Structural basis of calcineurin activation by calmodulin

Ye, Qilu; Feng, Yedan; Yin, Yi‐Chen; Faucher, Frédérick; Currie, Mark A.; Rahman, Mona N.; Jin, Jin; Li, Shanze; Wang, Qun; Jia, Zongchao

doi:10.1016/j.cellsig.2013.08.033

Cited by 27 publications

(33 citation statements)

References 63 publications

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“…Our model is akin to the classical activation mechanism whereby an autoinhibitory interaction is disrupted by the binding of diffusible Ca 2+ -CaM to activate many enzymes (17,18) and some channels (19,20). This model is similar to that proposed by Strotmann et al (10), where the CBD itself binds an N-terminal region (S117-S134) in the absence of CaM.…”

Section: Discussionsupporting

confidence: 51%

A channelopathy mechanism revealed by direct calmodulin activation of TrpV4

Loukin

Teng

Kung

2015

Proc. Natl. Acad. Sci. U.S.A.

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Ca 2+ -calmodulin (CaM) regulates varieties of ion channels, including Transient Receptor Potential vanilloid subtype 4 (TrpV4). It has previously been proposed that internal Ca 2+ increases TrpV4 activity through Ca 2+ -CaM binding to a C-terminal Ca 2+ -CaM binding domain (CBD). We confirmed this model by directly presenting Ca 2+ -CaM protein to membrane patches excised from TrpV4-expressing oocytes. Over 50 TRPV4 mutations are now known to cause heritable skeletal dysplasia (SD) and other diseases in human. We have previously examined 14 SD alleles and found them to all have gain-of-function effects, with the gain of constitutive open probability paralleling disease severity. Among the 14 SD alleles examined, E797K and P799L are located immediate upstream of the CBD. They not only have increase basal activity, but, unlike the wild-type or other SD-mutant channels examined, they were greatly reduced in their response to Ca 2+ -CaM. Deleting a 10-residue upstream peptide (Δ795-804) that covers the two SD mutant sites resulted in strong constitutive activity and the complete lack of Ca 2+ -CaM response. We propose that the region immediately upstream of CBD is an autoinhibitory domain that maintains the closed state through electrostatic interactions, and adjacent detachable Ca 2+ -CaM binding to CBD sterically interferes with this autoinhibition. This work further supports the notion that TrpV4 mutations cause SD by constitutive leakage. However, the closed conformation is likely destabilized by various mutations by different mechanisms, including the permanent removal of an autoinhibition documented here.skeletal dysplasia | calcium | ion channel | autoinhibition | TrpV1

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Section: Discussionsupporting

confidence: 51%

A channelopathy mechanism revealed by direct calmodulin activation of TrpV4

Loukin

Teng

Kung

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…A recent paper also claimed to present the crystal structure of a protein-protein complex for CaM-calcineurin, but unfortunately, the entire CaM molecule, as well as its target region, was invisible in the crystal (Ye et al 2013). This is especially surprising, since CaM was elsewhere shown to induce folding of the calcineurin regulatory domain also outside the CaM-binding site (Rumi-Masante et al 2012).…”

mentioning

confidence: 87%

The many structural faces of calmodulin: a multitasking molecular jackknife

Kursula

2014

Amino Acids

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Calmodulin (CaM) is a highly conserved protein and a crucial calcium sensor in eukaryotes. CaM is a regulator of hundreds of diverse target proteins. A wealth of studies has been carried out on the structure of CaM, both in the unliganded form and in complexes with target proteins and peptides. The outcome of these studies points toward a high propensity to attain various conformational states, depending on the binding partner. The purpose of this review is to provide examples of different conformations of CaM trapped in the crystal state. In addition, comparisons are made to corresponding studies in solution. The different CaM conformations in crystal structures are also compared based on the positions of the metal ions bound to their EF hands, in terms of distances, angles, and pseudo-torsion angles. Possible caveats and artifacts in CaM crystal structures are discussed, as well as the possibilities of trapping biologically relevant CaM conformations in the crystal state.

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“…Therefore, how the other autoinhibitory elements in CNA-RD exert their autoinhibitory effects remains elusive. Recently, Ye et al [16] reported a crystal structure of CN covalently linked to CaM (PDB ID code: 4IL1), which retains full CaM-activated activity. Surprisingly, the crystal structure showed virtually no structural change in the active site and no evidence of CaM despite being covalently linked.…”

Section: Introductionmentioning

confidence: 99%

Cooperative autoinhibition and multi-level activation mechanisms of calcineurin

Wang

et al. 2016

Cell Res

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The Ca 2+ /calmodulin-dependent protein phosphatase calcineurin (CN), a heterodimer composed of a catalytic subunit A and an essential regulatory subunit B, plays critical functions in various cellular processes such as cardiac hypertrophy and T cell activation. It is the target of the most widely used immunosuppressants for transplantation, tacrolimus (FK506) and cyclosporin A. However, the structure of a large part of the CNA regulatory region remains to be determined, and there has been considerable debate concerning the regulation of CN activity. Here, we report the crystal structure of full-length CN (β isoform), which revealed a novel autoinhibitory segment (AIS) in addition to the well-known autoinhibitory domain (AID). The AIS nestles in a hydrophobic intersubunit groove, which overlaps the recognition site for substrates and immunosuppressant-immunophilin complexes. Indeed, disruption of this AIS interaction results in partial stimulation of CN activity. More importantly, our biochemical studies demonstrate that calmodulin does not remove AID from the active site, but only regulates the orientation of AID with respect to the catalytic core, causing incomplete activation of CN. Our findings challenge the current model for CN activation, and provide a better understanding of molecular mechanisms of CN activity regulation.

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Structural basis of calcineurin activation by calmodulin

Cited by 27 publications

References 63 publications

A channelopathy mechanism revealed by direct calmodulin activation of TrpV4

A channelopathy mechanism revealed by direct calmodulin activation of TrpV4

The many structural faces of calmodulin: a multitasking molecular jackknife

Cooperative autoinhibition and multi-level activation mechanisms of calcineurin

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