6533b861fe1ef96bd12c57c6

RESEARCH PRODUCT

Structure of the Human TRPML2 Ion Channel Extracytosolic/Lumenal Domain.

Annika WagnerAnnika WagnerNina MorgnerNicole BaderKerstin K. VietKerstin K. VietHermann SchindelinMartha BrennichTanja SchirmeisterKevin SchwickertNils HellwigUte A. HellmichUte A. Hellmich

subject

Models Molecular0303 health sciencesBinding SitesTRPMLEndosomeChemistrySmall-angle X-ray scatteringProtein Conformation030302 biochemistry & molecular biologyIsothermal titration calorimetryHydrogen-Ion ConcentrationCrystallography X-Ray03 medical and health sciencesTransient receptor potential channelTransmembrane domainTransient Receptor Potential ChannelsProtein DomainsStructural BiologyBiophysicsHumansCalciumMolecular BiologyProtein secondary structureIon channel030304 developmental biology

description

Summary TRPML2 is the least structurally characterized mammalian transient receptor potential mucolipin ion channel. The TRPML family hallmark is a large extracytosolic/lumenal domain (ELD) between transmembrane helices S1 and S2. We present crystal structures of the tetrameric human TRPML2 ELD at pH 6.5 (2.0 A) and 4.5 (2.95 A), corresponding to the pH values in recycling endosomes and lysosomes. Isothermal titration calorimetry shows Ca2+ binding to the highly acidic central pre-pore loop which is abrogated at low pH, in line with a pH-dependent channel regulation model. Small angle X-ray scattering confirms the ELD dimensions in solution. Changes in pH or Ca2+ concentration do not affect the protein's secondary structure, but can influence ELD oligomer integrity according to native mass spectrometry. Our data thus complete the set of high-resolution views of human TRPML channel ELDs and reveal some structural responses to the conditions the TRPML2 ELD encounters as the channel traffics through the endolysosomal system.

yearjournalcountryeditionlanguage
2019-08-01Structure (London, England : 1993)
10.1016/j.str.2019.04.016https://pubmed.ncbi.nlm.nih.gov/31178222