1kej: Difference between revisions

[[Image:1kej.jpg|left|200px]]<br /><applet load="1kej" size="350" color="white" frame="true" align="right" spinBox="true"  

The crystal structure of the catalytic core of murine terminal deoxynucleotidyltransferase (TdT) at 2.35 A resolution reveals a typical DNA polymerase beta-like fold locked in a closed form. In addition, the structures of two different binary complexes, one with an oligonucleotide primer and the other with an incoming ddATP-Co(2+) complex, show that the substrates and the two divalent ions in the catalytic site are positioned in TdT in a manner similar to that described for the human DNA polymerase beta ternary complex, suggesting a common two metal ions mechanism of nucleotidyl transfer in these two proteins. The inability of TdT to accommodate a template strand can be explained by steric hindrance at the catalytic site caused by a long lariat-like loop, which is absent in DNA polymerase beta. However, displacement of this discriminating loop would be sufficient to unmask a number of evolutionarily conserved residues, which could then interact with a template DNA strand. The present structure can be used to model the recently discovered human polymerase mu, with which it shares 43% sequence identity.

1KEJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with <scene name='pdbligand=CO:'>CO</scene>, <scene name='pdbligand=NA:'>NA</scene> and <scene name='pdbligand=DAD:'>DAD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/DNA_nucleotidylexotransferase DNA nucleotidylexotransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.31 2.7.7.31] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KEJ OCA].  

[[Category: Boule, J B.]]

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