1b04: Difference between revisions

[[Image:1b04.gif|left|200px]]<br /><applet load="1b04" size="350" color="white" frame="true" align="right" spinBox="true"  

BACKGROUND: DNA ligases catalyse phosphodiester bond formation between adjacent bases in nicked DNA, thereby sealing the nick. A key step in the catalytic mechanism is the formation of an adenylated DNA intermediate. The adenyl group is derived from either ATP (in eucaryotes and archaea) or NAD+4 (in bacteria). This difference in cofactor specificity suggests that DNA ligase may be a useful antibiotic target. RESULTS: The crystal structure of the adenylation domain of the NAD+-dependent DNA ligase from Bacillus stearothermophilus has been determined at 2.8 A resolution. Despite a complete lack of detectable sequence similarity, the fold of the central core of this domain shares homology with the equivalent region of ATP-dependent DNA ligases, providing strong evidence for the location of the NAD+-binding site. CONCLUSIONS: Comparison of the structure of the NAD+4-dependent DNA ligase with that of ATP-dependent ligases and mRNA-capping enzymes demonstrates the manifold utilisation of a conserved nucleotidyltransferase domain within this family of enzymes. Whilst this conserved core domain retains a common mode of nucleotide binding and activation, it is the additional domains at the N terminus and/or the C terminus that provide the alternative specificities and functionalities in the different members of this enzyme superfamily.

1B04 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Geobacillus_stearothermophilus Geobacillus stearothermophilus]. Active as [http://en.wikipedia.org/wiki/DNA_ligase_(NAD(+)) DNA ligase (NAD(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.5.1.2 6.5.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1B04 OCA].  

[[Category: Singleton, M R.]]

[[Category: Timson, D J.]]

[[Category: Wigley, D B.]]

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