The calmodulin-binding, short linear motif, NSCaTE is conserved in L-type channel ancestors of vertebrate Cav1.2 and Cav1.3 channels

PLoS One. 2013 Apr 23;8(4):e61765. doi: 10.1371/journal.pone.0061765. Print 2013.

Abstract

NSCaTE is a short linear motif of (xWxxx(I or L)xxxx), composed of residues with a high helix-forming propensity within a mostly disordered N-terminus that is conserved in L-type calcium channels from protostome invertebrates to humans. NSCaTE is an optional, lower affinity and calcium-sensitive binding site for calmodulin (CaM) which competes for CaM binding with a more ancient, C-terminal IQ domain on L-type channels. CaM bound to N- and C- terminal tails serve as dual detectors to changing intracellular Ca(2+) concentrations, promoting calcium-dependent inactivation of L-type calcium channels. NSCaTE is absent in some arthropod species, and is also lacking in vertebrate L-type isoforms, Cav1.1 and Cav1.4 channels. The pervasiveness of a methionine just downstream from NSCaTE suggests that L-type channels could generate alternative N-termini lacking NSCaTE through the choice of translational start sites. Long N-terminus with an NSCaTE motif in L-type calcium channel homolog LCav1 from pond snail Lymnaea stagnalis has a faster calcium-dependent inactivation than a shortened N-termini lacking NSCaTE. NSCaTE effects are present in low concentrations of internal buffer (0.5 mM EGTA), but disappears in high buffer conditions (10 mM EGTA). Snail and mammalian NSCaTE have an alpha-helical propensity upon binding Ca(2+)-CaM and can saturate both CaM N-terminal and C-terminal domains in the absence of a competing IQ motif. NSCaTE evolved in ancestors of the first animals with internal organs for promoting a more rapid, calcium-sensitive inactivation of L-type channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Binding Sites
  • Biological Evolution
  • Calcium Channels, L-Type / chemistry*
  • Calcium Channels, L-Type / classification
  • Calcium Channels, L-Type / genetics
  • Calcium Channels, L-Type / metabolism
  • Calmodulin / chemistry
  • Calmodulin / genetics
  • Calmodulin / metabolism*
  • Conserved Sequence
  • Gene Expression
  • Genes, Reporter
  • Green Fluorescent Proteins
  • HEK293 Cells
  • Humans
  • Molecular Sequence Data
  • Patch-Clamp Techniques
  • Phylogeny
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Sequence Homology, Amino Acid
  • Snails / genetics
  • Snails / metabolism*

Substances

  • Calcium Channels, L-Type
  • Calmodulin
  • L-type calcium channel alpha(1C)
  • alpha1D (Cav1.3) L-type calcium channel, human
  • Green Fluorescent Proteins

Grant support

This work was supported by Heart and Stroke Foundation of Canada, Grant-in-Aid to JDS, and Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Operating grants to JDS and JGG. VT received support from an NSERC Canadian Graduate Scholarship Doctoral Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.