Probing the Conformational and Energy Landscapes of KRAS Membrane Orientation

Prakash, Priyanka; Gorfe, Alemayehu A.

doi:10.1021/acs.jpcb.9b05796

Cited by 47 publications

(43 citation statements)

References 51 publications

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“…In some of these orientations, the G-domain is unable to interact with effectors because of the occlusion of the switch loops by the membrane. The simulations have also shown that the relative disposition of the HVR and the G-domain underpin membrane reorientation [58][59][60].…”

Section: Activation State Dependent Orientations Of Ras On the Membranementioning

confidence: 86%

“…Following the original report on H-Ras [16], extensive MD simulations in recent years have shown that the G-domain of G12D [58], G12V [59], Q61H [60] and wild type K-Ras [61] directly interacts with membrane lipids via multiple distinct orientations. In some of these orientations, the G-domain is unable to interact with effectors because of the occlusion of the switch loops by the membrane.…”

Section: Activation State Dependent Orientations Of Ras On the Membranementioning

confidence: 99%

See 1 more Smart Citation

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Abankwa¹,

Gorfe²

2020

Preprint

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Ras is the most frequently mutated oncogene and recent drug development efforts have spurred significant new research interest. Here we will review progress toward understanding how Ras functions in nanoscale, proteo-lipid signaling complexes on the plasma membrane, called nanocluster. We will discuss how G-domain reorientation is plausibly linked to Ras-nanoclustering and -dimerization. We will then look at how these mechanistic features could cooperate in the engagement and activation of RAF by Ras. Moreover, we will show how this structural information can be integrated with microscopy data that provide nanoscale resolution in cell biological experiments. Synthesizing the available data, we propose to distinguish between two types of Ras nanoclusters, an active, immobile RAF-dependent type and an inactive/ neutral membrane anchor-dependent. We conclude that it is possible that Ras reorientation enables dynamic Ras dimerization, while the whole Ras/ RAF complex transits into an active state. These transient di/oligomer interfaces of Ras may be amenable to pharmacological intervention. We close by highlighting a number of open questions including, whether all effectors form active nanoclusters and whether there is an isoform specific composition of Ras nanocluster.

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Section: Activation State Dependent Orientations Of Ras On the Membranementioning

confidence: 86%

Section: Activation State Dependent Orientations Of Ras On the Membranementioning

confidence: 99%

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Abankwa¹,

Gorfe²

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Activation State Dependent Orientations Of Ras On the Membranementioning

confidence: 97%

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Abankwa

Gorfe

2020

Biomolecules

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Ras is the most frequently mutated oncogene and recent drug development efforts have spurred significant new research interest. Here we review progress toward understanding how Ras functions in nanoscale, proteo-lipid signaling complexes on the plasma membrane, called nanoclusters. We discuss how G-domain reorientation is plausibly linked to Ras-nanoclustering and -dimerization. We then look at how these mechanistic features could cooperate in the engagement and activation of RAF by Ras. Moreover, we show how this structural information can be integrated with microscopy data that provide nanoscale resolution in cell biological experiments. Synthesizing the available data, we propose to distinguish between two types of Ras nanoclusters, an active, immobile RAF-dependent type and an inactive/neutral membrane anchor-dependent. We conclude that it is possible that Ras reorientation enables dynamic Ras dimerization while the whole Ras/RAF complex transits into an active state. These transient di/oligomer interfaces of Ras may be amenable to pharmacological intervention. We close by highlighting a number of open questions including whether all effectors form active nanoclusters and whether there is an isoform specific composition of Ras nanocluster.

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“…These results suggest that the two (Asn-Lys) or six (Asn-Lys-Ile-Glu-Ser-Gly) N-terminal residues in the Rab4a HRV linker domain contribute to limiting the intrinsic tethering potency of the G-domain through their interactions with the polar lipid headgroups. Considering that recent computational studies by molecular dynamics simulations of membrane-bound K-Ras, belonging to the Ras superfamily, reported the multiple orientation states of the K-Ras G-domain on the membrane surface that are affected by the C-terminal HVR linker and anionic membrane lipids (Prakash et al, 2016;Prakash and Gorfe, 2019;Neale and Garcia, 2020;Ngo et al, 2020), it is conceivable that the hydrophilic interactions between the N-terminal residues of the Rab4a HVR linker and anionic lipids may guide the G-domain into the specific "tetheringincompetent" membrane orientation.…”

Section: Critical Residues In the Hvr Linker Domain Of Rab4a For Regumentioning

confidence: 99%

Membrane tethering potency of Rab-family small GTPases is defined by the C-terminal hypervariable regions

Ueda

Tamura

Mima

2020

Preprint

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AbstractMembrane tethering is a crucial step to determine the spatiotemporal specificity of secretory and endocytic trafficking pathways in all eukaryotic endomembrane systems. Recent biochemical studies by a chemically-defined reconstitution approach reveal that, in addition to the structurally-diverse classic tethering factors such as coiled-coil tethering proteins and multisubunit tethering complexes, Rab-family small GTPases also retain the inherent membrane tethering functions to directly and physically bridge two distinct lipid bilayers by themselves. Although Rab-mediated membrane tethering reactions are fairly efficient and specific in the physiological context, its mechanistic basis is yet to be understood. Here, to explore whether and how the intrinsic tethering potency of Rab GTPases is controlled by their C-terminal hypervariable region (HVR) domains that link the conserved small GTPase domains (G-domains) to membrane anchors at the C-terminus, we quantitatively compared tethering activities of two representative Rab isoforms in humans (Rab5a, Rab4a) and their HVR-deleted mutant forms. Strikingly, deletion of the HVR linker domains enabled both Rab5a and Rab4a isoforms to drastically enhance their intrinsic tethering potency, exhibiting 5- to 50-fold higher initial velocities of tethering for the HVR-deleted mutants than those for the full-length, wild-type Rabs. Furthermore, we revealed that the tethering activity of full-length Rab5a was significantly reduced by the omission of anionic lipids and cholesterol from membrane lipids and, however, membrane tethering driven by HVR-deleted Rab5a mutant was completely insensitive to the headgroup composition of lipids. In conclusion, our current findings establish that the non-conserved, flexible C-terminal HVR linker domains define membrane tethering potency of Rab-family small GTPases through controlling the close attachment of the globular G-domains to membrane surfaces, which confers the active tethering-competent state of the G-domains on lipid bilayers.

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Probing the Conformational and Energy Landscapes of KRAS Membrane Orientation

Cited by 47 publications

References 51 publications

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Mechanisms of Ras Membrane Organization and Signaling: Ras Rocks Again

Membrane tethering potency of Rab-family small GTPases is defined by the C-terminal hypervariable regions

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