7U55
Crystal structure of Thermoplasmatales archaeon heliorhodopsin at pH 4.5
Summary for 7U55
| Entry DOI | 10.2210/pdb7u55/pdb |
| Descriptor | Heliorhodopsin, RETINAL, CHLORIDE ION, ... (5 entities in total) |
| Functional Keywords | microbial rhodopsin, retinal protein, heliorhodopsin, seven transmembrane protein, membrane protein |
| Biological source | Thermoplasmatales archaeon SG8-52-1 |
| Total number of polymer chains | 1 |
| Total formula weight | 30411.98 |
| Authors | Besaw, J.E.,De Guzman, P.,Miller, R.J.D.,Ernst, O.P. (deposition date: 2022-03-01, release date: 2022-09-07, Last modification date: 2024-11-06) |
| Primary citation | Besaw, J.E.,Reichenwallner, J.,De Guzman, P.,Tucs, A.,Kuo, A.,Morizumi, T.,Tsuda, K.,Sljoka, A.,Miller, R.J.D.,Ernst, O.P. Low pH structure of heliorhodopsin reveals chloride binding site and intramolecular signaling pathway. Sci Rep, 12:13955-13955, 2022 Cited by PubMed Abstract: Within the microbial rhodopsin family, heliorhodopsins (HeRs) form a phylogenetically distinct group of light-harvesting retinal proteins with largely unknown functions. We have determined the 1.97 Å resolution X-ray crystal structure of Thermoplasmatales archaeon SG8-52-1 heliorhodopsin (TaHeR) in the presence of NaCl under acidic conditions (pH 4.5), which complements the known 2.4 Å TaHeR structure acquired at pH 8.0. The low pH structure revealed that the hydrophilic Schiff base cavity (SBC) accommodates a chloride anion to stabilize the protonated retinal Schiff base when its primary counterion (Glu-108) is neutralized. Comparison of the two structures at different pH revealed conformational changes connecting the SBC and the extracellular loop linking helices A-B. We corroborated this intramolecular signaling transduction pathway with computational studies, which revealed allosteric network changes propagating from the perturbed SBC to the intracellular and extracellular space, suggesting TaHeR may function as a sensory rhodopsin. This intramolecular signaling mechanism may be conserved among HeRs, as similar changes were observed for HeR 48C12 between its pH 8.8 and pH 4.3 structures. We additionally performed DEER experiments, which suggests that TaHeR forms possible dimer-of-dimer associations which may be integral to its putative functionality as a light sensor in binding a transducer protein. PubMed: 35977989DOI: 10.1038/s41598-022-17716-9 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.97 Å) |
Structure validation
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