Kannan, Priyadharshini Oh, Jisung Yeon, Young Joo Park, Youn-Il Seo, Moon-Hyeong Park, Keunwan 2024-01-19T08:01:35Z 2024-01-19T08:01:35Z 2023-10-29 2024-01 0887-3585 https://pubs.kist.re.kr/handle/201004/112982 Cyanobacteriochromes (CBCRs) are linear tetrapyrrole bilin-binding photoreceptors of cyanobacteria that exhibit high spectral diversity, gaining attention in optogenetics and bioimaging applications. Several engineering studies on CBCRs were attempted, especially for designing near-infrared (NIR) fluorescent proteins with longer fluorescence wavelengths. However, despite continuous efforts, a key component regulating fluorescence emission property in CBCRs is still poorly understood. As a model system, we focused on red/green CBCR Slr1393g3, from the unicellular cyanobacterium Synechocystis sp. PCC 6803 to engineer Pr to get far-red light-emitting property. Energy profiling and pairwise structural comparison of Slr1393g3 variants effectively reveal the mutations that are critical to the fluorescence changes. H497 seems to play a key role in stabilizing the chromophore environment, especially the alpha 3 helix, while H495, T499, and Q502 are potential key residues determining fluorescence emission peak wavelength. We also found that mutations of alpha 2 and alpha 4 helical regions are closely related to the chromophore binding stability and likely affect fluorescence properties. Taken together, our computational analysis suggests that the fluorescence of Slr1393g3 is mainly controlled by the stabilization of the chromophore binding pocket. The predicted key residues potentially regulating the fluorescence emission property of a red/green CBCR will be advantageous for designing improved NIR fluorescent protein when combined with in vitro molecular evolution approaches. English Wiley-Liss Inc Computational identification of key residues regulating fluorescence emission in a red/green cyanobacteriochrome Article 10.1002/prot.26586 1 PROTEINS : Structure, Function, and Bioinformatics, v.92, no.1, pp.106 - 116 PROTEINS : Structure, Function, and Bioinformatics 92 1 106 116 Y scie scopus 001077327200001 2-s2.0-85169312480 Biochemistry & Molecular Biology Biophysics Biochemistry & Molecular Biology Biophysics Article BINDING GAF DOMAIN HYDROGEN-BOND PHOTOCONVERSION DYNAMICS PHYCOCYANOBILIN EFFICIENCY CONVERSION SLR1393 LINEAGE cyanobacteriochrome fluorescence helix stabilization interaction energy Slr1393g3 structural analysis