Ancient association between cation leak channels and Mid1 proteins is conserved in fungi and animals

Abstract

Neuronal resting potential can tune the excitability of neural networks, affecting downstream behavior. Sodium leak channels (NALCN) play a key role in rhythmic behaviors by helping set, or subtly changing neuronal resting potential. The full complexity of these newly described channels is just beginning to be appreciated, however. NALCN channels can associate with numerous subunits in different tissues and can be activated by several different peptides and second messengers. We recently showed that NALCN channels are closely related to fungal calcium channels, which they functionally resemble. Here, we use this relationship to predict a family of NALCN-associated proteins in animals on the basis of homology with the yeast protein Mid1, the subunit of the yeast calcium channel. These proteins all share a cysteine-rich region that is necessary for Mid1 function in yeast. We validate this predicted association by showing that the Mid1 homolog in Drosophila, encoded by the CG33988 gene, is coordinately expressed with NALCN, and that knockdown of either protein creates identical phenotypes in several behaviors associated with NALCN function. The relationship between Mid1 and leak channels has therefore persisted over a billion years of evolution, despite drastic changes to both proteins and the organisms in which they exist.

A Conserved Bicycle Model for Circadian Clock Control of Membrane Excitability

“…In contrast to the previously reported weak effect of CG33988 RNAi knockdown on evening behavior (Ghezzi et al, 2014), we found dramatic reductions in rhythmic strength in DD (3/3 lines) and reduced anticipation of lights-on (2/3 lines) and lights-off transitions (3/3 lines) under LD conditions (Fig. 6A, Fig.…”

The Cch1-Mid1 High-Affinity Calcium Channel Contributes to the Virulence of Cryptococcus neoformans by Mitigating Oxidative Stress

“…Taken together, these results suggested that the C 648 P 649 dipeptide (CP 1 ) was likely crucial to the overall folding and structure of the Mid1 polypeptide, since its substitution produced a strain with a phenotype similar to that of the strain lacking Mid1 (mid1⌬ null strain) in limited extracellular [Ca 2ϩ ]. This is consistent with a recent report that demonstrated that C 648 is required for Mid1 function in Saccharomyces cerevisiae (27).…”

“…Despite the high level of conservation of both CP dipeptides across fungal species, amino acid substitution analysis revealed that the loss of the second CP dipeptide had no effect on H 2 O 2 stress response in C. neoformans. We could not assess the role of the first CP dipeptide, since this cysteine residue was critical for Mid1 functional activity, consistent with a previous finding (27).…”

“…We and others showed previously that Mid1 has 12 highly conserved cysteine residues near its C-terminal region, several of which are required for the functional activity of Mid1 (8). The two cysteine residues within the CP dipeptides belong to this group of 12 previously reported cysteines (27).…”

Coupling of a voltage‐gated Ca2+ channel homologue with a plasma membrane H+‐ATPase in yeast

“…Recent studies have shown that the Cch1/Mid1 channel subfamily is more closely related to a newly found subfamily of VGCCs, sodium leak channels or NALCNs (Na + leak channels nonselective). Structural and functional similarities between the Cch1/Mid1 channel and NALCNs are seen in some criteria, including the primary sequences of the Cch1/a 1 subunits, insensitivity to voltage and the complete dependency on the Mid1 subunit or its animal functional equivalents (Liebeskind et al 2012;Ghezzi et al 2014).…”