1cez
From Proteopedia
(New page: 200px<br /><applet load="1cez" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cez, resolution 2.40Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1cez.gif|left|200px]]<br /><applet load="1cez" size=" | + | [[Image:1cez.gif|left|200px]]<br /><applet load="1cez" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cez, resolution 2.40Å" /> | caption="1cez, resolution 2.40Å" /> | ||
'''CRYSTAL STRUCTURE OF A T7 RNA POLYMERASE-T7 PROMOTER COMPLEX'''<br /> | '''CRYSTAL STRUCTURE OF A T7 RNA POLYMERASE-T7 PROMOTER COMPLEX'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Although the single-polypeptide-chain RNA polymerase from bacteriophage T7 | + | Although the single-polypeptide-chain RNA polymerase from bacteriophage T7 (T7RNAP), like other RNA polymerases, uses the same mechanism of polymerization as the DNA polymerases, it can also recognize a specific promoter sequence, initiate new RNA chains from a single nucleotide, abortively cycle the synthesis of short transcripts, be regulated by a transcription inhibitor, and terminate transcription. As T7RNAP is homologous to the Pol I family of DNA polymerases, the differences between the structure of T7RNAP complexed to substrates and that of the corresponding DNA polymerase complex provides a structural basis for understanding many of these functional differences. T7RNAP initiates RNA synthesis at promoter sequences that are conserved from positions -17 to +6 relative to the start site of transcription. The crystal structure at 2.4 A resolution of T7RNAP complexed with a 17-base-pair promoter shows that the four base pairs closest to the catalytic active site have melted to form a transcription bubble. The T7 promoter sequence is recognized by interactions in the major groove between an antiparallel beta-loop and bases. The amino-terminal domain is involved in promoter recognition and DNA melting. We have also used homology modelling of the priming and incoming nucleoside triphosphates from the T7 DNA-polymerase ternary complex structure to explain the specificity of T7RNAP for ribonucleotides, its ability to initiate from a single nucleotide, and the abortive cycling at the initiation of transcription. |
==About this Structure== | ==About this Structure== | ||
| - | 1CEZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteriophage_t7 Bacteriophage t7]. Active as [http://en.wikipedia.org/wiki/DNA-directed_RNA_polymerase DNA-directed RNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.6 2.7.7.6] Full crystallographic information is available from [http:// | + | 1CEZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteriophage_t7 Bacteriophage t7]. Active as [http://en.wikipedia.org/wiki/DNA-directed_RNA_polymerase DNA-directed RNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.6 2.7.7.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CEZ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: DNA-directed RNA polymerase]] | [[Category: DNA-directed RNA polymerase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Cheetham, G | + | [[Category: Cheetham, G M.T.]] |
[[Category: Jeruzalmi, D.]] | [[Category: Jeruzalmi, D.]] | ||
| - | [[Category: Steitz, T | + | [[Category: Steitz, T A.]] |
[[Category: t7 rna polymerase]] | [[Category: t7 rna polymerase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:05:26 2008'' |
Revision as of 10:05, 21 February 2008
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CRYSTAL STRUCTURE OF A T7 RNA POLYMERASE-T7 PROMOTER COMPLEX
Overview
Although the single-polypeptide-chain RNA polymerase from bacteriophage T7 (T7RNAP), like other RNA polymerases, uses the same mechanism of polymerization as the DNA polymerases, it can also recognize a specific promoter sequence, initiate new RNA chains from a single nucleotide, abortively cycle the synthesis of short transcripts, be regulated by a transcription inhibitor, and terminate transcription. As T7RNAP is homologous to the Pol I family of DNA polymerases, the differences between the structure of T7RNAP complexed to substrates and that of the corresponding DNA polymerase complex provides a structural basis for understanding many of these functional differences. T7RNAP initiates RNA synthesis at promoter sequences that are conserved from positions -17 to +6 relative to the start site of transcription. The crystal structure at 2.4 A resolution of T7RNAP complexed with a 17-base-pair promoter shows that the four base pairs closest to the catalytic active site have melted to form a transcription bubble. The T7 promoter sequence is recognized by interactions in the major groove between an antiparallel beta-loop and bases. The amino-terminal domain is involved in promoter recognition and DNA melting. We have also used homology modelling of the priming and incoming nucleoside triphosphates from the T7 DNA-polymerase ternary complex structure to explain the specificity of T7RNAP for ribonucleotides, its ability to initiate from a single nucleotide, and the abortive cycling at the initiation of transcription.
About this Structure
1CEZ is a Single protein structure of sequence from Bacteriophage t7. Active as DNA-directed RNA polymerase, with EC number 2.7.7.6 Full crystallographic information is available from OCA.
Reference
Structural basis for initiation of transcription from an RNA polymerase-promoter complex., Cheetham GM, Jeruzalmi D, Steitz TA, Nature. 1999 May 6;399(6731):80-3. PMID:10331394
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