1mmi: Difference between revisions
New page: left|200px<br /><applet load="1mmi" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mmi, resolution 1.848Å" /> '''E. COLI DNA POLYMER... |
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[[Image:1mmi.gif|left|200px]]<br /><applet load="1mmi" size=" | [[Image:1mmi.gif|left|200px]]<br /><applet load="1mmi" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1mmi, resolution 1.848Å" /> | caption="1mmi, resolution 1.848Å" /> | ||
'''E. COLI DNA POLYMERASE BETA SUBUNIT'''<br /> | '''E. COLI DNA POLYMERASE BETA SUBUNIT'''<br /> | ||
==Overview== | ==Overview== | ||
The beta subunit of the Escherichia coli replicative DNA polymerase III | The beta subunit of the Escherichia coli replicative DNA polymerase III holoenzyme is the sliding clamp that interacts with the alpha (polymerase) subunit to maintain the high processivity of the enzyme. The beta protein is a ring-shaped dimer of 40.6 kDa subunits whose structure has previously been determined at a resolution of 2.5 A [Kong et al. (1992), Cell, 69, 425-437]. Here, the construction of a new plasmid that directs overproduction of beta to very high levels and a simple procedure for large-scale purification of the protein are described. Crystals grown under slightly modified conditions diffracted to beyond 1.9 A at 100 K at a synchrotron source. The structure of the beta dimer solved at 1.85 A resolution shows some differences from that reported previously. In particular, it was possible at this resolution to identify residues that differed in position between the two subunits in the unit cell; side chains of these and some other residues were found to occupy alternate conformations. This suggests that these residues are likely to be relatively mobile in solution. Some implications of this flexibility for the function of beta are discussed. | ||
==About this Structure== | ==About this Structure== | ||
1MMI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/DNA-directed_DNA_polymerase DNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.7 2.7.7.7] Full crystallographic information is available from [http:// | 1MMI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/DNA-directed_DNA_polymerase DNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.7 2.7.7.7] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MMI OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Beck, J | [[Category: Beck, J L.]] | ||
[[Category: Dixon, N | [[Category: Dixon, N E.]] | ||
[[Category: Oakley, A | [[Category: Oakley, A J.]] | ||
[[Category: Prosselkov, P.]] | [[Category: Prosselkov, P.]] | ||
[[Category: Wijffels, G.]] | [[Category: Wijffels, G.]] | ||
[[Category: Wilce, M | [[Category: Wilce, M C.J.]] | ||
[[Category: dna polymerase beta subunit]] | [[Category: dna polymerase beta subunit]] | ||
[[Category: dna replication]] | [[Category: dna replication]] | ||
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[[Category: sliding clamp]] | [[Category: sliding clamp]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:56:43 2008'' | ||
Revision as of 14:56, 21 February 2008
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E. COLI DNA POLYMERASE BETA SUBUNIT
OverviewOverview
The beta subunit of the Escherichia coli replicative DNA polymerase III holoenzyme is the sliding clamp that interacts with the alpha (polymerase) subunit to maintain the high processivity of the enzyme. The beta protein is a ring-shaped dimer of 40.6 kDa subunits whose structure has previously been determined at a resolution of 2.5 A [Kong et al. (1992), Cell, 69, 425-437]. Here, the construction of a new plasmid that directs overproduction of beta to very high levels and a simple procedure for large-scale purification of the protein are described. Crystals grown under slightly modified conditions diffracted to beyond 1.9 A at 100 K at a synchrotron source. The structure of the beta dimer solved at 1.85 A resolution shows some differences from that reported previously. In particular, it was possible at this resolution to identify residues that differed in position between the two subunits in the unit cell; side chains of these and some other residues were found to occupy alternate conformations. This suggests that these residues are likely to be relatively mobile in solution. Some implications of this flexibility for the function of beta are discussed.
About this StructureAbout this Structure
1MMI is a Single protein structure of sequence from Escherichia coli. Active as DNA-directed DNA polymerase, with EC number 2.7.7.7 Full crystallographic information is available from OCA.
ReferenceReference
Flexibility revealed by the 1.85 A crystal structure of the beta sliding-clamp subunit of Escherichia coli DNA polymerase III., Oakley AJ, Prosselkov P, Wijffels G, Beck JL, Wilce MC, Dixon NE, Acta Crystallogr D Biol Crystallogr. 2003 Jul;59(Pt 7):1192-9. Epub 2003, Jun 27. PMID:12832762
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