{"title":"SNap Bond, a Crucial Hydrogen Bond Between Ser in Helix 3 and Asn in Helix 4, Regulates the Structural Dynamics of Heliorhodopsin","authors":"Toshiki Nakamura , Manish Singh , Masahiro Sugiura , Soichiro Kato , Ryo Yamamoto , Hideki Kandori , Yuji Furutani","doi":"10.1016/j.jmb.2024.168666","DOIUrl":null,"url":null,"abstract":"<div><p>Heliorhodopsin (HeR) is a new rhodopsin family discovered in 2018 through functional metagenomic analysis. Similar to microbial rhodopsins, HeR has an all-<em>trans</em> retinal chromophore, and its photoisomerization to the 13-<em>cis</em> form triggers a relatively slow photocycle with sequential intermediate states (K, M, and O intermediates). The O intermediate has a relatively long lifetime and is a putative active state for transferring signals or regulating enzymatic reactions. Although the first discovered HeR, 48C12, was found in bacteria and the second HeR (TaHeR) was found in archaea, their key amino acid residues and molecular architectures have been recognized to be well conserved. Nevertheless, the rise and decay kinetics of the O intermediate are faster in 48C12 than in TaHeR. Here, using a new infrared spectroscopic technique with quantum cascade lasers, we clarified that the hydrogen bond between transmembrane helices (TM) 3 and 4 is essential for the altered O kinetics (Ser112 and Asn138 in 48C12). Interconverting mutants of 48C12 and TaHeR clearly revealed that the hydrogen bond is important for regulating the dynamics of the O intermediate. Overall, our study sheds light on the importance of the hydrogen bond between TM3 and TM4 in heliorhodopsins, similar to the DC gate in channelrhodopsins.</p></div>","PeriodicalId":369,"journal":{"name":"Journal of Molecular Biology","volume":null,"pages":null},"PeriodicalIF":4.7000,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0022283624002614/pdfft?md5=756e9d602b8ef17541095027a93f9011&pid=1-s2.0-S0022283624002614-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Molecular Biology","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022283624002614","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Heliorhodopsin (HeR) is a new rhodopsin family discovered in 2018 through functional metagenomic analysis. Similar to microbial rhodopsins, HeR has an all-trans retinal chromophore, and its photoisomerization to the 13-cis form triggers a relatively slow photocycle with sequential intermediate states (K, M, and O intermediates). The O intermediate has a relatively long lifetime and is a putative active state for transferring signals or regulating enzymatic reactions. Although the first discovered HeR, 48C12, was found in bacteria and the second HeR (TaHeR) was found in archaea, their key amino acid residues and molecular architectures have been recognized to be well conserved. Nevertheless, the rise and decay kinetics of the O intermediate are faster in 48C12 than in TaHeR. Here, using a new infrared spectroscopic technique with quantum cascade lasers, we clarified that the hydrogen bond between transmembrane helices (TM) 3 and 4 is essential for the altered O kinetics (Ser112 and Asn138 in 48C12). Interconverting mutants of 48C12 and TaHeR clearly revealed that the hydrogen bond is important for regulating the dynamics of the O intermediate. Overall, our study sheds light on the importance of the hydrogen bond between TM3 and TM4 in heliorhodopsins, similar to the DC gate in channelrhodopsins.
期刊介绍:
Journal of Molecular Biology (JMB) provides high quality, comprehensive and broad coverage in all areas of molecular biology. The journal publishes original scientific research papers that provide mechanistic and functional insights and report a significant advance to the field. The journal encourages the submission of multidisciplinary studies that use complementary experimental and computational approaches to address challenging biological questions.
Research areas include but are not limited to: Biomolecular interactions, signaling networks, systems biology; Cell cycle, cell growth, cell differentiation; Cell death, autophagy; Cell signaling and regulation; Chemical biology; Computational biology, in combination with experimental studies; DNA replication, repair, and recombination; Development, regenerative biology, mechanistic and functional studies of stem cells; Epigenetics, chromatin structure and function; Gene expression; Membrane processes, cell surface proteins and cell-cell interactions; Methodological advances, both experimental and theoretical, including databases; Microbiology, virology, and interactions with the host or environment; Microbiota mechanistic and functional studies; Nuclear organization; Post-translational modifications, proteomics; Processing and function of biologically important macromolecules and complexes; Molecular basis of disease; RNA processing, structure and functions of non-coding RNAs, transcription; Sorting, spatiotemporal organization, trafficking; Structural biology; Synthetic biology; Translation, protein folding, chaperones, protein degradation and quality control.