M. Amouyal et al., Adjacent cooperation of proteins on DNA are not representative of long-distance interactions, CR AC S III, 321(11), 1998, pp. 877-881
Citations number
28
Categorie Soggetti
Multidisciplinary,"Experimental Biology
Journal title
COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE III-SCIENCES DE LA VIE-LIFE SCIENCES
The cl repressor of bacteriophage lambda is better-fitted to the proximal i
nteractions in which it naturally takes part than to the long-distance coop
erative interactions on DNA for which it has become representative. The fir
st observation in support of this statement is the ambiguity of an untypica
l DNAase I footprint which has become a diagnostic for DNA circularisation
land thus for the capacity of the protein to control expression at a distan
ce). However, it was also observed without effective DNA looping when lac r
epressor binds to nearly contiguous sites. Additionally, the surface of int
eraction between the two dimers seems to be more important than the one com
monly admitted (via some contacts between the flexible arms), the biologica
l function of the repressor is lost when the sites are separated and loops
have not been observed for large separation of the sites. In fact, naturall
y distant interactions can conform to shorter distances, as an intrinsic pr
operty of DNA looping. On the contrary, interactions which are naturally op
timised for contiguity are generally constrained to proximity. Alternative
protein-protein contacts are generally responsible for this situation (cf.
CRP versus NRI in Escherichia coin. ((C) Academie des sciences / Elsevier,
Paris.)