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  1. Article: Helicobacter pylori does not use spermidine synthase to produce spermidine

    Zhang, Huawei / Shannon Wing Ngor Au

    Biochemical and biophysical research communications. 2017,

    2017  

    Abstract: Helicobacter pylori is the primary pathogen associated to gastritis and gastric cancer. Growth of H. pylori depends on the availability of spermidine in vivo. Interestingly, the genome of H. pylori contains an incomplete set of genes for the classical ... ...

    Abstract Helicobacter pylori is the primary pathogen associated to gastritis and gastric cancer. Growth of H. pylori depends on the availability of spermidine in vivo. Interestingly, the genome of H. pylori contains an incomplete set of genes for the classical pathway of spermidine biosynthesis. It is thus not clear whether some other genes remained in the pathway would have any functions in spermidine biosynthesis. Here, we study spermidine synthase, which is responsible for the final catalytic process in the classical route. Protein sequence alignment reveals that H. pylori SpeE (HpSpeE) lacks key residues for substrate binding. By using isothermal titration calorimetry, we show that purified recombinant HpSpeE does not interact with the putative substrates putrescine and decarboxylated S-adenosylmethionine, and the product spermidine. High performance liquid chromatography analysis further demonstrates that HpSpeE has no detectable in vitro enzymatic activity. Additionally, intracellular spermidine level in speE-null mutant strain is comparable to that in the wild type strain. Collectively, our results suggest that HpSpeE is functionally distinct from spermidine production. H. pylori may instead employ the alternative pathway for spermidine synthesis which is dominantly exploited by other human gut microbes.
    Keywords Helicobacter pylori ; S-adenosylmethionine ; biosynthesis ; calorimetry ; enzyme activity ; gastritis ; genes ; high performance liquid chromatography ; humans ; intestinal microorganisms ; mutants ; pathogens ; putrescine ; sequence alignment ; spermidine ; spermidine synthase ; stomach neoplasms ; titration
    Language English
    Size p. .
    Publishing place Elsevier Inc.
    Document type Article
    Note Pre-press version
    ZDB-ID 205723-2
    ISSN 0006-291X ; 0006-291X
    ISSN (online) 0006-291X
    ISSN 0006-291X
    DOI 10.1016/j.bbrc.2017.06.132
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Cryo-EM structures of ClC-2 chloride channel reveal the blocking mechanism of its specific inhibitor AK-42

    Tao Ma / Lei Wang / Anping Chai / Chao Liu / Wenqiang Cui / Shuguang Yuan / Shannon Wing Ngor Au / Liang Sun / Xiaokang Zhang / Zhenzhen Zhang / Jianping Lu / Yuanzhu Gao / Peiyi Wang / Zhifang Li / Yujie Liang / Horst Vogel / Yu Tian Wang / Daping Wang / Kaige Yan /
    Huawei Zhang

    Nature Communications, Vol 14, Iss 1, Pp 1-

    2023  Volume 13

    Abstract: Abstract ClC-2 transports chloride ions across plasma membranes and plays critical roles in cellular homeostasis. Its dysfunction is involved in diseases including leukodystrophy and primary aldosteronism. AK-42 was recently reported as a specific ... ...

    Abstract Abstract ClC-2 transports chloride ions across plasma membranes and plays critical roles in cellular homeostasis. Its dysfunction is involved in diseases including leukodystrophy and primary aldosteronism. AK-42 was recently reported as a specific inhibitor of ClC-2. However, experimental structures are still missing to decipher its inhibition mechanism. Here, we present cryo-EM structures of apo ClC-2 and its complex with AK-42, both at 3.5 Å resolution. Residues S162, E205 and Y553 are involved in chloride binding and contribute to the ion selectivity. The side-chain of the gating glutamate E205 occupies the putative central chloride-binding site, indicating that our structure represents a closed state. Structural analysis, molecular dynamics and electrophysiological recordings identify key residues to interact with AK-42. Several AK-42 interacting residues are present in ClC-2 but not in other ClCs, providing a possible explanation for AK-42 specificity. Taken together, our results experimentally reveal the potential inhibition mechanism of ClC-2 inhibitor AK-42.
    Keywords Science ; Q
    Subject code 572 ; 540
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Degradation of nuclear Ubc9 induced by listeriolysin O is dependent on K+ efflux

    Li, Jiexin / Shannon Wing-ngor Au / Tsz-wah Lai / Wendy Wai-ling Lam

    Biochemical and biophysical research communications. 2017,

    2017  

    Abstract: Listeriolysin O (LLO) is a pore-forming toxin produced by L. monocytogenes, and is belonged to a protein family of cholesterol-dependent cytolysins (CDCs). Previous studies have demonstrated that LLO triggers Ubc9 degradation and disrupts host ... ...

