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Control of IS 911 target selection: how OrfA may ensure IS dispersion
Author(s) -
Rousseau Philippe,
Loot Céline,
Guynet Catherine,
AhSeng Yoan,
TonHoang Bao,
Chandler Mick
Publication year - 2007
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.1365-2958.2007.05615.x
Subject(s) - transposase , biology , zipper , insertion sequence , dna , leucine zipper , genetics , integrases , transposable element , plasmid , transcription factor , gene , mutant , computer science , algorithm
Summary IS 911 transposition involves a closed circular insertion sequence intermediate (IS‐circle) and two IS‐encoded proteins: the transposase OrfAB and OrfA which regulates IS 911 insertion. OrfAB alone promotes insertion preferentially next to DNA sequences resembling IS 911 ends while the addition of OrfA strongly stimulates insertion principally into DNA targets devoid of the IS 911 end sequences. OrfAB shares its N‐terminal region with OrfA. This includes a helix–turn–helix (HTH) motif and the first three of four heptads of a leucine zipper (LZ). OrfAB binds specifically to IS 911 ends via its HTH whereas OrfA does not. We show here: that OrfA binds DNA non‐specifically and that this requires the HTH; that OrfA LZ is required for its multimerization; and that both motifs are essential for OrfA activity. We propose that these OrfA properties are required to assemble a nucleoprotein complex committed to random IS 911 insertion. This control of IS 911 insertion activity by OrfA in this way would assure its dispersion.