Premium
DNA binding properties of TnpX indicate that different synapses are formed in the excision and integration of the Tn 4451 family
Author(s) -
Adams Vicki,
Lucet Isabelle S.,
Lyras Dena,
Rood Julian I.
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04198.x
Subject(s) - recombinase , tn3 transposon , site specific recombination , biology , integrase , integrases , genetics , transposable element , serine , dna , transposase , cre recombinase , binding site , biochemistry , recombination , gene , genome , transgene , phosphorylation , genetically modified mouse
Summary Site‐specific recombination is an important mechanism for genetic exchange. Insertional recombination mediated by the recently delineated large resolvase or serine recombinase proteins is unique within the resolvase family as integration was thought to be a reaction catalysed only by members of the integrase or tyrosine recombinase family of site‐specific recombinases. The large resolvase TnpX is a serine recombinase that is responsible for the movement of the Tn 4451/3 family of chloramphenicol resistance elements, which are found within two genera of the medically important clostridia. Deletion analysis of TnpX showed that the last 110 amino acids (aa) of TnpX, which comprise a cysteine rich region, were not essential for its biological function and that a region required for DNA binding was located between aa 493–597. Purified TnpX was shown to bind to the ends of the element and to the joint of the circular intermediate with high affinity but, most unusually, to bind to its target sites with a considerably lower affinity. Therefore, it was concluded that the resolvase‐like excision and insertion reactions mediated by TnpX were distinct processes even though the same serine recombinase mechanism was involved. TnpX is the first large serine recombinase in which differential binding to its transposon and target sites has been demonstrated.