtubule-Associated Proteins/*physiology; Microtubules/*physiology; Molecular Motor Proteins/*physiology; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins/*physiology; Spindle Apparatus/*physiology; Tubulin/metabolism
 
  Call Number Serial 2260  
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Author Favelukes, G.; Stoppani, A.O. url  openurl
  Title Baker's-yeast fumarase, a thiol enzyme Type Journal Article
  Year 1958 Publication Biochimica et Biophysica Acta Abbreviated Journal Biochim Biophys Acta  
  Volume 28 Issue 3 Pages (down) 654-655  
  Keywords *Hydro-Lyases; Saccharomyces cerevisiae/*metabolism; *Hydrases; *SACCHAROMYCES CEREVISIAE/metabolism  
  Abstract  
  Call Number Grinnell @ engelk @ Serial 483  
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Author Westermann, S.; Wang, H.-W.; Avila-Sakar, A.; Drubin, D.G.; Nogales, E.; Barnes, G. file  url
openurl 
  Title The Dam1 kinetochore ring complex moves processively on depolymerizing microtubule ends Type Journal Article
  Year 2006 Publication Nature Abbreviated Journal Nature  
  Volume 440 Issue 7083 Pages (down) 565-569  
  Keywords  
  Abstract Chromosomes interact through their kinetochores with microtubule plus ends and they are segregated to the spindle poles as the kinetochore microtubules shorten during anaphase A of mitosis. The molecular natures and identities of coupling proteins that allow microtubule depolymerization to pull chromosomes to poles during anaphase have long remained elusive. In budding yeast, the ten-protein Dam1 complex is a critical microtubule-binding component of the kinetochore that oligomerizes into a 50-nm ring around a microtubule in vitro. Here we show, with the use of a real-time, two-colour fluorescence microscopy assay, that the ring complex moves processively for several micrometres at the ends of depolymerizing microtubules without detaching from the lattice. Electron microscopic analysis of 'end-on views' revealed a 16-fold symmetry of the kinetochore rings. This out-of-register arrangement with respect to the 13-fold microtubule symmetry is consistent with a sliding mechanism based on an electrostatically coupled ring-microtubule interface. The Dam1 ring complex is a molecular device that can translate the force generated by microtubule depolymerization into movement along the lattice to facilitate chromosome segregation.

Subject Headings: Cell Cycle Proteins/*physiology; Chromosome Segregation/physiology; Kinetochores/*physiology/ultrastructure; Microscopy, Fluorescence; Microtubule-Associated Proteins/*physiology; Microtubules/*physiology/ultrastructure; Movement; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins/*physiology; Spindle Apparatus/*physiology/ultrastructure
 
  Call Number Serial 2219  
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Author Thacker, C.; Rose, A.M. file  url
doi  openurl
  Title A look at the Caenorhabditis elegans Kex2/Subtilisin-like proprotein convertase family Type Journal Article
  Year 2000 Publication BioEssays : News and Reviews in Molecular, Cellular and Developmental Biology Abbreviated Journal Bioessays  
  Volume 22 Issue 6 Pages (down) 545-553  
  Keywords Animals; Caenorhabditis elegans/*enzymology/genetics; Genes, Helminth; Humans; Multigene Family; Mutation; Phylogeny; *Proprotein Convertases; *Saccharomyces cerevisiae Proteins; Subtilisins/chemistry/genetics/*metabolism  
  Abstract Significant advances have recently been made in our understanding of the mechanisms of activation of proteins that require processing. Often this involves endoproteolytic cleavage of precursor forms at basic residues, and is carried out by a group of serine endoproteinases, termed the proprotein convertases. In mammals, seven different convertases have been identified to date. These act in both the regulated secretory pathway for the processing of prohormones and proneuropeptides and in the constitutive secretory pathway, in which a variety of proproteins are activated endoproteolytically. The recently completed sequence of the nematode Caenorhabditis elegans genome affords a unique opportunity to examine the entire proprotein convertase family in a multicellular organism. Here we review the nature of the family, emphasising the structural features, characteristic of the four nematode genes, that supply all of the necessary functions unique to this group of serine endoproteinases. Studies of the C. elegans genes not only provide important information about the evaluation of this gene family but should help to illuminate the roles of these proteins in mammalian systems. BioEssays 22:545-553, 2000.  
  Call Number Serial 522  
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Author Williams, R.P.; Gott, C.L.; Qadri, S.M.; Scott, R.H. file  url
openurl 
  Title Influence of temperature of incubation and type of growth medium on pigmentation in Serratia marcescens Type Journal Article
  Year 1971 Publication Journal of Bacteriology Abbreviated Journal J Bacteriol  
  Volume 106 Issue 2 Pages (down) 438-443  
  Keywords Anti-Bacterial Agents/*biosynthesis; Bacterial Proteins/biosynthesis; Bacteriological Techniques; Caseins; Cell Division; Chloramphenicol/pharmacology; *Culture Media; Hot Temperature; Hydrogen-Ion Concentration; Oxygen; Pigments, Biological/*biosynthesis; Prodigiosin/biosynthesis; Protein Hydrolysates; Pyrroles/*biosynthesis; Saccharomyces; Serratia marcescens/cytology/drug effects/growth & development/*metabolism; Spectrophotometry; *Temperature; Time Factors  
  Abstract Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 mug/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.  
  Call Number Serial 1615  
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