Structural highlights
Function
[GYRB_ECOLI] DNA gyrase negatively supercoils closed circular double-stranded DNA in an ATP-dependent manner and also catalyzes the interconversion of other topological isomers of double-stranded DNA rings, including catenanes and knotted rings.[1] [2] [3]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
DNA-gyrase exhibits an unusual ATP-binding site that is formed as a result of gyrase B subunit dimerization, a structural transition that is also essential for DNA capture during the topoisomerization cycle. Previous structural studies on Escherichia coli DNA-gyrase B revealed that dimerization is the result of a polypeptidic exchange involving the N-terminal 14 amino acids. To provide experimental data that dimerization is critical for ATPase activity and enzyme turnover, we generated mutants with reduced dimerization by mutating the two most conserved residues of the GyrB N-terminal arm (Tyr-5 and Ile-10 residues). Our data demonstrate that the hydrophobic Ile-10 residue plays an important role in enzyme dimerization and the nucleotide-protein contact mediated by Tyr-5 side chain residue helps the dimerization process. Analysis of ATPase activities of mutant proteins provides evidence that dimerization enhances the ATP-hydrolysis turnover. The structure of the Y5S mutant of the N-terminal 43-kDa fragment of E. coli DNA GyrB subunit indicates that Tyr-5 residue provides a scaffold for the ATP-hydrolysis center. We describe a channel formed at the dimer interface that provides a structural mechanism to allow reactive water molecules to access the gamma-phosphate group of the bound ATP molecule. Together, these results demonstrate that dimerization strongly contributes to the folding and stability of the catalytic site for ATP hydrolysis. A role for the essential Mg(2+) ion for the orientation of the phosphate groups of the bound nucleotide inside the reactive pocket was also uncovered by superposition of the 5'-adenylyl beta-gamma-imidodiphosphate (ADPNP) wild-type structure to the salt-free ADPNP structure.
Dimerization of Escherichia coli DNA-gyrase B provides a structural mechanism for activating the ATPase catalytic center.,Brino L, Urzhumtsev A, Mousli M, Bronner C, Mitschler A, Oudet P, Moras D J Biol Chem. 2000 Mar 31;275(13):9468-75. PMID:10734094[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Noble CG, Maxwell A. The role of GyrB in the DNA cleavage-religation reaction of DNA gyrase: a proposed two metal-ion mechanism. J Mol Biol. 2002 Apr 26;318(2):361-71. PMID:12051843 doi:http://dx.doi.org/10.1016/S0022-2836(02)00049-9
- ↑ Sissi C, Chemello A, Vazquez E, Mitchenall LA, Maxwell A, Palumbo M. DNA gyrase requires DNA for effective two-site coordination of divalent metal ions: further insight into the mechanism of enzyme action. Biochemistry. 2008 Aug 19;47(33):8538-45. doi: 10.1021/bi800480j. Epub 2008 Jul, 22. PMID:18642932 doi:http://dx.doi.org/10.1021/bi800480j
- ↑ Schoeffler AJ, May AP, Berger JM. A domain insertion in Escherichia coli GyrB adopts a novel fold that plays a critical role in gyrase function. Nucleic Acids Res. 2010 Jul 31. PMID:20675723 doi:10.1093/nar/gkq665
- ↑ Brino L, Urzhumtsev A, Mousli M, Bronner C, Mitschler A, Oudet P, Moras D. Dimerization of Escherichia coli DNA-gyrase B provides a structural mechanism for activating the ATPase catalytic center. J Biol Chem. 2000 Mar 31;275(13):9468-75. PMID:10734094
