The structural basis of lipid scrambling and inactivation in the endoplasmic reticulum scramblase TMEM16K

Bushell, S.R.; Pike, A.C.W.; Falzone, Maria; Njg., Rorsman; Ta, Chau My; Corey, Robin A.; Newport, Thomas D.; Christianson, John C.; Scofano, Lara F.; Shintre, C.A.; Tessitore, A.; Chu, Amy; Wang, Q; Shrestha, L.; Mukhopadhyay, Shubhashish M.M.; Love, J.; Burgess-Brown, N.; Sitsapesan, Rebecca; Stansfeld, Phillip J.; Huiskonen, Juha T.; Tammaro, Paolo; Accardi, Alessio; Carpenter, E.P.

doi:10.1038/s41467-019-11753-1

Cited by 135 publications

(179 citation statements)

References 75 publications

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“…stably anchoring and/or promoting oligomerization an integral protein within a bilayer [1,2], or targeting a peripheral protein to the surface of a specific cellular membrane. Other interactions influence the function of the protein, either allosterically [3][4][5][6] or via a direct functional role [7,8]. The nature of these lipid interactions is, therefore, the subject of both experimental and computational analyses [6].…”

Section: Protein-lipid Interactions: Structures and Simulationsmentioning

confidence: 99%

The energetics of protein–lipid interactions as viewed by molecular simulations

Corey

Stansfeld

Sansom

2019

Biochemical Society Transactions

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Membranes are formed from a bilayer containing diverse lipid species with which membrane proteins interact. Integral, membrane proteins are embedded in this bilayer, where they interact with lipids from their surroundings, whilst peripheral membrane proteins bind to lipids at the surface of membranes. Lipid interactions can influence the function of membrane proteins, either directly or allosterically. Both experimental (structural) and computational approaches can reveal lipid binding sites on membrane proteins. It is, therefore, important to understand the free energies of these interactions. This affords a more complete view of the engagement of a particular protein with the biological membrane surrounding it. Here, we describe many computational approaches currently in use for this purpose, including recent advances using both free energy and unbiased simulation methods. In particular, we focus on interactions of integral membrane proteins with cholesterol, and with anionic lipids such as phosphatidylinositol 4,5-bis-phosphate and cardiolipin. Peripheral membrane proteins are exemplified via interactions of PH domains with phosphoinositide-containing membranes. We summarise the current state of the field and provide an outlook on likely future directions of investigation.

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Section: Protein-lipid Interactions: Structures and Simulationsmentioning

confidence: 99%

The energetics of protein–lipid interactions as viewed by molecular simulations

Corey

Stansfeld

Sansom

2019

Biochemical Society Transactions

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“…TMEM16A and TMEM16B are Ca 2+ -activated Cl - channels (CaCCs), which participate in fluid secretion, smooth muscle contraction, gut motility, nociception, motor learning, anxiety and cancer (Hartzell, Putzier and Arreola, 2005; Caputo et al ., 2008; Yang et al ., 2008; Schroeder et al ., 2008; Berg, Yang and Jan, 2012; Cho et al ., 2012; Huang et al ., 2012; Pedemonte and Galietta, 2014; Oh and Jung, 2016; Whitlock and Hartzell, 2017; Zhang et al ., 2017; Crottès and Jan, 2019; Li et al ., 2019). Majority of the other TMEM16 members are likely not CaCCs (Suzuki et al ., 2010; Yang et al ., 2012; Huang et al ., 2013; Suzuki, Imanishi and Nagata, 2014; Whitlock et al ., 2018; Bushell, Ashley C.W. Pike, et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

