| Structural highlights
Function
[MICU1_HUMAN] Key regulator of mitochondrial calcium uniporter (MCU) required to limit calcium uptake by MCU when cytoplasmic calcium is low. Acts as a gatekeeper that senses calcium level via its EF-hand domains and sets a threshold for mitochondrial calcium uptake by MCU, thereby preventing mitochondrial calcium overload. Regulates glucose-dependent insulin secretion in pancreatic beta-cells by regulating mitochondrial calcium uptake. Induces T-helper 1-mediated autoreactivity, which is accompanied by the release of IFNG.[1] [2] [3] [4] [MICU2_HUMAN] Key regulator of mitochondrial calcium uniporter (MCU) required to limit calcium uptake by MCU when cytoplasmic calcium is low (PubMed:24503055, PubMed:24560927, PubMed:26903221). MICU1 and MICU2 form a disulfide-linked heterodimer that stimulate and inhibit MCU activity, depending on the concentration of calcium (PubMed:24560927). MICU2 acts as a gatekeeper of MCU that senses calcium level via its EF-hand domains: prevents channel opening at resting calcium, avoiding energy dissipation and cell-death triggering (PubMed:24560927).[5] [6] [7] [8]
Publication Abstract from PubMed
Mitochondrial calcium uptake proteins 1 and 2 (MICU1 and MICU2) mediate mitochondrial Ca(2+) influx via the mitochondrial calcium uniporter (MCU). Its molecular action for Ca(2+) uptake is tightly controlled by the MICU1-MICU2 heterodimer, which comprises Ca(2+) sensing proteins which act as gatekeepers at low [Ca(2+)] or facilitators at high [Ca(2+)]. However, the mechanism underlying the regulation of the Ca(2+) gatekeeping threshold for mitochondrial Ca(2+) uptake through the MCU by the MICU1-MICU2 heterodimer remains unclear. In this study, we determined the crystal structure of the apo form of the human MICU1-MICU2 heterodimer that functions as the MCU gatekeeper. MICU1 and MICU2 assemble in the face-to-face heterodimer with salt bridges and me-thio-nine knobs stabilizing the heterodimer in an apo state. Structural analysis suggests how the heterodimer sets a higher Ca(2+) threshold than the MICU1 homodimer. The structure of the heterodimer in the apo state provides a framework for understanding the gatekeeping role of the MICU1-MICU2 heterodimer.
Structure of the MICU1-MICU2 heterodimer provides insights into the gatekeeping threshold shift.,Park J, Lee Y, Park T, Kang JY, Mun SA, Jin M, Yang J, Eom SH IUCrJ. 2020 Feb 27;7(Pt 2):355-365. doi: 10.1107/S2052252520001840. eCollection, 2020 Mar 1. PMID:32148862[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Perocchi F, Gohil VM, Girgis HS, Bao XR, McCombs JE, Palmer AE, Mootha VK. MICU1 encodes a mitochondrial EF hand protein required for Ca(2+) uptake. Nature. 2010 Sep 16;467(7313):291-6. doi: 10.1038/nature09358. Epub 2010 Aug 8. PMID:20693986 doi:http://dx.doi.org/10.1038/nature09358
- ↑ Mallilankaraman K, Doonan P, Cardenas C, Chandramoorthy HC, Muller M, Miller R, Hoffman NE, Gandhirajan RK, Molgo J, Birnbaum MJ, Rothberg BS, Mak DO, Foskett JK, Madesh M. MICU1 is an essential gatekeeper for MCU-mediated mitochondrial Ca(2+) uptake that regulates cell survival. Cell. 2012 Oct 26;151(3):630-44. doi: 10.1016/j.cell.2012.10.011. PMID:23101630 doi:http://dx.doi.org/10.1016/j.cell.2012.10.011
- ↑ Alam MR, Groschner LN, Parichatikanond W, Kuo L, Bondarenko AI, Rost R, Waldeck-Weiermair M, Malli R, Graier WF. Mitochondrial Ca2+ uptake 1 (MICU1) and mitochondrial ca2+ uniporter (MCU) contribute to metabolism-secretion coupling in clonal pancreatic beta-cells. J Biol Chem. 2012 Oct 5;287(41):34445-54. doi: 10.1074/jbc.M112.392084. Epub 2012, Aug 17. PMID:22904319 doi:http://dx.doi.org/10.1074/jbc.M112.392084
- ↑ Kamer KJ, Mootha VK. MICU1 and MICU2 play nonredundant roles in the regulation of the mitochondrial calcium uniporter. EMBO Rep. 2014 Mar;15(3):299-307. doi: 10.1002/embr.201337946. Epub 2014 Feb 6. PMID:24503055 doi:http://dx.doi.org/10.1002/embr.201337946
- ↑ Patron M, Checchetto V, Raffaello A, Teardo E, Vecellio Reane D, Mantoan M, Granatiero V, Szabo I, De Stefani D, Rizzuto R. MICU1 and MICU2 finely tune the mitochondrial Ca2+ uniporter by exerting opposite effects on MCU activity. Mol Cell. 2014 Mar 6;53(5):726-37. doi: 10.1016/j.molcel.2014.01.013. Epub 2014, Feb 20. PMID:24560927 doi:http://dx.doi.org/10.1016/j.molcel.2014.01.013
- ↑ Petrungaro C, Zimmermann KM, Kuttner V, Fischer M, Dengjel J, Bogeski I, Riemer J. The Ca(2+)-Dependent Release of the Mia40-Induced MICU1-MICU2 Dimer from MCU Regulates Mitochondrial Ca(2+) Uptake. Cell Metab. 2015 Oct 6;22(4):721-33. doi: 10.1016/j.cmet.2015.08.019. Epub 2015, Sep 17. PMID:26387864 doi:http://dx.doi.org/10.1016/j.cmet.2015.08.019
- ↑ Matesanz-Isabel J, Arias-del-Val J, Alvarez-Illera P, Fonteriz RI, Montero M, Alvarez J. Functional roles of MICU1 and MICU2 in mitochondrial Ca(2+) uptake. Biochim Biophys Acta. 2016 Jun;1858(6):1110-7. doi: 10.1016/j.bbamem.2016.02.022., Epub 2016 Feb 18. PMID:26903221 doi:http://dx.doi.org/10.1016/j.bbamem.2016.02.022
- ↑ Park J, Lee Y, Park T, Kang JY, Mun SA, Jin M, Yang J, Eom SH. Structure of the MICU1-MICU2 heterodimer provides insights into the gatekeeping threshold shift. IUCrJ. 2020 Feb 27;7(Pt 2):355-365. doi: 10.1107/S2052252520001840. eCollection, 2020 Mar 1. PMID:32148862 doi:http://dx.doi.org/10.1107/S2052252520001840
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