Abstract
The mesoscale nature of proteins allows for an efficient coupling between environmental cues and conformational changes, enabling their function as molecular transducers. Delineating the precise structural origins of such a connection and the expected spectroscopic response has, however, been challenging. In this work, we perform a combination of urea–temperature double perturbation experiments and theoretical modeling to probe the conformational landscape of Cnu, a natural thermosensor protein. We observe unique ensemble signatures that point to a continuum of conformational substates in the native ensemble and that respond intricately to perturbations upon monitoring secondary and tertiary structures, distances between an intrinsic FRET pair, and hydrodynamic volumes. Binding assays further reveal a weakening of the Cnu functional complex with temperature, highlighting the molecular origins of signal transduction critical for pathogenic response in enterobacteriaceae.
Highlights
The mesoscale nature of proteins allows for an efficient coupling between environmental cues and conformational changes, enabling their function as molecular transducers
Double-perturbation experiments involving cosolvents and temperature reveal distinct signal dependencies in globally downhill and incipient downhill folders,[8,9] arising from the differences in the structural features of ensembles that are populated in response to one perturbation and that are tuned by another. Such an intrinsically tunable landscape allows for proteins to act as molecular transducers or rheostats; that is, they couple the changes in ambient conditions to their conformations that in turn can determine the functional response.[10]
It was recently identified that the four-helix bundle protein Cnu (Figure 1a), a single gene product, displays thermosensor-like properties that are critical for efficient pathogenic response in enterobacteriaceae that commonly infect human gastrointestinal tracts.[11]
Summary
Amplitude of this component decreases linearly with temperature and changes sign (positive to negative) at specific temperatures as a function of urea (Figure 2e) This observation is in accordance with the predictions of the WSME model that points to this dependence to be originating from the differences in the populations of N and N* (Figure 1e).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
