Constrained dynamics of the sole tryptophan in the third intracellular loop of the serotonin 1 A receptor

Pal, Sreetama; Aute, Ramdas; Sarkar, Parijat; Bose, Shroddha; Deshmukh, Mandar V.; Chattopadhyay, Amitabha

doi:10.1016/j.bpc.2018.05.008

Cited by 13 publications

(6 citation statements)

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“…Both Aj5‐HT 4/6 and the previously reported Aj5‐HT 4 have the NPXXY motif for receptor desensitization and internalization. The predicted 3D molecular structure of Aj5‐HT 4/6 revealed a long third intracellular loop (IC3) indicating the relationship between this 5‐HT receptor and 5‐HT 1 family (with long IC3 structure) (Albert & Tiberi, 2001; Pal et al, 2018). However, the detailed multiple sequences alignment failed to find out the conservation of predicted IC3 amino acid sequences between Aj5‐HT 4/6 and 5‐HT 1 receptors.…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

et al. 2021

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Serotonin (5‐hydroxytryptamine [5‐HT]) receptors (5‐HTRs) mediate neuroendocrine signaling via interactions with the ligand serotonin (5‐HT). The 5‐HT signaling system has been well studied in vertebrates, but rarely known in invertebrate animals, especially in the marine invertebrates. In this study, we identified and characterized a novel 5‐HTR from the sea cucumber Apostichopus japonicus (Aj5‐HT4/6). The cloned Aj5‐HT4/6 open reading frame comprised 1290 bp and encoded 429 amino acids. Bioinformatic analysis of the receptor indicated that it was a member of the class A of the G protein‐coupled receptor family. Further experiments using Aj5‐HT4/6‐transfected HEK293 cells demonstrated that treatment with 5‐HT could induce rapid internalization of Aj5‐HT4/6 fused with enhanced green fluorescent protein from the cell surface into the cytoplasm and triggered a significant increase in levels of the second messenger cAMP as well as mitogen‐activated protein kinase phosphorylation in a 5‐HT dose‐dependent manner. Quantitative real time‐polymerase chain reaction demonstrated that Aj5‐HT4/6 was predominantly expressed in the muscle and respiratory tree, and its expression was significantly decreased during estivation. Taken together, these results imply that Aj5‐HT4/6 is potentially involved in the movement and metabolism of the sea cucumber.

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Section: Discussionmentioning

confidence: 99%

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

et al. 2021

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“…The concentration of urea was estimated using a Brixxus CRI375P-01U refractometer (Sartorius AG, Goettingen, Germany), as reported earlier. 39 Fluorescence Measurements. Steady state fluorescence measurements were carried out in a Fluorolog-3 Model FL3-22 spectrofluorometer (Jobin Yvon, Edison, NJ) using semimicro quartz cuvettes.…”

Section: Methodsmentioning

confidence: 99%

“…Denaturation was carried out by incubating protein samples with 8 M urea (BioUltra grade) in the dark for 2 h prior to data acquisition. The concentration of urea was estimated using a Brixxus CRI375P-01U refractometer (Sartorius AG, Goettingen, Germany), as reported earlier …”

Section: Methodsmentioning

confidence: 99%

Comparative Analysis of Tryptophan Dynamics in Spectrin and Its Constituent Domains: Insights from Fluorescence

et al. 2021

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Spectrin is a cytoskeletal protein ubiquitous in metazoan cells that acts as a liaison between the plasma membrane and the cellular interior and imparts mechanical stability to the plasma membrane. Spectrin is known to be highly dynamic, with an appreciable degree of torsional and segmental mobility. In this context, we have earlier utilized the red edge excitation shift (REES) approach to report the retention of restricted solvation dynamics and local structure in the vicinity of spectrin tryptophans on urea denaturation and loss of spectrin secondary structure. As a natural progression of our earlier work, in this work, we carried out a biophysical dissection of tryptophan solvation and rotational dynamics in spectrin and its constituent domains, in order to trace the origin of local structure retention observed in denatured spectrin. Our results show that the ankyrin binding domain (and, to a lesser extent, the β-tetramerization domain) is capable of retention of local structure, similar to that observed for intact spectrin. However, all α-chain domains studied exhibit negligible retention of local structure on urea denaturation. Such a stark chain-specific retention of local structure could originate from the fact that the β-chain domains possess specialized functions, where conservation of local (structural) integrity may be a prerequisite for optimum cellular function. To the best of our knowledge, these observations represent one of the first systematic biophysical dissections of spectrin dynamics in terms of its constituent domains and add to emerging literature on comprehensive domain-based analysis of spectrin organization, dynamics, and function.

