title: Structural and dynamic insights into the subtype-specific IP3-binding mechanism of the IP3 receptor.
abstract: There are three subtypes of vertebrate inositol 1,4,5-trisphosphate (IP3) receptor (IP3R), a Ca2+-release channel on the ER membrane - IP3R1, IP3R2, and IP3R3 - each of which has a distinctive role in disease development. To determine the subtype-specific IP3-binding mechanism, we compared the thermodynamics, thermal stability, and conformational dynamics between the N-terminal regions of IP3R1 (IP3R1-NT) and IP3R3 (IP3R3-NT) by performing circular dichroism (CD), isothermal titration calorimetry (ITC), and hydrogen-deuterium exchange mass spectrometry (HDX-MS). Previously determined crystal structures of IP3R1-NT and HDX-MS results from this study revealed that both IP3R1 and IP3R3 adopt a similar IP3-binding mechanism. However, several regions, including the α- and β-interfaces, of IP3R1-NT and IP3R3-NT show significantly different conformational dynamics upon IP3binding, which may explain the different IP3-binding affinities between the subtypes. The importance of the interfaces for subtype-specific IP3binding is also supported by the different dynamic conformations of the two subtypes in the apo-states. Furthermore, IP3R1-NT and IP3R3-NT show different IP3-binding affinities and thermal stabilities, but share similar thermodynamic properties for IP3binding. These results collectively provide new insights into the mechanism underlying IP3binding to IP3Rs and the subtype-specific regulatory mechanism.
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea.
authors.forename: Su Youn
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea Institute of Pharmaceutical Science and Technology, College of Pharmacy, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea.
authors.forename: Hee-Seop
authors.initials: HS
authors.lastname: Yoo
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea Institute of Pharmaceutical Science and Technology, College of Pharmacy, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea.
authors.forename: Hye-Seung
authors.initials: HS
authors.lastname: Choi
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea.
authors.forename: Ka Young
authors.initials: KY
authors.lastname: Chung
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea Institute of Pharmaceutical Science and Technology, College of Pharmacy, Ajou University, Suwon, Gyeonggi 16499, Republic of Korea.
authors.forename: Min-Duk
authors.initials: MD
authors.lastname: Seo
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D051379:Mice; D008954:Models, Biological; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013816:Thermodynamics
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D015544:Inositol 1,4,5-Trisphosphate
keywords: IP3 binding; IP3 receptor; conformational dynamics; hydrogen-deuterium exchange mass spectroscopy; thermal stability; thermodynamics