scholarly journals Structural Basis for Substrate Specificity in ArnB. A Key Enzyme in the Polymyxin Resistance Pathway of Gram-Negative Bacteria

Biochemistry ◽  
2014 ◽  
Vol 53 (4) ◽  
pp. 796-805 ◽  
Author(s):  
Myeongseon Lee ◽  
Marcelo C. Sousa
Keyword(s):  
Substrate Specificity ◽  
Structural Basis ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Resistance Pathway ◽  
Key Enzyme

Structural basis for the recognition of lysozyme by MliC, a periplasmic lysozyme inhibitor in Gram-negative bacteria

2009 ◽  
Vol 378 (2) ◽  
pp. 244-248 ◽  
Author(s):  
Soohwan Yum ◽  
Moon Jong Kim ◽  
Yongbin Xu ◽  
Xiao Ling Jin ◽  
Hee Young Yoo ◽  
...  
Keyword(s):  
Structural Basis ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Lysozyme Inhibitor

scholarly journals Identification of Bdellovibrio bacteriovorus HD100 Bd0714 as a Nudix dGTPase

2008 ◽  
Vol 190 (24) ◽  
pp. 8215-8219 ◽  
Author(s):  
Susan R. Steyert ◽  
Simon A. J. Messing ◽  
L. Mario Amzel ◽  
Sandra B. Gabelli ◽  
Silvia A. Piñeiro
Keyword(s):  
Escherichia Coli ◽  
Life Cycle ◽  
Substrate Specificity ◽  
Gram Negative Bacteria ◽  
Bdellovibrio Bacteriovorus ◽  
Gram Negative ◽  
E Coli

ABSTRACT Bdellovibrio bacteriovorus bacteria are predatory organisms that attack other gram-negative bacteria. Here, we report that Bd0714 is a Nudix dGTPase from B. bacteriovorus HD100 with a substrate specificity similar to that of Escherichia coli MutT and complements an E. coli mutT-deficient strain. We observed different transcription levels of the gene throughout the predator life cycle.

scholarly journals Antimicrobial Peptide Conformation as a Structural Determinant of Omptin Protease Specificity

2015 ◽  
Vol 197 (22) ◽  
pp. 3583-3591 ◽  
Author(s):  
John R. Brannon ◽  
Jenny-Lee Thomassin ◽  
Samantha Gruenheid ◽  
Hervé Le Moual
Keyword(s):  
Substrate Specificity ◽  
Antimicrobial Peptide ◽  
Outer Membrane ◽  
Active Sites ◽  
Catalytic Mechanism ◽  
Structural Basis ◽  
Gram Negative ◽  
Content Type ◽  
Substrate Specificities ◽  
Structural Determinant

ABSTRACTBacterial proteases contribute to virulence by cleaving host or bacterial proteins to promote survival and dissemination. Omptins are a family of proteases embedded in the outer membrane of Gram-negative bacteria that cleave various substrates, including host antimicrobial peptides, with a preference for cleaving at dibasic motifs. OmpT, the enterohemorrhagicEscherichia coli(EHEC) omptin, cleaves and inactivates the human cathelicidin LL-37. Similarly, the omptin CroP, found in the murine pathogenCitrobacter rodentium, which is used as a surrogate model to study human-restricted EHEC, cleaves the murine cathelicidin-related antimicrobial peptide (CRAMP). Here, we compared the abilities of OmpT and CroP to cleave LL-37 and CRAMP. EHEC OmpT degraded LL-37 and CRAMP at similar rates. In contrast,C. rodentiumCroP cleaved CRAMP more rapidly than LL-37. The different cleavage rates of LL-37 and CRAMP were independent of the bacterial background and substrate sequence specificity, as OmpT and CroP have the same preference for cleaving at dibasic sites. Importantly, LL-37 was α-helical and CRAMP was unstructured under our experimental conditions. By altering the α-helicity of LL-37 and CRAMP, we found that decreasing LL-37 α-helicity increased its rate of cleavage by CroP. Conversely, increasing CRAMP α-helicity decreased its cleavage rate. This structural basis for CroP substrate specificity highlights differences between the closely related omptins ofC. rodentiumandE. coli. In agreement with previous studies, this difference in CroP and OmpT substrate specificity suggests that omptins evolved in response to the substrates present in their host microenvironments.IMPORTANCEOmptins are recognized as key virulence factors for various Gram-negative pathogens. Their localization to the outer membrane, their active site facing the extracellular environment, and their unique catalytic mechanism make them attractive targets for novel therapeutic strategies. Gaining insights into similarities and variations between the different omptin active sites and subsequent substrate specificities will be critical to develop inhibitors that can target multiple omptins. Here, we describe subtle differences between the substrate specificities of two closely related omptins, CroP and OmpT. This is the first reported example of substrate conformation acting as a structural determinant for omptin activity between OmpT-like proteases.

