Zehava Eichenbaum

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We characterized the regulated activity of the lactococcal nisA promoter in strains of the gram-positive species Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis, and Bacillus subtilis. nisA promoter activity was dependent on the proteins NisR and NisK, which constitute a two-component signal transduction(More)
The massive erythrocyte lysis caused by the Group A Streptococcus (GAS) suggests that the β-hemolytic pathogen is likely to encounter free heme during the course of infection. In this study, we investigated GAS mechanisms for heme sensing and tolerance. We compared the minimal inhibitory concentration of heme among several isolates and established that(More)
The β-hemolytic group A streptococcus (GAS) is a major pathogen that readily uses hemoglobin to satisfy its requirements for iron. The streptococcal hemoprotein receptor in GAS plays a central role in heme utilization and binds fibronectin and laminin in vitro. Shr inactivation attenuates the virulent M1T1 GAS strain in two murine infection models and(More)
In Group A streptococcus (GAS), the metallorepressor MtsR regulates iron homeostasis. Here we describe a new MtsR-repressed gene, which we named hupZ (heme utilization protein). A recombinant HupZ protein was purified bound to heme from Escherichia coli grown in the presence of 5-aminolevulinic acid and iron. HupZ specifically binds heme with stoichiometry(More)
Group A streptococcus (GAS) is the etiological agent of a variety of local and invasive infections as well as post-infection complications in humans. This β-hemolytic bacterium encounters environmental heme in vivo in a concentration that depends on the infection type and stage. While heme is a noxious molecule, the regulation of cellular heme levels and(More)
Sec translocon is the major machinery for protein translocation in E.coli including Se-cYEG, SecA and other Sec proteins. It is generally assumed that during translocation process, SecYEG serves as a protein-conducting channel and transports the protein across membranes by using SecA ATPase as driving force. However, previous work suggested that protein(More)
The flavivirus resistance gene, Flv, in mice has been identified as 2′-5′ oligoadenylate synthetase 1b (Oas1b). Susceptible mice produce a protein that is truncated (Oas1btr) at the C-terminus due to a premature stop codon encoded by a C820T transition. Mice produce 8 Oas1 proteins, Oas1a-Oas1h. In the present study, Oas1a, Oas1b and Oas1btr were expressed(More)
SecA is a central component of the general secretion system that is essential for growth and virulence of bacteria. A series of fluorescein analogs were tested against AT-Pase activities of Escherichia coli SecA. Rose Bengal (RB) and Erythrosin B are potent inhibitors abolishing the activities of three forms of SecA ATPase with IC 50 in µM range. Both(More)
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