Structural Insights into the Activity of Enhancer-Binding Proteins

See allHide authors and affiliations

Science  25 Mar 2005:
Vol. 307, Issue 5717, pp. 1972-1975
DOI: 10.1126/science.1105932

You are currently viewing the abstract.

View Full Text


Activators of bacterial σ54–RNA polymerase holoenzyme are mechanochemical proteins that use adenosine triphosphate (ATP) hydrolysis to activate transcription. We have determined by cryogenic electron microscopy (cryo-EM) a 20 angstrom resolution structure of an activator, phage shock protein F [PspF(1-275)], which is bound to an ATP transition state analog in complex with its basal factor, σ54. By fitting the crystal structure of PspF(1-275) at 1.75 angstroms into the EM map, we identified two loops involved in binding σ54. Comparing enhancer-binding structures in different nucleotide states and mutational analysis led us to propose nucleotide-dependent conformational changes that free the loops for association with σ54.

View Full Text