Disease relevance of T7p20

• Use of bacteriophage T7 lysozyme to improve an inducible T7 expression system [1].
• Cloning a T7 autogene in a derivative of plasmid pBR322 in Escherichia coli was achieved by a combination of blocking initiation at the T7 promoter with bound lac repressor and inhibiting the polymerase itself by T7 lysozyme [2].
• NMR structure of Citrobacter freundii AmpD, comparison with bacteriophage T7 lysozyme and homology with PGRP domains [3].

High impact information on T7p20

• T7 lysozyme inhibits transcription by T7 RNA polymerase [4].
• The 2.8 A crystal structure of the complex reveals that lysozyme binds at a site remote from the polymerase active site, suggesting an indirect mechanism of inhibition [5].
• The T7 RNA polymerase-T7 lysozyme complex regulates phage gene expression during infection of Escherichia coli [5].
• Alignment of the zinc ligands of T7 lysozyme with those of carboxypeptidase A and thermolysin suggests structural similarity among the catalytic sites for the amidase and these zinc proteases [6].
• Although the decrease in the rate of T7 RNA synthesis is independent of DNA replication, the failure to shut off class II RNA synthesis normally in 3.5-- -infected cells may reflect the role of T7 lysozyme in DNA replication [7].

Chemical compound and disease context of T7p20

• The size of lysozyme mRNA from T7-infected E. coli RNase III+ and RNase III- strains was analyzed by sucrose gradient sedimentation, dimethylsulfoxide (Me2SO) sucorse gradient sedimentation, and preparative gel electrophoresis [8].

Biological context of T7p20

• Higher levels of lysozyme supplied by plasmids pLysE or pLysH reduce the fully induced activity of T7 RNA polymerase such that induced cells can continue to grow and produce innocuous target proteins indefinitely [1].
• These lysozyme-hypersensitive polymerases behave without lysozyme similarly to wild-type polymerase with lysozyme: both remain longer at the promoter before establishing a lysozyme-resistant elongation complex and both increase the length of pausing when elongation complexes encounter an eight-base recognition sequence involved in DNA packaging [9].
• Investigation of the pre-steady-state kinetics of transcription in the presence and absence of T7 lysozyme indicated that the inhibition of runoff product synthesis was largely due to inhibition of transcription initiation and transition from initiation to elongation [10].
• Furthermore, a sequence homology comparison with phage T7 lysozyme, also an N-acetylmuramoyl-l-alanine amidase, shows that as many as six of the Drosophila PGRPs could belong to this class of proteins [11].
• Artificial deletion of lysozyme greatly reduced fitness and delayed lysis, but after evolution both phenotypes approached wild-type values [12].

Anatomical context of T7p20

• The lysozyme of bacteriophage T7 is a bifunctional protein that cuts amide bonds in the bacterial cell wall and binds to and inhibits transcription by T7 RNA polymerase [6].

Associations of T7p20 with chemical compounds

• The T7 RNA polymerase-nuclease is inhibited by T7 lysozyme and heparin, although not completely [13].
• The enzyme was purified from the ribosomal wash fraction by conventional methods, affinity chromatography on Cibacron blue and on lysozyme coupled to Sepharose, and by cellogel electrophoresis [14].

Physical interactions of T7p20

• Structure of T7 RNA polymerase complexed to the transcriptional inhibitor T7 lysozyme [5].

Other interactions of T7p20

• Low levels of T7 lysozyme supplied by plasmids pLysS or pLysL, which are compatible with the pET vectors for expressing genes from a T7 promoter, are sufficient to stabilize many target plasmids and yet allow high levels of target protein to be produced upon induction of T7 RNA polymerase [1].
• The presence of T7 lysozyme has the further advantage of facilitating the lysis of cells in preparing extracts for purification of target gene products [1].

Analytical, diagnostic and therapeutic context of T7p20

• The structure of a mutant T7 lysozyme has been determined by x-ray crystallography and refined at 2.2-A resolution [6].
• HPLC gel-filtration experiments demonstrated complex formation between T7 lysozyme, T7 RNA polymerase, and promoter DNA [10].
• This overcomes the inhibitory effect of T7 lysozyme on T7 RNA polymerase as shown by SDS PAGE and flow cytometry analysis of expressed GFP [15].

References