Orientation of the LexA DNA-binding motif on operator DNA as inferred from cysteine-mediated phenyl azide crosslinking.
AUTOR(ES)
Dumoulin, P
RESUMO
To address the question how the recognition helix of the LexA repressor is positioned within the major groove of operator DNA we have applied a site-specific photocrosslinking approach using a LexA mutant repressor (LexA-C52) that harbors a single cysteine side chain in position 52, close to the COOH terminus of helix 3. The LexA-C52 mutant repressor has been purified and modified site-specifically with the photoreactive azido compound 4-azidophenacyl bromide, giving rise to LexA-C52*. Here we show that LexA-C52* may be selectively photocrosslinked with two adjacent bases within each operator half-site. The crosslinked bases are located, respectively, 10 and 11 base pairs from the dyad axis of the operator. The crosslinking data imply that the LexA recognition helix is oriented opposite to what is generally observed for helix-turn-helix proteins and that this helix should form a steeper angle with respect to the plane of the base pairs than is observed for standard helix-turn-helix proteins.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=46014Documentos Relacionados
- Contacts between the LexA repressor--or its DNA-binding domain--and the backbone of the recA operator DNA.
- A novel DNA-binding motif in the nuclear matrix attachment DNA-binding protein SATB1.
- Characterization of a New LexA Binding Motif in the Marine Magnetotactic Bacterium Strain MC-1
- The gcm-motif: A novel DNA-binding motif conserved in Drosophila and mammals
- Structure of the DNA-binding region of lac repressor inferred from its homology with cro repressor.