The helix-turn-helix motif of bacterial insertion sequence IS911 transposase is required for DNA binding.
The transposase of IS911, a member of the IS3 family of bacterial insertion sequences, is composed of a catalytic domain located at its C-terminal end and a DNA binding domain located at its N-terminal end. Analysis of the transposases of over 60 members of the IS3 family revealed the presence of a helix-turn-helix (HTH) motif within the N-terminal region. Alignment of these potential secondary structures further revealed a completely conserved tryptophan residue similar to that found in the HTH motifs of certain homeodomain proteins. The analysis also uncovered a similarity between the IS3 family HTH and that of members of the LysR family of bacterial transcription factors. This information was used to design site-directed mutations permitting an assessment of its role in transposase function. A series of in vivo and in vitro tests demonstrated that the HTH domain is important in directing the transposase to bind the terminal inverted repeats of IS911.
Rousseau
Philippe
P
Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, 118 Route de Narbonne, F-31062 Toulouse Cedex, France. philippe.rousseau@ibcg.biotoul.fr
Gueguen
Erwan
E
Duval-Valentin
Guy
G
Chandler
Mick
M
D001419:Bacteria / Q000201:enzymology*; D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D019077:Helix-Turn-Helix Motifs; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D012984:Software; D019895:Transposases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D004247:DNA; D019895:Transposases