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“…The human β 2 -adrenergic receptor (β 2 AR) is among the best-characterized rhodopsin-like GPCRs and is highly expressed in pulmonary and cardiac myocyte tissues and thus associated with asthma and heart failure. , Since the first reported X-ray structure of the receptor in 2007, several other structures representing both active and inactive states have been unraveled through X-ray studies. A substantial amount of research has been carried out to understand the dynamic features of β 2 AR involved in several disease mechanisms. − However, one of the major drawbacks of these studies was the missing intracellular loop region (ICL3), which is known to have a central role in GPCR’s intrinsic dynamics. − Complete knowledge of the receptor’s function associated with the disease mechanism requires a complete understanding of its structural and dynamic characteristics.…”

Section: Introductionmentioning

confidence: 95%

Intrinsic Dynamics and Causality in Correlated Motions Unraveled in Two Distinct Inactive States of Human β₂-Adrenergic Receptor

Sogunmez

Akten

2019

J. Phys. Chem. B

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The alternative inactive state of the human β 2adrenergic receptor originally exposed in molecular dynamics simulations was investigated using various analysis tools to evaluate causality between correlated residue-pair fluctuations and suggest allosteric communication pathways. A major conformational shift observed in the third intracellular loop (ICL3) displayed a novel inactive state, featuring an inaccessible G protein binding site blocked by ICL3 and an expanded orthosteric ligand binding site. Residue-based meansquare fluctuation and stiffness calculations revealed a significant mobility decrease in ICL3, which induced a mobility increase in the remaining loop regions. This indicates conformational entropy loss in one mobile region being compensated by residual intermolecular motions in other mobile regions. Moreover, the extent of significantly correlated motions decreased, and correlations that once existed between transmembrane helices shifted toward regions with increased mobility. Conditional time-delayed cross-correlation analysis identified distinct driver−follower relationship profiles. Prior to its packing, freely moving ICL3 was markedly driven by transmembrane helix-8 whereas once packed, ICL3 controlled future fluctuations of nearby helices. Moreover, two transmembrane helices, (H5 and H6), started to control future fluctuations of a remote site, the extracellular loop, ECL2. This clearly suggests that allosteric coupling between extra-and intracellular parts intensified, in agreement with the receptor's well recognized feature, which is the inverse proportionality between activity and the degree of coupling.

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Constrained dynamics of the sole tryptophan in the third intracellular loop of the serotonin 1 A receptor

Cited by 13 publications

References 60 publications

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

Comparative Analysis of Tryptophan Dynamics in Spectrin and Its Constituent Domains: Insights from Fluorescence

Intrinsic Dynamics and Causality in Correlated Motions Unraveled in Two Distinct Inactive States of Human β₂-Adrenergic Receptor

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Constrained dynamics of the sole tryptophan in the third intracellular loop of the serotonin 1 A receptor

Cited by 13 publications

References 60 publications

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

Identification and characterization of a novel 5‐hydroxytryptamine receptor in the sea cucumber Apostichopus japonicus (Selenka)

Comparative Analysis of Tryptophan Dynamics in Spectrin and Its Constituent Domains: Insights from Fluorescence

Intrinsic Dynamics and Causality in Correlated Motions Unraveled in Two Distinct Inactive States of Human β2-Adrenergic Receptor

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Intrinsic Dynamics and Causality in Correlated Motions Unraveled in Two Distinct Inactive States of Human β₂-Adrenergic Receptor