Michael S Manak

University of Florida, Gainesville, FL, United States

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Publications (15)

  • G.J.P.L. Kops · M. van der Voet · M.S. Manak · [...] · J.V. Shah
    Article · Jan 2015
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    Anna-Lisa Paul · Michael S Manak · John D Mayfield · [...] · Robert J Ferl
    [Show abstract] [Hide abstract] ABSTRACT: Our primary objective was to evaluate gene expression changes in Arabidopsis thaliana in response to parabolic flight as part of a comprehensive approach to the molecular biology of spaceflight-related adaptations. In addition, we wished to establish parabolic flight as a tractable operations platform for molecular biology studies. In a succession of experiments on NASA's KC-135 and C-9 parabolic aircraft, Arabidopsis plants were presented with replicated exposure to parabolic flight. Transcriptome profiling revealed that parabolic flight caused changes in gene expression patterns that stood the statistical tests of replication on three different flight days. The earliest response, after 20 parabolas, was characterized by a prominence of genes associated with signal transduction. After 40 parabolas, this prominence was largely replaced by genes associated with biotic and abiotic stimuli and stress. Among these responses, three metabolic processes stand out in particular: the induction of auxin metabolism and signaling, the differential expression of genes associated with calcium-mediated signaling, and the repression of genes associated with disease resistance and cell wall biochemistry. Many, but not all, of these responses are known to be involved in gravity sensing in plants. Changes in auxin-related gene expression were also recorded by reporter genes tuned to auxin signal pathways. These data demonstrate that the parabolic flight environment is appropriate for molecular biology research involving the transition to microgravity, in that with replication, proper controls, and analyses, gene expression changes can be observed in the time frames of typical parabolic flight experiments.
    Full-text Article · Oct 2011 · Astrobiology
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    Robert S Hagan · Michael S Manak · Håkon Kirkeby Buch · [...] · Peter K Sorger
    [Show abstract] [Hide abstract] ABSTRACT: The spindle assembly checkpoint links the onset of anaphase to completion of chromosome-microtubule attachment and is mediated by the binding of Mad and Bub proteins to kinetochores of unattached or maloriented chromosomes. Mad2 and BubR1 traffic between kinetochores and the cytosol, thereby transmitting a "wait anaphase" signal to the anaphase-promoting complex. It is generally assumed that this signal dissipates automatically upon kinetochore-microtubule binding, but it has been shown that under conditions of nocodazole-induced arrest p31(comet), a Mad2-binding protein, is required for mitotic progression. In this article we investigate the localization and function of p31(comet) during normal, unperturbed mitosis in human and marsupial cells. We find that, like Mad2, p31(comet) traffics on and off kinetochores and is also present in the cytosol. Cells depleted of p31(comet) arrest in metaphase with mature bipolar kinetochore-microtubule attachments, a satisfied checkpoint, and high cyclin B levels. Thus p31(comet) is required for timely mitotic exit. We propose that p31(comet) is an essential component of the machinery that silences the checkpoint during each cell cycle.
    Full-text Article · Sep 2011 · Molecular biology of the cell
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    G. J. P. L. Kops · M. van der Voet · M. S. Manak · [...] · J. V. Shah
    Full-text Article · May 2010 · Journal of Cell Science
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    Nicholas Kwiatkowski · Nannette Jelluma · Panagis Filippakopoulos · [...] · Nathanael S Gray
    [Show abstract] [Hide abstract] ABSTRACT: Mps1, a dual-specificity kinase, is required for the proper functioning of the spindle assembly checkpoint and for the maintenance of chromosomal stability. As Mps1 function has been implicated in numerous phases of the cell cycle, the development of a potent, selective small-molecule inhibitor of Mps1 should facilitate dissection of Mps1-related biology. We describe the cellular effects and Mps1 cocrystal structures of new, selective small-molecule inhibitors of Mps1. Consistent with RNAi studies, chemical inhibition of Mps1 leads to defects in Mad1 and Mad2 establishment at unattached kinetochores, decreased Aurora B kinase activity, premature mitotic exit and gross aneuploidy, without any evidence of centrosome duplication defects. However, in U2OS cells having extra centrosomes (an abnormality found in some cancers), Mps1 inhibition increases the frequency of multipolar mitoses. Lastly, Mps1 inhibitor treatment resulted in a decrease in cancer cell viability.