scholarly journals Structural Basis of a Temporin 1b Analogue Antimicrobial Activity against Gram Negative Bacteria Determined by CD and NMR Techniques in Cellular Environment

2015 ◽  
Vol 10 (4) ◽  
pp. 965-969 ◽  
Author(s):  
Gaetano Malgieri ◽  
Concetta Avitabile ◽  
Maddalena Palmieri ◽  
Luca Domenico D’Andrea ◽  
Carla Isernia ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Structural Basis ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Cellular Environment ◽  
Nmr Techniques

scholarly journals Gram-Negative Bacteria Salmonella typhimurium Boost Leukotriene Synthesis Induced by Chemoattractant fMLP to Stimulate Neutrophil Swarming

2022 ◽  
Vol 12 ◽  
Author(s):  
Ekaterina A. Golenkina ◽  
Svetlana I. Galkina ◽  
Olga Pletjushkina ◽  
Boris Chernyak ◽  
Tatjana V. Gaponova ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Nuclear Membrane ◽  
Crucial Role ◽  
Bacterial Lipopolysaccharide ◽  
Human Neutrophils ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Reverse Sequence ◽  
Key Enzyme

Leukotriene synthesis in neutrophils is critical for host survival during infection. In particular, leukotriene B4 (LTB4) is a powerful neutrophil chemoattractant that plays a crucial role in neutrophil swarming. In this work, we demonstrated that preincubation of human neutrophils with Salmonella typhimurium strongly stimulated LTB4 production induced by the bacterial chemoattractant, peptide N-formyl-L-methionyl-L-leucyl-l-phenylalanine (fMLP), while the reverse sequence of additions was ineffective. Preincubation with bacterial lipopolysaccharide or yeast polysaccharide zymosan particles gives weaker effect on fMLP-induced LTB4 production. Activation of 5-lipoxygenase (5-LOX), a key enzyme in leukotrienes biosynthesis, depends on rise of cytosolic concentration of Ca2+ and on translocation of the enzyme to the nuclear membrane. Both processes were stimulated by S. typhimurium. With an increase in the bacteria:neutrophil ratio, the transformation of LTB4 to ω-OH-LTB4 was suppressed, which further supported increased concentration of LTB4. These data indicate that in neutrophils gathered around bacterial clusters, LTB4 production is stimulated and at the same time its transformation is suppressed, which promotes neutrophil swarming and elimination of pathogens simultaneously.

What is the substrate specificity of the System I cytochrome c biogenesis apparatus?

2006 ◽  
Vol 34 (1) ◽  
pp. 150-151 ◽  
Author(s):  
J.W.A. Allen ◽  
S.J. Ferguson
Keyword(s):  
Cytochrome C ◽  
Substrate Specificity ◽  
Nitrogen Cycle ◽  
Covalent Attachment ◽  
Binding Motif ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Cytochrome C Maturation ◽  
Cytochrome C Biogenesis

c-Type cytochromes are characterized by covalent attachment of haem to protein through thioether bonds between the vinyl groups of the haem and the thiols of a CXXCH motif. Proteins of this type play crucial roles in the biochemistry of the nitrogen cycle. Many Gram-negative bacteria use the Ccm (cytochrome c maturation) proteins for the post-translational haem attachment to their c-type cytochromes; in the present paper, we discuss the substrate specificity of the Ccm apparatus. The main conclusion is that the feature recognized and required in the apocytochrome is simply the two cysteines and the histidine of the haem-binding motif.

