2p5t
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(New page: 200px<br /><applet load="2p5t" size="350" color="white" frame="true" align="right" spinBox="true" caption="2p5t, resolution 3.20Å" /> '''Molecular and struct...)
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Revision as of 12:19, 23 January 2008
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Molecular and structural characterization of the PezAT chromosomal toxin-antitoxin system of the human pathogen Streptococcus pneumoniae
Overview
The chromosomal pezT gene of the Gram-positive pathogen Streptococcus, pneumoniae encodes a protein that is homologous to the zeta toxin of the, Streptococcus pyogenes plasmid pSM19035-encoded epsilon-zeta, toxin-antitoxin system. Overexpression of pezT in Escherichia coli led to, severe growth inhibition from which the bacteria recovered approximately 3, h after induction of expression. The toxicity of PezT was counteracted by, PezA, which is encoded immediately upstream of pezT and shares weak, sequence similarities in the C-terminal region with the epsilon antitoxin., The pezAT genes form a bicistronic operon that is co-transcribed from a, sigma(70)-like promoter upstream of pezA and is negatively autoregulated, with PezA functioning as a transcriptional repressor and PezT as a, co-repressor. Both PezA and the non-toxic PezA(2)PezT(2) protein complex, bind to a palindrome sequence that overlaps the promoter. This differs, from the epsilon-zeta system in which epsilon functions solely as the, antitoxin and transcriptional regulation is carried out by another protein, designated omega. Results from site-directed mutagenesis experiments, demonstrated that the toxicity of PezT is dependent on a highly conserved, phosphoryltransferase active site and an ATP/GTP nucleotide binding site., In the PezA(2)PezT(2) complex, PezA neutralizes the toxicity of PezT by, blocking the nucleotide binding site through steric hindrance.
About this Structure
2P5T is a Protein complex structure of sequences from Streptococcus pneumoniae. Full crystallographic information is available from OCA.
Reference
Molecular and structural characterization of the PezAT chromosomal toxin-antitoxin system of the human pathogen Streptococcus pneumoniae., Khoo SK, Loll B, Chan WT, Shoeman RL, Ngoo L, Yeo CC, Meinhart A, J Biol Chem. 2007 Jul 6;282(27):19606-18. Epub 2007 May 8. PMID:17488720
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