Membrane proteins bind lipids selectively to modulate their structure and function

Laganowsky, Arthur; Reading, Eamonn; Allison, Timothy M.; Ulmschneider, Martin B.; Degiacomi, Matteo T.; Baldwin, Andrew J.; Robinson, Carol V.

doi:10.1038/nature13419

Cited by 717 publications

(858 citation statements)

References 69 publications

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“…Tb-MscL is bigger than E. coli MscL. Indeed, in the study of Laganowsky et al (33), the molecular mass and collision crosssection (CCS) of M. tuberculosis MscL was measured as 85,578 Da and 5,438.5 Å 2 , whereas we measured the same parameters for WT E. coli MscL as 78,342 Da and 4,861 Å 2 (Table S2).…”

Section: Significancementioning

confidence: 88%

“…Our approach, using detergent micelles that are unstable in the gas phase, allowed for the detection of native pentamer of E. coli MscL by IM-MS. Recently, a study on determining the specificity of membrane proteins toward lipids reported that a homologous MscL channel from Mycobacterium tuberculosis (Tb-MscL) also keeps its folded conformation in the gas phase of IM-MS (33). MscL from these two organisms differ in their molecular weight, tension sensitivity, and lipid interactions.…”

Section: Significancementioning

confidence: 99%

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Global structural changes of an ion channel during its gating are followed by ion mobility mass spectrometry

Konijnenberg

Yilmaz²,

Ingólfsson

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Mechanosensitive ion channels are sensors probing membrane tension in all species; despite their importance and vital role in many cell functions, their gating mechanism remains to be elucidated. Here, we determined the conditions for releasing intact mechanosensitive channel of large conductance (MscL) proteins from their detergents in the gas phase using native ion mobilitymass spectrometry (IM-MS). By using IM-MS, we could detect the native mass of MscL from Escherichia coli, determine various global structural changes during its gating by measuring the rotationally averaged collision cross-sections, and show that it can function in the absence of a lipid bilayer. We could detect global conformational changes during MscL gating as small as 3%. Our findings will allow studying native structure of many other membrane proteins.ion mobility mass spectrometry | MscL | membrane proteins | structure function | ion channel gating O ne of the best candidates to explore the gating of mechanosensitive channels is the mechanosensitive channel of large conductance (MscL) from Escherichia coli. The crystal structure of MscL in its closed/nearly closed state from Mycobacterium tuberculosis revealed this channel as a homopentamer (1). Each subunit has a cytoplasmic N-and C-terminal domain as well as two α-helical transmembrane (TM) domains, TM1 and TM2, which are connected by a periplasmic loop. The five TM1 helices form the pore and the more peripheral TM2 helices interact with the lipid bilayer.MscL detects changes in membrane tension invoked by a hypoosmotic shock and couples the tension sensing directly to large conformational changes (1, 2). On the basis of a large body of structural and theoretical data, numerous gating models of MscL have been proposed (3-9). These models agree upon (i) the hydrophobic pore constriction of the channel and (ii) the channel opens by an iris-like rotation-i.e., a tilting and outward movement of transmembrane helices that make the channel wider and shorter (5). This mechanism is supported by patchclamp (10), disulfide cross-linking (11), FRET spectroscopy (12), and site-directed spin labeling EPR experiments (6, 7), as well as computational studies (13-15). So far, direct experimental results have only been observed for short-range local structural changes, and no measure of the overall global structural changes during channel gating have been reported. Because there is no crystal structure available for the open MscL channel, elucidating overall global structural changes from the onset of channel activation is of utmost importance for our understanding of the gating mechanism of mechanosensitive channels. Here, we provide direct experimental evidence for the key areal changes occurring during channel gating by combining our ability to activate MscL in a controlled manner to different subopen states (16) with a native ion mobility-mass spectrometry (IM-MS) approach. Results and DiscussionDetergents that are Unstable in the Gas Phase Allow Detection of MscL in Its Native Form. Native mass ...

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Section: Significancementioning

confidence: 88%

Section: Significancementioning

confidence: 99%

Global structural changes of an ion channel during its gating are followed by ion mobility mass spectrometry

Konijnenberg

Yilmaz²,

Ingólfsson

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Native mass spectrometry of MscL suggested the in vitro oligomerisation state (pentamer vs tetramer) is influenced by temperature, detergent and amino acid variability as well as by the precise construct used [18]. Protein stability has been shown to be influenced by the presence of particular lipids [19]. The variety of oligomeric states and their sensitivity to lipidation may explain the challenges in obtaing a structure of a fully open form.…”

Section: Bacterial Mechanosensors Mscs and Mscl: Open And Shut Storiesmentioning

confidence: 99%

Spectator no more, the role of the membrane in regulating ion channel function

Pliotas

Naismith

2017

Current Opinion in Structural Biology

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A pressure gradient across a curved lipid bilayer leads to a lateral force within the bilayer. Following ground breaking work on eukaryotic ion channels, it is now known that many proteins sense this change in the lateral tension and alter their functions in response. It has been proposed that responding to pressure differentials may be one of the oldest signaling mechanisms in biology. The most well characterized mechanosensing ion channels are the bacterial ones which open when the pressure differential hits a threshold. Recent studies on one of these channels, MscS, have developed a simple molecular model for how they sense and adapt to pressure.Biochemical and structural studies on mechanosensitive channels from eukaryotes have disclosed pressure sensing mechanisms. In this review, we highlight these findings and discuss the potential for a general model for pressure sensing.3

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“…Membrane lipids are known to greatly affect the structure and function of a number of membrane proteins, especially those interacting with hydrophobic or amphipathic substrates. Even in the cases of those membrane proteins, e.g., ion channels or hormone receptors, when the ligands are hydrophilic species, protein conformational changes are required to transmit the messages or ions through the membrane environment, and the energetics and speed of this information or material transfer may be greatly affected by lipid interactions (Laganowsky et al, 2014;Phillips, Ursell, Wiggins, & Sens, 2009). Basic categories of these physical and/or chemical interactions are summarized in (Fig.…”

Section: P0080mentioning

confidence: 99%