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Transcription of Bacteriophage PM2 Involves Phage-Encoded Regulators of Heterologous Origin. Riina H. Männistö, 2003.Bacteriophage PM2 is the only described member of the Corticoviridae family . It is an icosahedral dsDNA virus with a membrane residing underneath the protein coat . PM2 infects some gram-negative Pseudoalteromonas spp . In the present study, we mapped the viral promoters and showed that the PM2 genome consists of three operons . Four new virus genes were assigned based on their function in transcription . Proteins P15 and P16 are shown to repress early transcription, and proteins P13 and P14 are shown to activate late transcription events . The early regulatory region, containing genes for proteins P15 and P16, as well as the newly identified early promoter region in PM2, has significant sequence similarity with the Pseudoalteromonas pAS28 plasmid . P14, the transcription activator for the structural genes, has a zinc finger motif homologous to archaeal and eukaryotic TFIIS-type regulatory factors . The Bacteriophage T4 Transcription Activator MotA Interacts with the Far-C-Terminal Region of the  70 Subunit of Escherichia coli RNA Polymerase.Suchira Pande, 2002.Transcription from bacteriophage T4 middle promoters uses Escherichia coli RNA polymerase together with the T4 transcriptional activator MotA and the T4 coactivator AsiA . AsiA binds tightly within the C-terminal portion of the 70 subunit of RNA polymerase, while MotA binds to the 9-bp MotA box motif, which is centered at -30, and also interacts with
70 . We show here that the N-terminal half of MotA (MotANTD), which is thought to include the activation domain, interacts with the C-terminal region of
70 in an E . coli two-hybrid assay . Replacement of the C-terminal 17 residues of
70 with comparable
38 residues abolishes the interaction with MotANTD in this assay, as does the introduction of the amino acid substitution R608C . Furthermore, in vitro transcription experiments indicate that a polymerase reconstituted with a
70 that lacks C-terminal amino acids 604 to 613 or 608 to 613 is defective for MotA-dependent activation . We also show that a proteolyzed fragment of MotA that contains the C-terminal half (MotACTD) binds DNA with a KD(app) that is similar to that of full-length MotA . Our results support a model for MotA-dependent activation in which protein-protein contact between DNA-bound MotA and the far-C-terminal region of
70 helps to substitute functionally for an interaction between
70 and a promoter -35 element .
Enhanced Mercury Biosorption by Bacterial Cells with Surface-Displayed MerR. Weon Bae, 2003.The metalloregulatory protein MerR, which exhibits high affinity and selectivity toward mercury, was exploited for the construction of microbial biosorbents specific for mercury removal . Whole-cell sorbents were constructed with MerR genetically engineered onto the surface of Escherichia coli cells by using an ice nucleation protein anchor . The presence of surface-exposed MerR on the engineered strains enabled sixfold-higher Hg2+ biosorption than that found in the wild-type JM109 cells . Hg2+ binding via MerR was very specific, with no observable decline even in the presence of 100-fold excess Cd2+ and Zn2+ . The Hg2+ binding property of the whole-cell sorbents was also insensitive to different ionic strengths, pHs, and the presence of metal chelators . Since metalloregulatory proteins are currently available for a wide variety of toxic heavy metals, our results suggest that microbial biosorbents overexpressing metalloregulatory proteins may be used similarly for the cleanup of other important heavy metals .
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