    Full-text Article · Apr 2010 · Nature Chemical Biology
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    [Show abstract] [Hide abstract] ABSTRACT: Error-free chromosome segregation depends on timely activation of the multi-subunit E3 ubiquitin ligase APC/C. Activation of the APC/C initiates chromosome segregation and mitotic exit by targeting critical cell-cycle regulators for destruction. The APC/C is the principle target of the mitotic checkpoint, which prevents segregation while chromosomes are unattached to spindle microtubules. We now report the identification and characterization of APC16, a conserved subunit of the APC/C. APC16 was found in association with tandem-affinity-purified mitotic checkpoint complex protein complexes. APC16 is a bona fide subunit of human APC/C: it is present in APC/C complexes throughout the cell cycle, the phenotype of APC16-depleted cells copies depletion of other APC/C subunits, and APC16 is important for APC/C activity towards mitotic substrates. APC16 sequence homologues can be identified in metazoans, but not fungi, by four conserved primary sequence stretches. We provide evidence that the C. elegans gene K10D2.4 and the D. rerio gene zgc:110659 are functional equivalents of human APC16. Our findings show that APC/C is composed of previously undescribed subunits, and raise the question of why metazoan APC/C is molecularly different from unicellular APC/C.
    Full-text Article · Apr 2010 · Journal of Cell Science
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    Nicholas Kwiatkowski · Nannette Jelluma · Panagis Filippakopoulos · [...] · Nathanael S. Gray
    Full-text Dataset · Mar 2010
  • Michael S Manak · Robert J Ferl
    [Show abstract] [Hide abstract] ABSTRACT: Oscillations in cellular divalent cation concentrations are key events that can trigger signal transduction cascades. Common cellular divalent cations, such as calcium and magnesium, interact with 14-3-3 proteins. The metal ion interaction causes a conformational change in the 14-3-3 proteins, which is manifested as an increase in hydrophobicity. In this study, the effect of divalent cations on the interaction between 14-3-3 proteins and target peptides was investigated using surface plasmon resonance and isothermal titration calorimetry. The binding between ten recombinant Arabidopsis 14-3-3 isoforms and two synthetic target peptides was observed in the presence of various physiologically relevant concentrations of calcium or magnesium, from 1 microM to 1 mM or from 1 microM to 5 mM, respectively. The synthetic target peptides were based on sequences from Arabidopsis nitrate reductase (NR2) and the plasma membrane proton pump (AHA2) representing fundamentally different target classes. Isoforms representing every branch of the Arabidopsis 14-3-3 phylogenetic tree were tested. The general result for all cases is that an increased concentration of divalent cations in solution causes an increase in the concentration of 14-3-3 protein interacting with the respective phosphopeptide.
    Article · Feb 2007 · Biochemistry
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    [Show abstract] [Hide abstract] ABSTRACT: As a step in developing an understanding of plant adaptation to low atmospheric pressures, we have identified genes central to the initial response of Arabidopsis to hypobaria. Exposure of plants to an atmosphere of 10 kPa compared with the sea-level pressure of 101 kPa resulted in the significant differential expression of more than 200 genes between the two treatments. Less than one-half of the genes induced by hypobaria are similarly affected by hypoxia, suggesting that response to hypobaria is unique and is more complex than an adaptation to the reduced partial pressure of oxygen inherent to hypobaric environments. In addition, the suites of genes induced by hypobaria confirm that water movement is a paramount issue at low atmospheric pressures, because many of gene products intersect abscisic acid-related, drought-induced pathways. A motivational constituent of these experiments is the need to address the National Aeronautics and Space Administration's plans to include plants as integral components of advanced life support systems. The design of bioregenerative life support systems seeks to maximize productivity within structures engineered to minimize mass and resource consumption. Currently, there are severe limitations to producing Earth-orbital, lunar, or Martian plant growth facilities that contain Earth-normal atmospheric pressures within light, transparent structures. However, some engineering limitations can be offset by growing plants in reduced atmospheric pressures. Characterization of the hypobaric response can therefore provide data to guide systems engineering development for bioregenerative life support, as well as lead to fundamental insights into aspects of desiccation metabolism and the means by which plants monitor water relations.