“…The pore-gate domain of TMEM16 proteins consists of not only the permeation pathway for phospholipids and ions, but also two highly conserved Ca 2+ binding sites (Yu et al ., 2012; Brunner et al ., 2014; Tien et al ., 2014). Binding of intracellular Ca 2+ (Ca 2+ i ) triggers conformational changes, which lead to the opening of the activation gates and subsequent lipid and ion permeation (Dang et al ., 2017; Paulino et al ., 2017; Alvadia et al ., 2019; Bushell, Ashley C. W. Pike, et al ., 2019; Feng et al ., 2019; T. Le et al ., 2019). In addition to Ca 2+ i , membrane depolarization also facilitates the activation of TMEM16 CaCCs and TMEM16F ion channels (Yang et al ., 2008, 2012; Dang et al ., 2017; Paulino et al ., 2017).…”

Section: Introductionmentioning

confidence: 99%

Molecular underpinning of intracellular pH regulation on TMEM16F

Liang¹,

Yang

2020

Preprint

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39TMEM16F, a dual functional phospholipid scramblase and ion channel, is important in blood 40 coagulation, skeleton development, HIV infection and cell fusion. Despite the advances in 41 understanding its structure and activation mechanism, how TMEM16F is regulated by intracellular 42 factors remains largely elusive. Here we report that TMEM16F lipid scrambling and ion channel 43 activities are strongly influenced by intracellular pH (pHi). We find that low pHi attenuates 44 whereas high pHi potentiates TMEM16F activation. Our biophysical characterizations pinpoint 45 that the pHi regulatory effects on TMEM16F stem from protonation and deprotonation of the Ca 2+ 46 binding sites, which in turn reduces and enhances Ca 2+ binding affinity, respectively. We further 47 demonstrate that intracellular alkalization of 0.5 pHi can significantly promote TMEM16F 48 activities in a choriocarcinoma cell line. Our findings thus uncover a regulatory mechanism of 49 TMEM16F by pHi and shine light on understanding the pathophysiological roles of TMEM16F in 50 diseases with dysregulated pHi including cancer. 51 52

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“…Finally, it is intriguing that the membrane-embedded portion of Ist2 bears structural homology to the mammalian TMEM16 family of proteins, which function as Ca 2+ -activated lipid scramblases and/or ion channels in the PM or in the ER (Falzone et al, 2018;Bushell et al, 2019). Since PS is synthesized exclusively on the cytosolic side of the ER (Chauhan et al, 2016), lipid scrambling would be another way to regulate the size of the PS pool available for transport by a cytosolic LTP.…”

Section: Discussionmentioning

confidence: 99%

Osh6 requires Ist2 for localization to the ER-PM contacts and efficient phosphatidylserine transport

D’Ambrosio

Albanèse

Lipp

et al. 2020

Preprint

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Osh6 and Osh7 are lipid transfer proteins (LTPs) that transport phosphatidylserine (PS) from the endoplasmic reticulum (ER) to the plasma membrane (PM). High PS level at the PM is key for many cellular functions. Intriguingly, Osh6/7 localize to ER-PM contact sites, although they lack membrane-targeting motifs, in contrast to multidomain LTPs that both bridge membranes and convey lipids. We show that Osh6 localization to contact sites depends on its interaction with the cytosolic tail of the ER-PM tether Ist2, a homologue of TMEM16 proteins. We identify a motif in the Ist2 tail, conserved in yeasts, as the Osh6-binding region, and we map an Ist2-binding surface on Osh6. Mutations in the Ist2 tail phenocopy osh6D osh7D deletion: they decrease cellular PS levels, and block PS transport to the PM. Our study unveils an unexpected partnership between a TMEM16-like protein and a soluble LTP, which together mediate lipid transport at contact sites.

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The structural basis of lipid scrambling and inactivation in the endoplasmic reticulum scramblase TMEM16K

Cited by 135 publications

References 75 publications

The energetics of protein–lipid interactions as viewed by molecular simulations

The energetics of protein–lipid interactions as viewed by molecular simulations

Molecular underpinning of intracellular pH regulation on TMEM16F

Osh6 requires Ist2 for localization to the ER-PM contacts and efficient phosphatidylserine transport

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