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The effect of host‐encoded nucleoid proteins on transposition: H‐NS influences targeting of both IS 903 and Tn 10
Author(s) -
Swingle Bryan,
O'Carroll Michelle,
Haniford David,
Derbyshire Keith M.
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.1365-2958.2004.04051.x
Subject(s) - tn10 , biology , nucleoid , transposase , transposition (logic) , transposable element , dna , genetics , mutant , microbiology and biotechnology , dna binding protein , escherichia coli , chromosome , gene , transcription factor , linguistics , philosophy
Summary Nucleoid proteins are small, abundant, DNA‐binding proteins that profoundly affect the local and global structure of the chromosome, and play a major role in gene regulation. Although several of these proteins have been shown to enhance assembly of transpososomes before initiating transposition, no systematic survey has been carried out examining the in vivo role(s) of these proteins in transposition. We have examined the requirement of the six most abundant nucleoid proteins in transposition for three different transposons, IS 903 , Tn 10 and Tn 552 . Most notably, H‐NS was required for efficient transposition of all three elements in a papillation assay, suggesting a general role for H‐NS in bacterial transposition. Further studies indicated that H‐NS was exerting its effect on target capture. Targeting preferences for IS 903 into the Escherichia coli chromosome were dramatically altered in the absence of H‐NS. In addition, the alterations observed in the IS 903 target profile emphasized the important role that H‐NS plays in chromosome organization. A defect in target capture was also inferred for Tn 10 , as an excised transposon fragment, a precursor to target capture, accumulated in in vivo induction assays. Furthermore, a transposase mutant that is known to increase target DNA bending and to relax target specificity eliminated this block to target capture. Together, these results imply a role for H‐NS in target capture, either by providing regions of DNA more accessible to transposition or by stabilizing transpososome binding to captured targets immediately before strand transfer.