scholarly journals Structural basis of cell-surface signaling by a conserved sigma regulator in Gram-negative bacteria

2020 ◽  
Vol 295 (17) ◽  
pp. 5795-5806 ◽  
Author(s):  
Jaime L. Jensen ◽  
Beau D. Jernberg ◽  
Sangita C. Sinha ◽  
Christopher L. Colbert
Keyword(s):  
Cell Surface ◽  
Conformational Changes ◽  
Cd Spectroscopy ◽  
Structural Basis ◽  
Titration Calorimetry ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Regulatory Pathways ◽  
Surface Signaling ◽  
Cell Surface Signaling

Cell-surface signaling (CSS) in Gram-negative bacteria involves highly conserved regulatory pathways that optimize gene expression by transducing extracellular environmental signals to the cytoplasm via inner-membrane sigma regulators. The molecular details of ferric siderophore-mediated activation of the iron import machinery through a sigma regulator are unclear. Here, we present the 1.56 Å resolution structure of the periplasmic complex of the C-terminal CSS domain (CCSSD) of PupR, the sigma regulator in the Pseudomonas capeferrum pseudobactin BN7/8 transport system, and the N-terminal signaling domain (NTSD) of PupB, an outer-membrane TonB-dependent transducer. The structure revealed that the CCSSD consists of two subdomains: a juxta-membrane subdomain, which has a novel all-β-fold, followed by a secretin/TonB, short N-terminal subdomain at the C terminus of the CCSSD, a previously unobserved topological arrangement of this domain. Using affinity pulldown assays, isothermal titration calorimetry, and thermal denaturation CD spectroscopy, we show that both subdomains are required for binding the NTSD with micromolar affinity and that NTSD binding improves CCSSD stability. Our findings prompt us to present a revised model of CSS wherein the CCSSD:NTSD complex forms prior to ferric-siderophore binding. Upon siderophore binding, conformational changes in the CCSSD enable regulated intramembrane proteolysis of the sigma regulator, ultimately resulting in transcriptional regulation.

scholarly journals Structural Basis for the Lipopolysaccharide Export Activity of the Bacterial Lipopolysaccharide Transport System

2018 ◽  
Vol 19 (9) ◽  
pp. 2680 ◽  
Author(s):  
Greg Hicks ◽  
Zongchao Jia
Keyword(s):  
Protein Complex ◽  
Structural Basis ◽  
Gram Negative Bacteria ◽  
The Novel ◽  
Membrane Stress ◽  
Gram Negative ◽  
Export Activity ◽  
System A ◽  
Continuous Stream ◽  
Dependent Mechanism

Gram-negative bacteria have a dense outer membrane (OM) coating of lipopolysaccharides, which is essential to their survival. This coating is assembled by the LPS (lipopolysaccharide) transport (Lpt) system, a coordinated seven-subunit protein complex that spans the cellular envelope. LPS transport is driven by an ATPase-dependent mechanism dubbed the “PEZ” model, whereby a continuous stream of LPS molecules is pushed from subunit to subunit. This review explores recent structural and functional findings that have elucidated the subunit-scale mechanisms of LPS transport, including the novel ABC-like mechanism of the LptB2FG subcomplex and the lateral insertion of LPS into the OM by LptD/E. New questions are also raised about the functional significance of LptA oligomerization and LptC. The tightly regulated interactions between these connected subcomplexes suggest a pathway that can react dynamically to membrane stress and may prove to be a valuable target for new antibiotic therapies for Gram-negative pathogens.

Structural Basis of Sequential Allosteric Transitions in Tetramericd-Lactate Dehydrogenases from Three Gram-Negative Bacteria

Biochemistry ◽  
2018 ◽  
Vol 57 (37) ◽  
pp. 5388-5406
Author(s):  
Nayuta Furukawa ◽  
Akimasa Miyanaga ◽  
Masahiro Nakajima ◽  
Hayao Taguchi
Keyword(s):  
Structural Basis ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Allosteric Transitions ◽  
Lactate Dehydrogenases
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