    Abstract Listeriolysin O (LLO) is a pore-forming toxin produced by L. monocytogenes, and is belonged to a protein family of cholesterol-dependent cytolysins (CDCs). Previous studies have demonstrated that LLO triggers Ubc9 degradation and disrupts host SUMOylation to facilitate bacterial infection. However, the underlying mechanism of Ubc9 degradation is unclear. Here we show that LLO-induced down-regulation of Ubc9 is independent of Ubc9-SUMO interaction, however, it may involve phosphorylation signaling. Additionally, LLO exerts its effects primarily on nuclear Ubc9 and this process is mediated by K+ efflux. Interestingly, for intracellular CDCs such as pneumolysin and suilysin, blockage of K+ efflux enhances degradation of nuclear Ubc9, suggesting that extracellular and intracellular pathogens may exploit different mechanisms to modulate host SUMOylation system. Furthermore, up-regulation of SUMOylation by stable expression of SUMO-1 or SUMO-2 shows a delay in membrane perforation by LLO, indicating that SUMO modification of host proteins may act at the frontline for the defense response against LLO. Taken together, our study provides insights to the understanding of host-pathogen interactions.
    Keywords bacterial infections ; host-pathogen relationships ; pathogens ; phosphorylation ; pneumolysin ; potassium ; proteins
    Language English
    Size p. .
    Publishing place Elsevier Inc.
    Document type Article
    Note Pre-press version
    ZDB-ID 205723-2
    ISSN 0006-291X ; 0006-291X
    ISSN (online) 0006-291X
    ISSN 0006-291X
    DOI 10.1016/j.bbrc.2017.09.051
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 71/706: Show issues
    Z 3.8: Show issues

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  4. Article ; Online: Modular enzyme assembly for enhanced cascade biocatalysis and metabolic flux

    Wei Kang / Tian Ma / Min Liu / Jiale Qu / Zhenjun Liu / Huawei Zhang / Bin Shi / Shuai Fu / Juncai Ma / Louis Tung Faat Lai / Sicong He / Jianan Qu / Shannon Wing-Ngor Au / Byung Ho Kang / Wilson Chun Yu Lau / Zixin Deng / Jiang Xia / Tiangang Liu

    Nature Communications, Vol 10, Iss 1, Pp 1-

    2019  Volume 11

    Abstract: Metabolic enzymes often form supramolecular complexes to improve product yield. Here the authors use short peptide tags to create scaffold-free assemblies and synthetic metabolic nodes. ...

    Abstract Metabolic enzymes often form supramolecular complexes to improve product yield. Here the authors use short peptide tags to create scaffold-free assemblies and synthetic metabolic nodes.
    Keywords Science ; Q
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Modular enzyme assembly for enhanced cascade biocatalysis and metabolic flux

    Wei Kang / Tian Ma / Min Liu / Jiale Qu / Zhenjun Liu / Huawei Zhang / Bin Shi / Shuai Fu / Juncai Ma / Louis Tung Faat Lai / Sicong He / Jianan Qu / Shannon Wing-Ngor Au / Byung Ho Kang / Wilson Chun Yu Lau / Zixin Deng / Jiang Xia / Tiangang Liu

    Nature Communications, Vol 10, Iss 1, Pp 1-

    2019  Volume 11

    Abstract: Metabolic enzymes often form supramolecular complexes to improve product yield. Here the authors use short peptide tags to create scaffold-free assemblies and synthetic metabolic nodes. ...

    Abstract Metabolic enzymes often form supramolecular complexes to improve product yield. Here the authors use short peptide tags to create scaffold-free assemblies and synthetic metabolic nodes.
    Keywords Science ; Q
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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  6. Article ; Online: Influenza polymerase activity correlates with the strength of interaction between nucleoprotein and PB2 through the host-specific residue K/E627.

    Andy Ka-Leung Ng / Wai-Hon Chan / Sze-Ting Choi / Mandy Ka-Han Lam / Kwok-Fai Lau / Paul Kay-Sheung Chan / Shannon Wing-Ngor Au / Ervin Fodor / Pang-Chui Shaw

    PLoS ONE, Vol 7, Iss 5, p e

    2012  Volume 36415

    Abstract: The ribonucleoprotein (RNP) complex is the essential transcription-replication machinery of the influenza virus. It is composed of the trimeric polymerase (PA, PB1 and PB2), nucleoprotein (NP) and RNA. Elucidating the molecular mechanisms of RNP assembly ...

    Abstract The ribonucleoprotein (RNP) complex is the essential transcription-replication machinery of the influenza virus. It is composed of the trimeric polymerase (PA, PB1 and PB2), nucleoprotein (NP) and RNA. Elucidating the molecular mechanisms of RNP assembly is central to our understanding of the control of viral transcription and replication and the dependence of these processes on the host cell. In this report, we show, by RNP reconstitution assays and co-immunoprecipitation, that the interaction between NP and polymerase is crucial for the function of the RNP. The functional association of NP and polymerase involves the C-terminal '627' domain of PB2 and it requires NP arginine-150 and either lysine-627 or arginine-630 of PB2. Using surface plasmon resonance, we demonstrate that the interaction between NP and PB2 takes place without the involvement of RNA. At 33, 37 and 41°C in mammalian cells, more positive charges at aa. 627 and 630 of PB2 lead to stronger NP-polymerase interaction, which directly correlates with the higher RNP activity. In conclusion, our study provides new information on the NP-PB2 interaction and shows that the strength of NP-polymerase interaction and the resulting RNP activity are promoted by the positive charges at aa. 627 and 630 of PB2.
    Keywords Medicine ; R ; Science ; Q
    Subject code 570
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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