    Full-text Article · Feb 2004 · Plant physiology
  • Article: The 14-3-3s
    Robert J Ferl · Michael S Manak · Matthew F Reyes
    [Show abstract] [Hide abstract] ABSTRACT: Multiple members of the 14-3-3 protein family have been found in all eukaryotes so far investigated, yet they are apparently absent from prokaryotes. The major native forms of 14-3-3s are homo- and hetero-dimers, the biological functions of which are to interact physically with specific client proteins and thereby effect a change in the client. As a result, 14-3-3s are involved in a vast array of processes such as the response to stress, cell-cycle control, and apoptosis, serving as adapters, activators, and repressors. There are currently 133 full-length sequences available in GenBank for this highly conserved protein family. A phylogenetic tree based on the conserved middle core region of the protein sequences shows that, in plants, the 14-3-3 family can be divided into two clearly defined groups. The core region encodes an amphipathic groove that binds the multitude of client proteins that have conserved 14-3-3-recognition sequences. The amino and carboxyl termini of 14-3-3 proteins are much more divergent than the core region and may interact with isoform-specific client proteins and/or confer specialized subcellular and tissue localization.
    Article · Jul 2002 · Genome biology
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    Michael S Manak · Anna-Lisa Paul · Paul C Sehnke · Robert J Ferl
    [Show abstract] [Hide abstract] ABSTRACT: Transgenic arabidopsis plants containing the alcohol dehydrogenase (Adh) gene promoter fused to the green fluorescent protein (GFP) reporter gene were developed as biological sensors for monitoring physiological responses to unique environments. Plants were monitored in vivo during exposure to hypoxia, high salt, cold, and abcissic acid in experiments designed to characterize the utility and responses of the Adh/GFP biosensors. Plants in the presence of environmental stimuli that induced the Adh promoter responded by expressing GFP, which in turn generated a detectable fluorescent signal. The GFP signal degraded when the inducing stimulus was removed. Digital imaging of the Adh/GFP plants exposed to each of the exogenous stresses demonstrated that the stress-induced gene expression could be followed in real time. The experimental results established the feasibility of using a digital monitoring system for collecting gene expression data in real time from Transgenic Arabidopsis Gene Expression System (TAGES) biosensor plants during space exploration experiments.
    Full-text Article · Feb 2002 · Life support & biosphere science: international journal of earth space
  • Article: The 14-3-3s
    Robert J. Ferl · Michael S. Manak · Matthew F. Reyes
    [Show abstract] [Hide abstract] ABSTRACT: Multiple members of the 14-3-3 protein family have been found in all eukaryotes so far investigated, yet they are apparently absent from prokaryotes. The major native forms of 14-3-3s are homo-and hetero-dimers, the biological functions of which are to interact physically with specific client proteins and thereby effect a change in the client. As a result, 14-3-3s are involved in a vast array of processes such as the response to stress, cell-cycle control, and apoptosis, serving as adapters, activators, and repressors. There are currently 133 full-length sequences available in GenBank for this highly conserved protein family. A phylogenetic tree based on the conserved middle core region of the protein sequences shows that, in plants, the 14-3-3 family can be divided into two clearly defined groups. The core region encodes an amphipathic groove that binds the multitude of client proteins that have conserved 14-3-3-recognition sequences. The amino and carboxyl termini of 14-3-3 proteins are much more divergent than the core region and may interact with isoform-specific client proteins and/or confer specialized subcellular and tissue localization.
    Article · Jan 2002 · Genome biology
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    [Show abstract] [Hide abstract] ABSTRACT: The AM1-calculated partial oxygen charge of several phenoxide anions, potential ligands for tungsten-based classical catalytic systems for olefin metathesis, has been used as an indication of their electronwithdrawing ability. Based on the modeled set, a number of bis(aryloxide) derivatives of tungsten (VI) oxychloride have been synthesized by refluxing the parent phenol and WOCl4 in toluene, and we have explored their ability to catalyze various metathesis applications. The studied complexes are precursors to active metathesis catalysts when heated in the presence of Bu4Sn, and experimental conditions for the catalysis of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) polymerization, and ring closing metathesis (RCM) are reported. The catalytic ability of the studied complexes cannot be predicted based on a single structural or electronic parameter since ligand substitution also seems to affect other features such as solubility and chemical stability of the complex. Crystal data for bis(2,4,6-tribromophenoxy)tungsten (VI) oxychloride (7): Space group: P1, triclinic. a=7.8459(5) Å, α=94.100(1)°, b=8.8504(5) Å, β=92.687(1)°, c=14.2994(9) Å, γ=95.359(1)°, V=984.64(10) Å3, R1=0.0258 and wR2=0.0628.
    Full-text Article · Oct 2000 · Journal of Molecular Catalysis A Chemical
  • Michael S Manak
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  • Michael S Manak
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