The inner mechanics of Rhodopsin Guanylyl Cyclase during cGMP-formation revealed by real-time FTIR spectroscopy
- Humboldt-Universität zu Berlin, Germany
- Center of Advanced European Studies and Research, Germany
- Humboldt University of Berlin, Germany
Abstract
Enzymerhodopsins represent a recently discovered class of rhodopsins which includes histidine kinase rhodopsin, rhodopsin phosphodiesterases and rhodopsin guanylyl cyclases (RGCs). The regulatory influence of the rhodopsin domain on the enzyme activity is only partially understood and holds the key for a deeper understanding of intra-molecular signaling pathways. Here we present a UV-Vis and FTIR study about the light-induced dynamics of a RGC from the fungus Catenaria anguillulae, which provides insights into the catalytic process. After the spectroscopic characterization of the late rhodopsin photoproducts, we analyzed truncated variants and revealed the involvement of the cytosolic N-terminus in the structural rearrangements upon photo-activation of the protein. We tracked the catalytic reaction of RGC and the free GC domain independently by UV-light induced release of GTP from the photolabile NPE-GTP substrate. Our results show substrate binding to the dark-adapted RGC and GC alike and reveal differences between the constructs attributable to the regulatory influence of the rhodopsin on the conformation of the binding pocket. By monitoring the phosphate rearrangement during cGMP and pyrophosphate formation in light-activated RGC, we were able to confirm the M state as the active state of the protein. The described setup and experimental design enable real-time monitoring of substrate turnover in light-activated enzymes on a molecular scale, thus opening the pathway to a deeper understanding of enzyme activity and protein-protein interactions.
Data availability
Data files have been provided on Dryad (doi:10.5061/dryad.6wwpzgmzx) for Figure 4 and 5 as well as for the homology structures of the protein presented in the appendices, upon which figure 6 is based. This includes the protein prediction by AlphaFold 2.
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The inner mechanics of rhodopsin guanylyl cyclase during cGMP-formation revealed by real-time FTIR spectroscopyDryad Digital Repository, doi:10.5061/dryad.6wwpzgmzx.
Article and author information
Author details
Shatanik Mukherjee
Funding
Deutsche Forschungsgemeinschaft (221545957 B2+B5)
- Franz Bartl
- Peter Hegemann
Deutsche Forschungsgemeinschaft (SFB1315-327654276)
- Peter Hegemann
Deutsche Forschungsgemeinschaft (390540038)
- Peter Hegemann
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Fischer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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The inner mechanics of Rhodopsin Guanylyl Cyclase during cGMP-formation revealed by real-time FTIR spectroscopy
eLife 10:e71384.
https://doi.org/10.7554/eLife.71384
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