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The resistance-nodulation-division type tripartite pump AcrAB-TolC and its homologs are responsible for multidrug resistance in Gram-negative bacteria by expelling a wide variety of toxic substrates. The three essential components, AcrA, AcrB, and TolC, must function in concert with each respective binding partner within the complex. In this study, we(More)
Gram-negative bacteria are capable of expelling diverse xenobiotic substances from within the cell by use of three-component efflux pumps in which the energy-activated inner membrane transporter is connected to the outer membrane channel protein via the membrane fusion protein. In this work, we describe the crystal structure of the membrane fusion protein(More)
Escherichia coli AcrAB-TolC is a multidrug efflux pump that expels a wide range of toxic substrates. The dynamic nature of the binding or low affinity between the components has impeded elucidation of how the three components assemble in the functional state. Here, we created fusion proteins composed of AcrB, a transmembrane linker, and two copies of AcrA.(More)
Early growth response-1 (Egr-1), a zinc finger transcription factor, plays a key regulatory role in pathological cardiovascular processes including atherosclerosis. Here, we investigate whether Egr-1 expression and foam cell formation require toll-like receptor 9 (TLR9) and myeloid differentiation factor 88 (MyD88). CpG DNA and its related synthetic CpG(More)
OxyR, a bacterial peroxide sensor, is a LysR-type transcriptional regulator (LTTR) that regulates the transcription of defense genes in response to a low level of cellular H2O2. Consisting of an N-terminal DNA-binding domain (DBD) and a C-terminal regulatory domain (RD), OxyR senses H2O2 with conserved cysteine residues in the RD. However, the precise(More)
The disulfide-bond isomerase DsbC plays a crucial role in the folding of bacterial proteins in the periplasmic space. DsbC has a V-shaped dimeric structure with two domains, and Cys98 in the C-terminal domain attacks inappropriate disulfide bonds in substrate proteins due to its high nucleophilic activity. In this article, we present the crystal structure(More)
An intracellular α-amylase, AmyB, has been cloned from the hyperthermophilic bacterium Thermotoga neapolitana. AmyB belongs to glycoside hydrolase family 13 and liberates maltose from diverse substrates, including starch, amylose, amylopectin and glycogen. The final product of AmyB is similar to that of typical maltogenic amylases, but AmyB cleaves maltose(More)
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative intracellular pathogen with the ability to survive and replicate in macrophages. Periplasmic copper binding protein CueP is known to confer copper resistance to S. Typhimurium, and has been implicated in ROS scavenge activity by transferring the copper ion to a periplasmic superoxide(More)
Macrophage activation contributes to the pathogenesis of atherosclerosis. In the vascular system, the major source of reactive oxygen species is the NADPH oxidase (Nox) family. Nox1 is induced by lipopolysaccharide (LPS) in macrophages, but the expression mechanism is not fully understood. We found that LPS causes beta-catenin accumulation by glycogen(More)
Lysozymes are the first line of defense for a diverse range of organisms that catalyze the degradation of bacterial peptidoglycan. Gram-negative bacteria produce proteinaceous lysozyme inhibitors to protect themselves from the action of lysozymes. To date, MliC or PliC (membrane-bound or periplasmic inhibitor of c-type lysozyme, respectively) has been found(More)