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Gal or Lac repressor binding to an upstream DNA segment, in the absence of DNA looping, represses the P1 promoter located on the same face and activates the P2 promoter situated on the opposite face of the DNA helix in the gal operon. Both inhibition and stimulation of transcription requires the physical presence of the C-terminal domain of the alpha(More)
HflX is a GTP binding protein of unknown function. Based on the presence of the hflX gene in hflA operon, HflX was believed to be involved in the lytic-lysogenic decision during phage infection in Escherichia coli. We find that E. coli HflX binds 16S and 23S rRNA - the RNA components of 30S and 50S ribosomal subunits. Here, using purified ribosomal(More)
The gal operon of Escherichia coli is negatively regulated by repressor binding to bipartite operators separated by 11 helical turns of DNA. Synergistic binding of repressor to separate sites on DNA results in looping, with the intervening DNA as a topologically closed domain containing the two promoters. A closed DNA loop of 11 helical turns, which is(More)
The CIII protein of bacteriophage lambda exhibits antiproteolytic activity against the ubiquitous metalloprotease HflB (FtsH) of Escherichia coli, thereby stabilizing the lambdaCII protein and promoting lysogenic development of the phage. CIII also protects E.coli sigma(32), another substrate of HflB. We have recently shown that the protection of CII from(More)
A crucial element in the lysis-lysogeny decision of the temperate coliphage lambda is the phage protein CII, which has several interesting properties. It promotes lysogeny through activation of three phage promoters p(E), p(I) and p(aQ), recognizing a direct repeat sequence TTGCN6TTGC at each. The three-dimensional structure of CII, a homo-tetramer of 97(More)
The temperate coliphage lambda, after infecting its host bacterium Escherichia coli, can develop either along the lytic or the lysogenic pathway. Crucial to the lysis/lysogeny decision is the homotetrameric transcription-activator protein CII (4 x 11 kDa) of the phage that binds to a unique direct-repeat sequence T-T-G-C-N6-T-T-G-C at each of the three(More)
The CIII protein encoded by the temperate coliphage lambda acts as an inhibitor of the ubiquitous Escherichia coli metalloprotease HflB (FtsH). This inhibition results in the stabilization of transcription factor lambdaCII, thereby helping the phage to lysogenize the host bacterium. LambdaCIII, a small (54-residue) protein of unknown structure, also(More)
The Escherichia coli gene hflX was first identified as part of the hflA operon, mutations in which led to an increased frequency of lysogenization upon infection of the bacterium by the temperate coliphage lambda. Independent mutational studies have also indicated that the HflX protein has a role in transposition. Based on the sequence of its gene, HflX is(More)
The CII protein of the temperate bacteriophage lambda is the decision-making factor that determines the viral lytic/lysogenic choice. It is a homotetrameric transcription activator that recognizes and binds specific direct repeat sequences TTGCN(6)TTGC in the lambda genome. The quaternary structure of CII is held by a four-helix bundle. It is known that the(More)
Manganese is a micronutrient required for activities of several important enzymes under conditions of oxidative stress and iron starvation. In Escherichia coli, the manganese homeostasis network primarily constitutes a manganese importer (MntH) and an exporter (MntP), which are regulated by the MntR dual regulator. In this study, we find that deletion of E.(More)