We deciphered the allosteric functioning mechanism of cytochrome P450cam, which are ubiquitous heme-metalloenzymes involved in multitude of metabolic and industrial reactions as monooxygenases. Despite widely studied, their conformational heterogeneity, its substrate dependence and multi-substrate allostericity could not be understood. We explain that the I helix has intrinsic ability to exist in straight to kinked conformational extremes owing to its constituent G248 and G249 residues. These I helix conformations drive the known conformational changes in channel-1, channel-2 and allosteric coupling between active and allosteric sites, hence serving as the underlying determinant. The I-helix based allosteric mechanism reconcile the 125 crystallographic snaphots with evident straight to kinked conformations of I helix. The substrate-free and substrate-bound NMR PCS measurements can be matched with kinked and straight conformations with Q-scores of 0.108 and 0.061 respectively. The kink generating glycine G249 is remarkably conserved with proability of 0.912, with further signatures of even upto humans. The I-helix based allosteic mechanism also allows for the design of constitutively closed and open P450cam constructs for the first time. Together, our findings provide a departure from traditional FG-helix centric view of cytochrome P450 to a novel I-helix centric view.
 
 

This repository provides associated codes and data for our work on cytochrome P450cam, corresponding to publication -to-be-out-soon

 

The trajectory data files for this work are available on zenodo

 

This work is extension to our previous work on cytochrome P450.

 

Below are our previous publications on cytochrome P450:

 
 

_{Figure (A) The cytochrome P450cam with important structures highlighted, channel-1, channel-2, helices αF, αG, αH, αI and αβ. The three substrate binding modes (catalytic, waiting and allosteric are also shown. (B) Zoomed view of αI with highlighted G248 and G249 residues, respondible for kinking in αI. (C) The αI conformations as observed in simulations and re-examing the crystals structures. (D) The conformations of P450cam as observed in simulations and re-examing crystal structures. (E-G) The conformational correlation plots of αI with αFG (channel-1), L102 (channel-2) and αH (allosteric site).}