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.
Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, 118 Route de Narbonne, F-31062 Toulouse Cedex, France. philippe.rousseau@ibcg.biotoul.fr
Philippe
P
Rousseau
Erwan
E
Gueguen
Guy
G
Duval-Valentin
Mick
M
Chandler
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