Intradomain LexA rotation is a prerequisite for DNA binding specificity.
In the absence of DNA damage the LexA protein represses the bacterial SOS system. We performed molecular dynamic simulations of two LexA dimers bound to operators. Our model predicted that rotation of the LexA DNA binding domain, with respect to the dimerised C-terminal domain, is required for selective DNA binding. To confirm the model, double and quadruple cysteine LexA mutants were engineered. Electrophoretic mobility-shift assay and surface plasmon resonance showed that disulfide bond formation between the introduced cysteine residues precluded LexA specific DNA binding due to blocked domain reorientation. Our model could provide the basis for novel drug design.
Butala
Matej
M
Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, Ljubljana, Slovenia. matej.butala@bf.uni-lj.si
Hodoscek
Milan
M
Anderluh
Gregor
G
Podlesek
Zdravko
Z
Zgur-Bertok
Darja
D
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003087:Colicins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D008958:Models, Molecular; D009154:Mutation; D009875:Operator Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012399:Rotation; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D003087:Colicins; D004268:DNA-Binding Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein