Substrate recognition and catalysis by the Holliday junction resolving enzyme Hje
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2004
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Resumo |
Two archaeal Holliday junction resolving enzymes, Holliday junction cleavage (Hjc) and Holliday junction endonuclease (Hje), have been characterized. Both are members of a nuclease superfamily that includes the type II restriction enzymes, although their DNA cleaving activity is highly specific for four-way junction structure and not nucleic acid sequence. Despite 28% sequence identity, Hje and Hjc cleave junctions with distinct cutting patterns—they cut different strands of a four-way junction, at different distances from the junction centre. We report the high-resolution crystal structure of Hje from Sulfolobus solfataricus. The structure provides a basis to explain the differences in substrate specificity of Hje and Hjc, which result from changes in dimer organization, and suggests a viral origin for the Hje gene. Structural and biochemical data support the modelling of an Hje:DNA junction complex, highlighting a flexible loop that interacts intimately with the junction centre. A highly conserved serine residue on this loop is shown to be essential for the enzyme's activity, suggesting a novel variation of the nuclease active site. The loop may act as a conformational switch, ensuring that the active site is completed only on binding a four-way junction, thus explaining the exquisite specificity of these enzymes. |
Formato |
application/pdf |
Identificador | |
Publicador |
Oxford Journals |
Relação |
http://eprints.qut.edu.au/40629/1/40629.pdf DOI:10.1093/nar/gkh869 Middleton, Claire L., Parker, Joanne L., Richard, Derek J., White, Malcolm F., & Bond, Charles S. (2004) Substrate recognition and catalysis by the Holliday junction resolving enzyme Hje. Nucleic Acids Research, 32(18), pp. 5442-5451. |
Direitos |
Copyright 2004 Oxford Journals This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/2.5), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Fonte |
Faculty of Science and Technology |
Palavras-Chave | #Holliday junction cleavage #enzymes #Holliday junction endonuclease |
Tipo |
Journal Article |