Toggle Main Menu Toggle Search

Open Access padlockePrints

Mutagenesis of E477 or K505 in the B' domain of human topoisomerase IIβ increases the requirement for magnesium ions during strand passage

Lookup NU author(s): Dr Emma Meczes, Professor Caroline Austin

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

A type II topoisomerase is essential for decatenating DNA replication products, and it accomplishes this task by passing one DNA duplex through a transient break in a second duplex. The B' domain of topoisomerase II contains three highly conserved motifs, EGDSA, PL(R/K)GK(I/L/M)LNVR, and IMTD(Q/A)DXD. We have investigated these motifs in topoisomerase IIβ by mutagenesis, and report that they play a critical role in establishing the DNA cleavage-religation equilibrium. In addition, the mutations E477Q (EGDSA) and K505E (PLRGKILNVR) increase the optimal magnesium ion concentration for strand passage, without affecting the Mg2+ dependence of ATP hydrolysis. It is likely that the binding affinity of the magnesium ion(s) specifically required for DNA cleavage has been reduced by these mutations. The crystal structure of yeast topo II indicates that residues E477 and K505 may help to position the three aspartate residues of the IMTD(Q/A)DXD motif for magnesium ion coordination, and we propose two possible locations for the magnesium ion binding site(s). These observations are consistent with a previous model in which the B' domain is positioned such that these acidic residues lie next to the active site tyrosine residue. A magnesium ion bound by these aspartate residues could therefore mediate the DNA cleavage-religation reaction.


Publication metadata

Author(s): West KL, Meczes EL, Thorn R, Turnbull RM, Marshall R, Austin CA

Publication type: Article

Publication status: Published

Journal: Biochemistry

Year: 2000

Volume: 39

Issue: 6

Pages: 1223-1233

Print publication date: 15/02/2000

ISSN (print): 0006-2960

ISSN (electronic): 1943-295X

URL: http://dx.doi.org/10.1021/bi991328b

DOI: 10.1021/bi991328b

PubMed id: 10684600


Altmetrics

Altmetrics provided by Altmetric


Actions

Find at Newcastle University icon    Link to this publication


Share