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  • 1
    Publication Date: 2018-05-26
    Description: Tetracyclines have been one of the most successful classes of antibiotics. However, its extensive use has led to the emergence of widespread drug resistance, resulting in discontinuation of use against several bacterial infections. Prominent resistance mechanisms include drug efflux and the use of ribosome protection proteins. Infrequently, tetracyclines can be inactivated by the TetX class of enzymes, also referred to as tetracycline destructases. Low levels of tolerance to tetracycline in Mycobacterium smegmatis and Mycobacterium tuberculosis have been previously attributed to the WhiB7-dependent TetV/Tap efflux pump. However, Mycobacterium abscessus is ~500-fold more resistant to tetracycline than M. smegmatis and M. tuberculosis . In this report, we show that this high level of resistance to tetracycline and doxycycline in M. abscessus is conferred by a WhiB7-independent tetracycline-inactivating monooxygenase, MabTetX (MAB_1496c). The presence of sublethal doses of tetracycline and doxycycline results in a 〉200-fold induction of MabTetX, and an isogenic deletion strain is highly sensitive to both antibiotics. Further, purified MabTetX can rapidly monooxygenate both antibiotics. We also demonstrate that expression of MabTetX is repressed by MabTetR x , by binding to an inverted repeat sequence upstream of MabTetR x ; the presence of either antibiotic relieves this repression. Moreover, anhydrotetracycline (ATc) can effectively inhibit MabTetX activity in vitro and decreases the MICs of both tetracycline and doxycycline in vivo . Finally, we show that tigecycline, a glycylcycline tetracycline, not only is a poor substrate of MabTetX but also is incapable of inducing the expression of MabTetX. This is therefore the first demonstration of a tetracycline-inactivating enzyme in mycobacteria. It (i) elucidates the mechanism of tetracycline resistance in M. abscessus , (ii) demonstrates the use of an inhibitor that can potentially reclaim the use of tetracycline and doxycycline, and (iii) identifies two sequential bottlenecks—MabTetX and MabTetR x —for acquiring resistance to tigecycline, thereby reiterating its use against M. abscessus .
    Print ISSN: 0066-4804
    Electronic ISSN: 1098-6596
    Topics: Biology , Medicine
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  • 2
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2018-11-07
    Description: Halving of the genome during meiosis I is achieved as the homologous chromosomes move to the opposite spindle poles whereas the sister chromatids stay together and move to the same pole. This requires that the sister kinetochores should take a side-by-side orientation in order to connect to the microtubules emanating from the same pole. Factors that constrain sister kinetochores to adopt such orientation are therefore crucial to achieve reductional chromosome segregation in meiosis I. In budding yeast, a protein complex, known as monopolin, is involved in conjoining of the sister kinetochores and thus facilitates their binding to the microtubules from the same pole. In this study, we report Zip1 , a synaptonemal complex component, as another factor that might help the sister kinetochores to take the side-by-side orientation and promote their mono-orientation on the meiosis I spindle. From our results, we propose that the localization of Zip1 at the centromere may provide an additional constraining factor that promotes monopolin to cross-link the sister kinetochores enabling them to mono-orient.
    Electronic ISSN: 2160-1836
    Topics: Biology
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  • 5
    Publication Date: 2011-04-09
    Description: M1 protein, a major virulence factor of the leading invasive strain of group A Streptococcus, is sufficient to induce toxic-shock-like vascular leakage and tissue injury. These events are triggered by the formation of a complex between M1 and fibrinogen that, unlike M1 or fibrinogen alone, leads to neutrophil activation. Here we provide a structural explanation for the pathological properties of the complex formed between streptococcal M1 and human fibrinogen. A conformationally dynamic coiled-coil dimer of M1 was found to organize four fibrinogen molecules into a specific cross-like pattern. This pattern supported the construction of a supramolecular network that was required for neutrophil activation but was distinct from a fibrin clot. Disruption of this network into other supramolecular assemblies was not tolerated. These results have bearing on the pathophysiology of streptococcal toxic shock.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3268815/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3268815/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Macheboeuf, Pauline -- Buffalo, Cosmo -- Fu, Chi-yu -- Zinkernagel, Annelies S -- Cole, Jason N -- Johnson, John E -- Nizet, Victor -- Ghosh, Partho -- R01 AI052453/AI/NIAID NIH HHS/ -- R01 AI052453-10/AI/NIAID NIH HHS/ -- R01 AI077780/AI/NIAID NIH HHS/ -- R01 AI077780-03/AI/NIAID NIH HHS/ -- R01 GM54076/GM/NIGMS NIH HHS/ -- R21 AI071167/AI/NIAID NIH HHS/ -- T32 GM007240/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Apr 7;472(7341):64-8. doi: 10.1038/nature09967.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21475196" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacterial Proteins/chemistry/*metabolism/ultrastructure ; Binding Sites ; Crystallography, X-Ray ; Fibrinogen/*chemistry/metabolism/ultrastructure ; Humans ; Models, Molecular ; Neutrophil Activation ; Protein Binding ; Protein Conformation ; Shock, Septic/microbiology/physiopathology ; Streptococcus pyogenes/chemistry/*pathogenicity ; Virulence ; Virulence Factors/chemistry/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2011-05-03
