Supplementary Information. Coupling ion channels to receptors for biomolecule sensing

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1 Supplementary Information Coupling ion channels to receptors for iomolecule sensing CHRISTOPHE J. MOREAU 1#, JULIEN P. DUPUIS 1, JEAN REVILLOUD 1, KARTHIK ARUMUGAM 2 AND MICHEL VIVAUDOU 1* 1 Institut de Biologie Structurale (CEA, CNRS, UJF), Laoratoire des Protéines Memranaires, 1 rue Jules Horowitz, 3827 Grenole, France 2 Institut de Recherches en Technologies et Sciences pour le Vivant, Laoratoire Chimie et Biologie des Métaux, CEA/Grenole, 17 rue des Martyrs, 381 Grenole, France * vivaudou@cea.fr # christophe.moreau@is.fr SUPPLEMENTARY METHODS MOLECULAR MODELING M2 was modeled y homology (program Modeller 9v1 [REF 1]) using the crystallographic structure of a chimeric β2- adrenergic receptor/t-lysozyme (PDB code 2RH1) 2. Kir6.2 was modeled from a 3D structural alignment with the structures of a KirBac1.3/Kir3.1 chimera (PDB code 1N9P) 3, and of the cytoplasmic regions of Kir2.1 (PDB code 2GIX) and Kir3.1 (PDB code IN9P). It was not possile to predict with any accuracy the relative positions of Kir6.2 and M2 in the M2-K fusion protein. The orientations of M2 and of the M2-Kir6.2 linker in Fig. 2 remain therefore aritrary. The representations in Fig. 2 of the stretches linking H8 to ß1 and ß1 to the Kir6.2 slide helix are also aritrary ecause no high resolution structural data are availale or predictale for these regions. 1. Sali, A. & Blundell, T. L. Comparative protein modelling y satisfaction of spatial restraints. J. Mol. Biol. 23, (1993). 2. Cherezov, V. et al. High-resolution crystal structure of an engineered human ß2-adrenergic G protein-coupled receptor. Science 318, (27). 3. Nishida, M., Cadene, M., Chait, B. T. & MacKinnon, R. Crystal structure of a Kir3.1-prokaryotic Kir channel chimera. EMBO J. 26, -1 (27).. Pegan, S., Arrait, C., Slesinger, P. A. & Choe, S. Andersen's syndrome mutation effects on the structure and assemly of the cytoplasmic domains of Kir2.1. Biochemistry, (26).. Nishida, M. & Mackinnon, R. Structural asis of inward rectification: Cytoplasmic pore of the G protein-gated inward rectifier GIRK1 at 1.8 angstrom resolution. Cell 111, (22) Macmillan Pulishers Limited. All rights reserved.

2 SUPPLEMENTARY FIGURES a M2-K M2-K + Kir3. * Ba 2+ M2-K-3 na 6 s c d M2-K-3 +Kir3. * Ba 2+ 6 s e % change induced y µm * 1 na 3 s µa 6 s M2-K M2-K + Kir3. * M2-K-3 M2-K-3 + Kir3. * f Out M2 Kir6.2 g Kir3. * M2 Kir6.2 Cyto Gβγ Gα Supplementary Figure 1 The M2 receptor remains functional when fused with Kir6.2. a,, Whole-cell current records from oocytes expressing M2-K or M2-K-3. These constructs are not significantly modulated y µm. c, d, Same experiment as in panels a and except that M2-K or M2-K-3 are co-expressed with the G-protein activated K + channel Kir3. *. e, Changes in whole-cell current evoked y. Values in the presence of Kir3. * were significantly different from those in its asence (* P<.1 and P<.1). f, g, Interpretation of the experimental results of aove panels: inding to M2-K or M2-K-3 induces a conformational change in M2 that triggers G- protein activation as evidenced y opening of Kir3. * ut this change is not transmitted to Kir6.2 ecause of an inappropriate linker. The findings that M2 is fully functional in M2-K and M2-K-3 suggest that this is also the case for the intermediate constructs M2-K-2 and M2-K-2. In these latter constructs, the fused Kir6.2 is activated directly y. Because direct Kir6.2 activation and indirect Kir3. * activation are comparale and could e difficult to dissociate, the responsive M2 constructs were not assayed with Kir3. *. In contrast, the responsive D2-K-2 could e assayed with Kir3. * with little risk of confusion ecause D2-K-2 expression levels were lower than that of Kir3. * (Fig. ) Macmillan Pulishers Limited. All rights reserved.

3 a Atropine Ba 2+ 2 Atropine M2 + KΔ M2-K-2 1 na 3 s 3 na 3 s % change in current M2 + KΔ 9 1 * * M2-K-2 M2-K-2 7 M2-K-3 M2-K-2 na 6 s Supplementary Figure 2 Effects of the antagonist atropine on M2-ased ICCRs. a, TEVC recordings of coexpressed M2 receptor and KΔ (negative control), and -sensitive ICCRs (M2-K-2 and M2-K-2). Atropine (1 µm) reversily locks activation y µm of M2-K-2 and M2-K-2., Changes in whole-cell currents elicited y µm efore (lue), during (red) and after (lue) application of 1 µm atropine to the specified constructs. Values in atropine were significantly less than without, where indicated (* P<.1) Macmillan Pulishers Limited. All rights reserved.

4 a Ba * M2 + Kir3. * M2 + Kir3. * + PTX 3 s 6 s % change induced y µm PTX + PTX + PTX M2 + Kir3. * M2-K-2 M2-K-2 M2-K-2 3 s 3 na M2-K-2 + PTX 6 s na Supplementary Figure 3 ICCR activation is G-protein independent. a, Whole-cell current responses to µm of oocytes expressing M2 with Kir3. * or M2-K-2 alone, in asence or presence of the co-expressed catalytic domain S1 of PTX. PTX suppresses the activation of Kir3. * ut not that of the muscarinic ICCR., Average change in current evoked y for the experiments illustrated in panel a. The antagonistic effect of PTX was significant for M2+Kir3. * (* P<.) ut not M2-K constructs ( P>.2). 28 Macmillan Pulishers Limited. All rights reserved.

5 D2-K-2 D2 + KΔ a % inhiition % inhiition nm 1 µm [Dopamine] 1 µm 1 nm 1 nm 1 µm [Quinpirole] 1 mm Supplementary Figure Inhiition of D2 ICCR at high concentrations of the agonists dopamine and quinpirole is partly due to a direct effect on Kir6.2. We measured the inhiition of whole-cell currents from oocytes expressing D2-K-2 (triangles) or D2 + KΔ (squares) y increasing concentrations of dopamine (a) or quinpirole (). The inhiition of D2-K-2 y dopamine reached saturation at ~ µm efore any sizale effect on D2 + KΔ could e detected. In contrast, µm quinpirole locked D2 + KΔ y ~1% in qualitative agreement with the previously-descried lock y quinpirole of native Kir6.2-containing KATP channels [Yang et al., Br. J. Pharmacol. 13, 96 (2)]. At higher concentrations, lock of D2 + KΔ was too prominent to relialy quantify any additional D2- mediated effect on D2-K-2. Assuming full lockade at high concentrations, quinpirole lock could e modelled y a Hill equation with EC=39 µm and h=1.2 (solid line). To account for D2 + KΔ lock, the data presented in Figure 3 were corrected y sutracting the D2 + KΔ inhiition from that of D2-K Macmillan Pulishers Limited. All rights reserved.