scholarly journals Structural mechanism of Staphylococcus aureus Hfq binding to an RNA A-tract

2012 ◽  
Vol 40 (21) ◽  
pp. 11023-11035 ◽  
Author(s):  
Nicola Horstmann ◽  
Jillian Orans ◽  
Poul Valentin-Hansen ◽  
Samuel A. Shelburne ◽  
Richard G. Brennan
Keyword(s):  
Staphylococcus Aureus ◽  
Structural Mechanism

scholarly journals Conformational equilibrium defines the variable induction of the multidrug-binding transcriptional repressor QacR

2019 ◽  
Vol 116 (40) ◽  
pp. 19963-19972 ◽  
Author(s):  
Koh Takeuchi ◽  
Misaki Imai ◽  
Ichio Shimada
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Conformational Equilibrium ◽  
Transcriptional Repressor ◽  
Structural Basis ◽  
Transcriptional Level ◽  
Multidrug Transporter ◽  
Transporter Gene ◽  
Structural Mechanism ◽  
Basal Expression

QacR, a multidrug-binding transcriptional repressor in pathogenic bacteria Staphylococcus aureus, modulates the transcriptional level of the multidrug transporter gene, qacA, in response to engaging a set of diverse ligands. However, the structural basis that defines the variable induction level remains unknown. Here, we reveal that the conformational equilibrium between the repressive and inducive conformations in QacR defines the induction level of the transporter gene. In addition, the unligated QacR is already partly populated in the inducive conformation, allowing the basal expression of the transporter. We also showed that, in the known constitutively active QacR mutants, the equilibrium is shifted more toward the inducive conformation, even in the unligated state. These results highlight the unexpected structural mechanism, connecting the promiscuous multidrug binding to the variable transcriptional regulation of QacR, which provide clues to dysfunctioning of the multidrug resistance systems.

scholarly journals Structural mechanism of transcription regulation of the Staphylococcus aureus multidrug efflux operon mepRA by the MarR family repressor MepR

2013 ◽  
Vol 42 (4) ◽  
pp. 2774-2788 ◽  
Author(s):  
Ivan Birukou ◽  
Susan M. Seo ◽  
Bryan D. Schindler ◽  
Glenn W. Kaatz ◽  
Richard G. Brennan
Keyword(s):  
Staphylococcus Aureus ◽  
Dna Binding ◽  
Conformational Changes ◽  
Efflux Pump ◽  
Binding Activity ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Structural Mechanism ◽  
Dna Binding Activity ◽  
Complex Structural

Abstract The multidrug efflux pump MepA is a major contributor to multidrug resistance in Staphylococcus aureus. MepR, a member of the multiple antibiotic resistance regulator (MarR) family, represses mepA and its own gene. Here, we report the structure of a MepR–mepR operator complex. Structural comparison of DNA-bound MepR with ‘induced’ apoMepR reveals the large conformational changes needed to allow the DNA-binding winged helix-turn-helix motifs to interact with the consecutive major and minor grooves of the GTTAG signature sequence. Intriguingly, MepR makes no hydrogen bonds to major groove nucleobases. Rather, recognition-helix residues Thr60, Gly61, Pro62 and Thr63 make sequence-specifying van der Waals contacts with the TTAG bases. Removing these contacts dramatically affects MepR–DNA binding activity. The wings insert into the flanking minor grooves, whereby residue Arg87, buttressed by Asp85, interacts with the O2 of T4 and O4′ ribosyl oxygens of A23 and T4. Mutating Asp85 and Arg87, both conserved throughout the MarR family, markedly affects MepR repressor activity. The His14′:Arg59 and Arg10′:His35:Phe108 interaction networks stabilize the DNA-binding conformation of MepR thereby contributing significantly to its high affinity binding. A structure-guided model of the MepR–mepA operator complex suggests that MepR dimers do not interact directly and cooperative binding is likely achieved by DNA-mediated allosteric effects.

Cytochemical Studies of Cell Wall Biosynthesis in Staphylococcus Aureus

1972 ◽  
Vol 30 ◽  
pp. 328-329
Author(s):  
Masaatsu Koike ◽  
Koichi Nakashima ◽  
Kyoko Iida
Keyword(s):  
Staphylococcus Aureus ◽  
Periodate Oxidation ◽  
Early Time ◽  
The Other ◽  
Penicillin G ◽  
Cell Wall Biosynthesis ◽  
Septal Wall ◽  
Peptidoglycan Biosynthesis ◽  
Gram Positive Bacteria ◽  
Cross Linkage

Penicillin exerts the activity to inhibit the peptide cross linkage between each polysaccharide backbone at the final stage of wall-peptidoglycan biosynthesis of bacteria. Morphologically, alterations of the septal wall and mesosome in gram-positive bacteria, which were occurred in early time after treatment with penicillin, have been observed. In this experiment, these alterations were cytochemically investigated by means of silver-methenamine staining after periodate oxidation, which is applied for detection of localization of wall mucopolysaccharide.Staphylococcus aureus strain 209P treated with 100 u/ml of penicillin G was divided into two aliquotes. One was fixed by Kellenberger-Ryter's OSO4 fixative at 30, 60 and 120 min after addition of the antibiotic, dehydrated through alcohol series, and embedded in Epon 812 (Specimen A). The other was fixed by 21 glutaraldehyde, dehydrated through glycolmethacrylate series and embedded in glycolmethacrylate mixture, according to Bernhard's method (Specimen B).

Gold labeling of teichoic acid on adjacent surfaces of staphylococcus aureus

1990 ◽  
Vol 48 (3) ◽  
pp. 578-579
Author(s):  
Margaret Hukee
Keyword(s):  
Staphylococcus Aureus ◽  
Teichoic Acid ◽  
Protein Labeling ◽  
Minimal Amount ◽  
Section Thickness ◽  
Double Labeling ◽  
Parallel Surfaces ◽  
Supporting Membrane

Gold labeling of two antigens (double labeling) is often done on two section surfaces separated by section thickness. Whether labeling is done on both sides of the same section or on two parallel surfaces separated by section thickness (PSSST), comparable results are dependent on an equal number of epitopes being exposed at each surface. We propose a method to study protein labeling within the same field of proteins, by examining two directly adjacent surfaces that were split during sectioning. The number of labeling sites on adjacent surfaces (AS) were compared to sites on PSSST surfaces in individual bacteria.Since each bacteria needed to be recognizable in all three section surfaces, one-hole grids were used for labeling. One-hole grids require a supporting membrane and excessive handling during labeling often ruptures the membrane. To minimize handling, a labeling chamber was designed that is inexpensive, disposable, minimizes contamination, and uses a minimal amount of solution.

Post-operative Staphylococcus aureus infection of a superficial femoral artery stent

VASA ◽  
2013 ◽  
Vol 42 (5) ◽  
pp. 382-386
Author(s):  
Karim Gariani ◽  
Marc Righini ◽  
Marco Roffi ◽  
Gino Gemayel ◽  
Damiano Mugnai ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Femoral Artery ◽  
Superficial Femoral Artery ◽  
Aureus Infection
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