scholarly journals Functional basis for calmodulation of the TRPV5 calcium channel

2021 ◽  
Author(s):  
Sara R Roig ◽  
Niky Thijssen ◽  
Merijn van Erp ◽  
Jack Fransen ◽  
Joost G Hoenderop ◽  
...  
Keyword(s):  
Single Molecule ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Feedback Mechanism ◽  
Negative Feedback Mechanism ◽  
Biochemical Assays ◽  
Selective Channel ◽  
Cam Regulation ◽  
Transient Receptor ◽  
Microscopy Techniques

AbstractWithin the transient receptor potential (TRP) superfamily of ion channels, TRPV5 is a highly Ca2+-selective channel important for active reabsorption of Ca2+ in the kidney. Its channel activity is controlled by a negative feedback mechanism involving calmodulin (CaM) binding. Combining advanced microscopy techniques and biochemical assays, this study characterized the dynamic bilobal CaM regulation and binding stoichiometry. We demonstrate for the first time that functional (full-length) TRPV5 interacts with CaM in the absence of Ca2+, and this interaction is intensified at increasing Ca2+ concentrations sensed by the CaM C-lobe that achieves channel pore blocking. Channel inactivation occurs without CaM N-lobe calcification. Moreover, we reveal a 1:2 stoichiometry of TRPV5:CaM binding by implementing single molecule photobleaching counting, a technique with great potential for studying TRP channel regulation. In conclusion, our study proposes a new model for CaM- dependent regulation – calmodulation – of the Ca2+-selective TRPV5 that involves apoCaM interaction and lobe-specific actions.

scholarly journals Distinct properties of Ca2+–calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel

2012 ◽  
Vol 140 (5) ◽  
pp. 541-555 ◽  
Author(s):  
Sze-Yi Lau ◽  
Erik Procko ◽  
Rachelle Gaudet
Keyword(s):  
Binding Site ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Feedback Mechanism ◽  
Sequence Motif ◽  
Recognition Sequence ◽  
Calmodulin Binding ◽  
Negative Feedback Mechanism ◽  
C Terminus ◽  
Wide Range

Transient receptor potential (TRP) vanilloid 1 (TRPV1) is a molecular pain receptor belonging to the TRP superfamily of nonselective cation channels. As a polymodal receptor, TRPV1 responds to heat and a wide range of chemical stimuli. The influx of calcium after channel activation serves as a negative feedback mechanism leading to TRPV1 desensitization. The cellular calcium sensor calmodulin (CaM) likely participates in the desensitization of TRPV1. Two CaM-binding sites are identified in TRPV1: the N-terminal ankyrin repeat domain (ARD) and a short distal C-terminal (CT) segment. Here, we present the crystal structure of calcium-bound CaM (Ca2+–CaM) in complex with the TRPV1-CT segment, determined to 1.95-Å resolution. The two lobes of Ca2+–CaM wrap around a helical TRPV1-CT segment in an antiparallel orientation, and two hydrophobic anchors, W787 and L796, contact the C-lobe and N-lobe of Ca2+–CaM, respectively. This structure is similar to canonical Ca2+–CaM-peptide complexes, although TRPV1 contains no classical CaM recognition sequence motif. Using structural and mutational studies, we established the TRPV1 C terminus as a high affinity Ca2+–CaM-binding site in both the isolated TRPV1 C terminus and in full-length TRPV1. Although a ternary complex of CaM, TRPV1-ARD, and TRPV1-CT had previously been postulated, we found no biochemical evidence of such a complex. In electrophysiology studies, mutation of the Ca2+–CaM-binding site on TRPV1-ARD abolished desensitization in response to repeated application of capsaicin, whereas mutation of the Ca2+–CaM-binding site in TRPV1-CT led to a more subtle phenotype of slowed and reduced TRPV1 desensitization. In summary, our results show that the TRPV1-ARD is an important mediator of TRPV1 desensitization, whereas TRPV1-CT has higher affinity for CaM and is likely involved in separate regulatory mechanisms.

scholarly journals Acute interactions between intestinal sugar and calcium transport in vitro

2014 ◽  
Vol 306 (1) ◽  
pp. G1-G12 ◽  
Author(s):  
Phuntila Tharabenjasin ◽  
Veronique Douard ◽  
Chirag Patel ◽  
Nateetip Krishnamra ◽  
Richard J. Johnson ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Glucose Transporter ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Wild Type ◽  
Fructose Metabolism ◽  
Voltage Dependent ◽  
Selective Channel ◽  
Transient Receptor