    Description: How the directionality of vesicle traffic is achieved remains an important unanswered question in cell biology. The Sec23p/Sec24p coat complex sorts the fusion machinery (SNAREs) into vesicles as they bud from the endoplasmic reticulum (ER). Vesicle tethering to the Golgi begins when the tethering factor TRAPPI binds to Sec23p. Where the coat is released and how this event relates to membrane fusion is unknown. Here we use a yeast transport assay to demonstrate that an ER-derived vesicle retains its coat until it reaches the Golgi. A Golgi-associated kinase, Hrr25p (CK1delta orthologue), then phosphorylates the Sec23p/Sec24p complex. Coat phosphorylation and dephosphorylation are needed for vesicle fusion and budding, respectively. Additionally, we show that Sec23p interacts in a sequential manner with different binding partners, including TRAPPI and Hrr25p, to ensure the directionality of ER-Golgi traffic and prevent the back-fusion of a COPII vesicle with the ER. These events are conserved in mammalian cells.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093450/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093450/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lord, Christopher -- Bhandari, Deepali -- Menon, Shekar -- Ghassemian, Majid -- Nycz, Deborah -- Hay, Jesse -- Ghosh, Pradipta -- Ferro-Novick, Susan -- GM-059378/GM/NIGMS NIH HHS/ -- RR-015583/RR/NCRR NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2011 May 12;473(7346):181-6. doi: 10.1038/nature09969. Epub 2011 May 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California at San Diego, La Jolla, California 92093-0668, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21532587" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; COP-Coated Vesicles/metabolism ; Casein Kinase I/*metabolism ; Endoplasmic Reticulum/metabolism ; Golgi Apparatus/*metabolism ; Rats ; SNARE Proteins/metabolism ; Saccharomyces cerevisiae/*metabolism ; Saccharomyces cerevisiae Proteins/metabolism ; Vesicular Transport Proteins/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2012-05-25
    Description: Melanoma is notable for its metastatic propensity, lethality in the advanced setting and association with ultraviolet exposure early in life. To obtain a comprehensive genomic view of melanoma in humans, we sequenced the genomes of 25 metastatic melanomas and matched germline DNA. A wide range of point mutation rates was observed: lowest in melanomas whose primaries arose on non-ultraviolet-exposed hairless skin of the extremities (3 and 14 per megabase (Mb) of genome), intermediate in those originating from hair-bearing skin of the trunk (5-55 per Mb), and highest in a patient with a documented history of chronic sun exposure (111 per Mb). Analysis of whole-genome sequence data identified PREX2 (phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 2)--a PTEN-interacting protein and negative regulator of PTEN in breast cancer--as a significantly mutated gene with a mutation frequency of approximately 14% in an independent extension cohort of 107 human melanomas. PREX2 mutations are biologically relevant, as ectopic expression of mutant PREX2 accelerated tumour formation of immortalized human melanocytes in vivo. Thus, whole-genome sequencing of human melanoma tumours revealed genomic evidence of ultraviolet pathogenesis and discovered a new recurrently mutated gene in melanoma.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367798/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367798/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Berger, Michael F -- Hodis, Eran -- Heffernan, Timothy P -- Deribe, Yonathan Lissanu -- Lawrence, Michael S -- Protopopov, Alexei -- Ivanova, Elena -- Watson, Ian R -- Nickerson, Elizabeth -- Ghosh, Papia -- Zhang, Hailei -- Zeid, Rhamy -- Ren, Xiaojia -- Cibulskis, Kristian -- Sivachenko, Andrey Y -- Wagle, Nikhil -- Sucker, Antje -- Sougnez, Carrie -- Onofrio, Robert -- Ambrogio, Lauren -- Auclair, Daniel -- Fennell, Timothy -- Carter, Scott L -- Drier, Yotam -- Stojanov, Petar -- Singer, Meredith A -- Voet, Douglas -- Jing, Rui -- Saksena, Gordon -- Barretina, Jordi -- Ramos, Alex H -- Pugh, Trevor J -- Stransky, Nicolas -- Parkin, Melissa -- Winckler, Wendy -- Mahan, Scott -- Ardlie, Kristin -- Baldwin, Jennifer -- Wargo, Jennifer -- Schadendorf, Dirk -- Meyerson, Matthew -- Gabriel, Stacey B -- Golub, Todd R -- Wagner, Stephan N -- Lander, Eric S -- Getz, Gad -- Chin, Lynda -- Garraway, Levi A -- DP2 OD002750/OD/NIH HHS/ -- DP2 OD002750-01/OD/NIH HHS/ -- R33 CA126674/CA/NCI NIH HHS/ -- R33 CA126674-03/CA/NCI NIH HHS/ -- R33 CA126674-04/CA/NCI NIH HHS/ -- R33 CA155554/CA/NCI NIH HHS/ -- R33 CA155554-01/CA/NCI NIH HHS/ -- T32 CA009172/CA/NCI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 May 9;485(7399):502-6. doi: 10.1038/nature11071.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22622578" target="_blank"〉PubMed〈/a〉
    Keywords: Chromosome Breakpoints/radiation effects ; DNA Damage ; DNA Mutational Analysis ; Gene Expression Regulation, Neoplastic ; Genome, Human/*genetics ; Guanine Nucleotide Exchange Factors/*genetics/metabolism ; Humans ; Melanocytes/metabolism/pathology ; Melanoma/*genetics/pathology ; Mutagenesis/radiation effects ; Mutation/*genetics/radiation effects ; Oncogenes/genetics ; Sunlight/*adverse effects ; Ultraviolet Rays/adverse effects
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    ISSN: 0167-4838
    Keywords: Lysine metabolism ; Peroxisome defect ; Pipecolic acid metabolism ; Zellweger syndrome ; l-α-Aminoadipate δ-semialdehyde oxidoreductase ; l-α-Aminoadipic acid
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0304-4165
    Keywords: (Intervertebral disc) ; Chondroitin sulfate ; Keratan sulfate ; Proteoglycan
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0304-4165
    Keywords: (Canine intervertebral disc) ; Aging ; Proteoglycan
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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