Solution structures of the SH3 domains from Shank scaffold proteins and their interactions with Cav1.3 calcium channels

Abstract

Shank proteins are abundant scaffold proteins in the postsynaptic density (PSD) region of brain synapses. Mutations in Shank proteins are associated with autism, schizophrenia, and Alzheimer's disease. To gain insights into Shank protein interactions at the PSD, we determined the solution structures of the src homology 3 (SH3) domains of all three mammalian Shank proteins. Our findings indicate that they have identical and typical SH3 folding motifs, but unusual target-binding pockets. An investigation into the interaction between the Shank SH3 domains and the proline-rich region of the Cav1.3 calcium channel revealed an atypical interaction in which the highly acidic specificity binding pocket of the SH3 domains binds to a Cav1.3 region containing a cluster of three Arg residues. Our study provides insights into Shank SH3-mediated interactions.

Clustering of CaV1.3 L-type calcium channels by Shank3

“…In contrast to some prior reports, our data provided no indication that the Shank3 SH3 domain plays a significant role in this interaction (Zhang et al, 2005). The reasons for this discrepancy are unclear, but it is possible that a low affinity interaction of CaV1.3L with the SH3 domain (e.g., Ishida et al, 2018) could not be detected under our experimental conditions. These in vitro studies also indicated that β auxiliary subunits had a hitherto unappreciated role in facilitating Shank3 interactions with CaV1.3L LTCCs, apparently by also interacting with Shank3.…”

“…Prior studies indicate that the Shank3 PDZ and SH3 domains interact directly with the C terminal-ITTL motif of Ca V 1.3 L and an adjacent proline-rich region, respectively (Perfitt et al, 2020; Zhang et al, 2005). However, structural studies indicated that the Shank3 SH3 domain is atypical and has only weak (or no) interaction with multiple Ca V 1.3-based proline-rich peptides (Ishida et al, 2018; Ponna et al, 2017). In addition, an N-terminal extension to the Shank3 PDZ domain is critical for high-affinity interactions with GKAP (Zhou et al, 2016).…”

Clustering of CaV1.3 L‐type calcium channels by Shank3

“…In contrast to a prior report (Zhang et al, 2005), our data provided no indication that the Shank3 SH3 domain plays a significant role in this interaction. The reasons for this discrepancy are unclear, but it is possible that a low affinity interaction of Ca V 1.3 L with the SH3 domain (Ishida et al, 2018) could not be detected under our experimental conditions. These in vitro studies also indicated that β auxiliary subunits had a hitherto unappreciated role in facilitating Shank3 interactions with Ca V 1.3 L LTCCs, apparently by also interacting with Shank3.…”

“…Prior studies indicate that the Shank3 PDZ and SH3 domains interact directly with the C terminal‐ITTL motif of Ca V 1.3 L and an adjacent proline‐rich region, respectively (Perfitt et al, 2020; Zhang et al, 2005). However, structural studies indicated that the Shank3 SH3 domain is atypical and has only weak (or no) interaction with multiple Ca V 1.3‐based proline‐rich peptides (Ishida et al, 2018; Ponna et al, 2017). In addition, an N‐terminal extension to the Shank3 PDZ domain is critical for high‐affinity interactions with GKAP (Zhou et al, 2016), but its role in binding Ca V 1.3 is poorly understood.…”

Interactions with PDZ proteins diversify voltage‐gated calcium channel signaling

“…The Lymnaea stagnalis neuron model has also shown that such interaction is required for synaptic activity (Spafford, Chen, Feng, Smit, & Zamponi, 2003). In contrast, the corresponding C-terminal region of Ca V 2.1 is not an essential determinant for its subcellular localization even the PDZ binding motif is also conserved in the long variant of Ca V 2.1 (Hu, Saegusa, Hayashi, & Tanabe, 2005 (Hu et al, 2005). Studies in vitro introduced the concept of presynaptic "slots" to refer to presynaptic binding sites that are specific for channels to regulate their participation in neurotransmission.…”