Fructose consumption by Americans has increased markedly, whereas Ca2+ intake has decreased below recommended levels. Because fructose metabolism decreases enterocyte ATP concentrations, we tested the hypothesis that luminal fructose acutely reduces active, diet-inducible Ca2+ transport in the small intestine. We confirmed that the decrease in ATP concentrations was indeed greater in fructose- compared with glucose-incubated mucosal homogenates from wild-type and was prevented in fructose-incubated homogenates from ketohexokinase (KHK)−/− mice. We then induced active Ca2+ transport by chronically feeding wild-type, fructose transporter glucose transporter 5 (GLUT5)−/−, as well as KHK−/− mice a low Ca2+ diet and measured transepithelial Ca2+ transport in everted duodenal sacs incubated in solutions containing glucose, fructose, or their nonmetabolizable analogs. The diet-induced increase in active Ca2+ transport was proportional to dramatic increases in expression of the Ca2+-selective channel transient receptor potential vanilloid family calcium channel 6 as well as of the Ca2+-binding protein 9k (CaBP9k) but not that of the voltage-dependent L-type channel Ca(v)1.3. Crypt-villus distribution of CaBP9k seems heterogeneous, but low Ca2+ diets induce expression in more cells. In contrast, KHK distribution is homogeneous, suggesting that fructose metabolism can occur in all enterocytes. Diet-induced Ca2+ transport was not enhanced by addition of the enterocyte fuel glutamine and was always greater in sacs of wild-type, GLUT5−/−, and KHK−/− mice incubated with fructose or nonmetabolizable sugars than those incubated with glucose. Thus duodenal Ca2+ transport is not affected by fructose and enterocyte ATP concentrations but instead may decrease with glucose metabolism, as Ca2+ transport remains high with 3- O-methylglucose that is also transported by sodium-glucose cotransporter 1 but cannot be metabolized.

Inositol lipids and TRPC channel activation

2007 ◽  
Vol 74 ◽  
pp. 37-45 ◽  
Author(s):  
James W. Putney
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
Transient Receptor Potential ◽  
Calcium Signalling ◽  
Receptor Potential ◽  
Breakdown Product ◽  
Channel Activation ◽  
Inositol Lipids ◽  
Transient Receptor ◽  
Secondary Mechanism

The original hypothesis put forth by Bob Michell in his seminal 1975 review held that inositol lipid breakdown was involved in the activation of plasma membrane calcium channels or ‘gates’. Subsequently, it was demonstrated that while the interposition of inositol lipid breakdown upstream of calcium signalling was correct, it was predominantly the release of Ca2+ that was activated, through the formation of Ins(1,4,5)P3. Ca2+ entry across the plasma membrane involved a secondary mechanism signalled in an unknown manner by depletion of intracellular Ca2+ stores. In recent years, however, additional non-store-operated mechanisms for Ca2+ entry have emerged. In many instances, these pathways involve homologues of the Drosophila trp (transient receptor potential) gene. In mammalian systems there are seven members of the TRP superfamily, designated TRPC1–TRPC7, which appear to be reasonably close structural and functional homologues of Drosophila TRP. Although these channels can sometimes function as store-operated channels, in the majority of instances they function as channels more directly linked to phospholipase C activity. Three members of this family, TRPC3, 6 and 7, are activated by the phosphoinositide breakdown product, diacylglycerol. Two others, TRPC4 and 5, are also activated as a consequence of phospholipase C activity, although the precise substrate or product molecules involved are still unclear. Thus the TRPCs represent a family of ion channels that are directly activated by inositol lipid breakdown, confirming Bob Michell's original prediction 30 years ago.

Microbe Engineering of Guaia-6,10(14)-diene as a Building Block for the Semisynthetic Production of Plant-Derived (−)-Englerin A

2019 ◽  
Author(s):  
Thomas Siemon ◽  
Zhangqian Wang ◽  
Guangkai Bian ◽  
Tobias Seitz ◽  
Ziling Ye ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Synthetic Biology ◽  
Chemical Synthesis ◽  
Building Block ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Economical Method ◽  
Englerin A ◽  
Transient Receptor

Herein, we report the semisynthetic production of the potent transient receptor potential canonical (TRPC) channel agonist (−)-englerin A (EA), using guaia-6,10(14)-diene as the starting material. Guaia-6,10(14)-diene was systematically engineered in Escherichia coli and Saccharomyces cerevisiae using the CRISPR/Cas9 system and produced with high titers. This provided us the opportunity to execute a concise chemical synthesis of EA and the two related guaianes (−)-oxyphyllol and (+)-orientalol E. The potentially scalable approach combines the advantages of synthetic biology and chemical synthesis and provides an efficient and economical method for producing EA as well as its analogs.

Microbe Engineering of Guaia-6,10(14)-diene as a Building Block for the Semisynthetic Production of Plant-Derived (−)-Englerin A

2019 ◽  
Author(s):  
Thomas Siemon ◽  
Zhangqian Wang ◽  
Guangkai Bian ◽  
Tobias Seitz ◽  
Ziling Ye ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Synthetic Biology ◽  
Chemical Synthesis ◽  
Building Block ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Economical Method ◽  
Englerin A ◽  
Transient Receptor

Herein, we report the semisynthetic production of the potent transient receptor potential canonical (TRPC) channel agonist (−)-englerin A (EA), using guaia-6,10(14)-diene as the starting material. Guaia-6,10(14)-diene was systematically engineered in Escherichia coli and Saccharomyces cerevisiae using the CRISPR/Cas9 system and produced with high titers. This provided us the opportunity to execute a concise chemical synthesis of EA and the two related guaianes (−)-oxyphyllol and (+)-orientalol E. The potentially scalable approach combines the advantages of synthetic biology and chemical synthesis and provides an efficient and economical method for producing EA as well as its analogs.

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