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Environmental Microbiology Aug 2019Dickeya dadantii is a plant pathogen that causes soft rot disease on vegetable and potato crops. To successfully cause infection, this pathogen needs to coordinately...
Dickeya dadantii is a plant pathogen that causes soft rot disease on vegetable and potato crops. To successfully cause infection, this pathogen needs to coordinately modulate the expression of genes encoding several virulence determinants, including plant cell wall degrading enzymes (PCWDEs), type III secretion system (T3SS) and flagellar motility. Here, we uncover a novel feed-forward signalling circuit for controlling virulence. Global RNA chaperone Hfq interacts with an Hfq-dependent sRNA ArcZ and represses the translation of pecT, encoding a LysR-type transcriptional regulator. We demonstrate that the ability of ArcZ to be processed to a 50 nt 3'- end fragment is essential for its regulation of pecT. PecT down-regulates PCWDE and the T3SS by repressing the expression of a global post-transcriptional regulator- (RsmA-) associated sRNA encoding gene rsmB. In addition, we show that the protein levels of two cyclic di-GMP (c-di-GMP) diguanylate cyclases (DGCs), GcpA and GcpL, are repressed by Hfq. Further studies show that both DGCs are essential for the Hfq-mediated post-transcriptional regulation on RsmB. Overall, our report provides new insights into the interplays between ubiquitous signalling transduction systems that were most studied independently and sheds light on multitiered regulatory mechanisms for a precise disease regulation in bacteria.
Topics: Bacterial Proteins; Cell Wall; Cyclic GMP; Enterobacteriaceae; Gene Expression Regulation, Bacterial; Plant Diseases; RNA, Bacterial; RNA, Small Untranslated; RNA-Binding Proteins; Signal Transduction; Type III Secretion Systems; Virulence; Virulence Factors
PubMed: 30895662
DOI: 10.1111/1462-2920.14603 -
ACS Chemical Biology Oct 2019Quaternary distance restraints are essential to define the three-dimensional structures of protein assemblies. These distances often fall within a range of 10-18 Å,...
Quaternary distance restraints are essential to define the three-dimensional structures of protein assemblies. These distances often fall within a range of 10-18 Å, which challenges the high and low measurement limits of conventional nuclear magnetic resonance (NMR) and double electron-electron resonance electron spin resonance spectroscopies. Here, we report the use of F paramagnetic relaxation enhancement (PRE) NMR in combination with F/paramagnetic labeling to equivalent sites in different subunits of a protein complex in micelles to determine intersubunit distances. The feasibility of this strategy was evaluated on a pentameric ligand-gated ion channel, for which we found excellent agreement of the F PRE NMR results with previous structural information. The study suggests that F PRE NMR is a viable tool in extracting distance restraints to define quaternary structures.
Topics: Animals; Bacterial Proteins; Dickeya; Fluorine; Gammaproteobacteria; Ion Channels; Mice; Nuclear Magnetic Resonance, Biomolecular; Protein Structure, Quaternary; Protein Subunits
PubMed: 31525026
DOI: 10.1021/acschembio.9b00692 -
International Journal of Biological... Dec 2023Asparaginase has been traditionally applied for only treating acute lymphoblastic leukemia due to its ability to deplete asparagine. However, its ultimate anticancer...
Asparaginase has been traditionally applied for only treating acute lymphoblastic leukemia due to its ability to deplete asparagine. However, its ultimate anticancer potential for treating solid tumors has not yet been unleashed. In this study, we bioengineered Erwinia chrysanthemi asparaginase (ErWT), one of the US Food and Drug Administration-approved types of amino acid depleting enzymes, to achieve double amino acid depletions for treating a solid tumor. We constructed a fusion protein by joining an albumin binding domain (ABD) to ErWT via a linker (GGGGS) to achieve ABD-ErS5. The ABD could bind to serum albumin to form an albumin-ABD-ErS5 complex, which could avoid renal clearance and escape from anti-drug antibodies, resulting in a remarkably prolonged elimination half-life of ABD-ErS5. Meanwhile, ABD-ErS5 did not only deplete asparagine but also glutamine for ∼2 weeks. A biweekly administration of ABD-ErS5 (1.5 mg/kg) significantly suppressed tumor growth in an MKN-45 gastric cancer xenograft model, demonstrating a novel approach for treating solid tumor depleting asparagine and glutamine. Multiple administrations of ABD-ErS5 did not cause any noticeable histopathological abnormalities of key organs, suggesting the absence of acute toxicity to mice. Our results suggest ABD-ErS5 is a potential therapeutic candidate for treating gastric cancer.
Topics: Humans; Animals; Mice; Asparaginase; Antineoplastic Agents; Dickeya chrysanthemi; Asparagine; Glutamine; Stomach Neoplasms; Enterobacteriaceae; Serum Albumin
PubMed: 37923039
DOI: 10.1016/j.ijbiomac.2023.127742