Protonation‐Driven Membrane Insertion of a pH‐Low Insertion Peptide

Hanz, Samuel Z.; Shu, Nicolas S.; Qian, Jieni; Christman, Nathaniel; Kranz, Patrick; An, Ming; Grewer, Christof; Wang, Qiang

doi:10.1002/anie.201605203

Cited by 37 publications

(64 citation statements)

References 39 publications

(179 reference statements)

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“…molecular details of how protonations lead to pHLIP insertion were not known. A key breakthrough obtained with ssNMR established the sequence of protonations that led to pHLIP membrane insertion, which, in turn, defined the protonation-state intermediates (30). The specific side-chain pK a values of D residues were determined to be 6.5 (D31), 6.3 (D33), 6.1 (D25), and 5.8 (D14) (30).…”

Section: Significancementioning

confidence: 99%

“…A key breakthrough obtained with ssNMR established the sequence of protonations that led to pHLIP membrane insertion, which, in turn, defined the protonation-state intermediates (30). The specific side-chain pK a values of D residues were determined to be 6.5 (D31), 6.3 (D33), 6.1 (D25), and 5.8 (D14) (30). Since the pK a values are well separated (i.e., the titration curves of D31, D25, and D14 did not overlap), the protonations of pHLIP are largely sequential along the insertion pH gradient (30).…”

Section: Significancementioning

confidence: 99%

“…The specific side-chain pK a values of D residues were determined to be 6.5 (D31), 6.3 (D33), 6.1 (D25), and 5.8 (D14) (30). Since the pK a values are well separated (i.e., the titration curves of D31, D25, and D14 did not overlap), the protonations of pHLIP are largely sequential along the insertion pH gradient (30). Thus, we postulate that thermodynamic, pH-specific intermediate states distinct from the initial state II and the final state III exist at intervening pH values, and, furthermore, they are defined by specific overall protonation states.…”

Section: Significancementioning

confidence: 99%

“…At pH 5.3, pHLIP is known to form an interrupted TM α-helix with N terminus on the outside of the membrane (state III) (11,15,30). We previously determined that the peptide backbone conformation at pH 5.3 contained two segments of helices separated by a short break at residues T19−P20 (30). Furthermore, residues A10 and A13 were located 5.7 Å and 7.8 Å, respectively, away from 31 P, while A27 was >10 Å away (23).…”

Section: Semiquantitative Redor Analysis On States II and Iii Of Phlipmentioning

confidence: 99%

“…The general principle of how acidity induces pHLIP membrane insertion was thought to be the following: At high pH, side chains of D residues in the TM region are negatively charged; when pH is lowered, the protonations of these D residues increase peptide hydrophobicity, favoring pHLIP relocation from the polar membrane surface to the hydrophobic interior (as well as folding of the TM helix) (1,21,(27)(28)(29). However, before our solid-state NMR (ssNMR) spectroscopy studies (23,30), the…”

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confidence: 99%

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pH-dependent thermodynamic intermediates of pHLIP membrane insertion determined by solid-state NMR spectroscopy

Otieno

Hanz

Chakravorty

et al. 2018

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

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The applications of the pH low insertion peptide (pHLIP) in cancer diagnosis and cross-membrane cargo delivery have drawn increasing attention in the past decade. With its origin as the transmembrane (TM) helix C of bacteriorhodopsin, pHLIP is also an important model for understanding how pH can affect the folding and topogenesis of a TM α-helix. Protonations of multiple D/E residues transform pHLIP from an unstructured coil at membrane surface (known as state II, at pH ≥ 7) to a TM α-helix (state III, pH ≤ 5.3). While these initial and end states of pHLIP insertion have been firmly established, what happens at the intervening pH values is less clear. However, the intervening pH range is most relevant to pHLIP−cell interactions in the acidic extracellular tumor environment (and in the endosomes within cells). Here, using advanced solid-state NMR spectroscopy with palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine unilamellar vesicles as the model membrane, we systematically examined the state of pHLIP−membrane interactions (in terms of the membrane locations of D/E residues, as well as lipid dynamics) at the intervening pH values of 6.4, 6.1, and 5.8, along with the known states at pH 7.4 and 5.3. Thermodynamic intermediate states distinct from the initial and end states were discovered to exist at each of the intervening pH examined. They support a multistage model of pHLIP insertion in which the D/E titrations occur in a defined sequence at distinct intermediate pH values. This multistage model has important ramifications in pHLIP applications.

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Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Semiquantitative Redor Analysis On States II and Iii Of Phlipmentioning

confidence: 99%

mentioning

confidence: 99%

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pH-dependent thermodynamic intermediates of pHLIP membrane insertion determined by solid-state NMR spectroscopy

Otieno

Hanz

Chakravorty

et al. 2018

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

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Glycopeptide‐Based Multifunctional Hydrogels Promote Diabetic Wound Healing through pH Regulation of Microenvironment

Xia

Dong

Tang

et al. 2023

Adv Funct Materials

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Excessive inflammation, bacterial infection, and blocked angiogenesis make diabetic wound healing challenging. Multifunctional wound dressings have several advantages in diabetic wound healing. In addition, the pH regulation of the microenvironment is shown to be a key factor that promotes skin regeneration through cellular immune regulation. However, few reports have focused on the development of functional dressings with the ability to regulate the pH microenvironment and promote diabetic wound healing. This study presents a novel approach for regulating the pH microenvironment of diabetic wound sites using a glycopeptide-based hydrogel consisting of modified hyaluronic acid and poly(6-aminocaproic acid). This hydrogel forms a network through Schiff base interactions and metal complexation, which suppresses inflammation and accelerates angiogenesis during wound healing. Hydrogels not only have adequate mechanical properties and self-healing ability but can also support tissue adhesion. They can also promote the secretion of inducible cAMP early repressor, which promotes the polarization of macrophages toward the M2 type. The in vivo results confirm that hydrogel promotes diabetic wound repair and skin regeneration by exerting rapid antiinflammatory effects and promoting angiogenesis. Therefore, this hydrogel system represents an effective strategy for treating diabetic wounds.

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Construction of Liposomes Mimicking Cell Membrane Structure through Frame‐Guided Assembly

Wang

Piao

et al. 2020

Angewandte Chemie

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The shape of eukaryotic cells is determined by the cytoskeleton associated with membrane proteins; however, the detailed mechanism of how the integral morphologies with structural stability is generated and maintained is still not fully understood. Here, based on the Frame‐Guided Assembly (FGA) strategy, we successfully prepared hetero‐liposomes with structural composition similar to that of eukaryotic cells by screening a series of transmembrane peptides as the leading hydrophobic groups (LHGs). It was demonstrated that the conformation and transmembrane mode of the LHGs played dominant roles during the FGA process. The FGA liposomes were formed with excellent stability, which may further provide evidence for the cytoskeleton–membrane protein–lipid bilayer model. Taking advantage of the biocompatibility and stability, the FGA liposomes were also applied to prepare novel drug delivery vehicles, which is promising in diagnostic imaging and cancer therapy applications.

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Protonation‐Driven Membrane Insertion of a pH‐Low Insertion Peptide

Cited by 37 publications

References 39 publications

pH-dependent thermodynamic intermediates of pHLIP membrane insertion determined by solid-state NMR spectroscopy

pH-dependent thermodynamic intermediates of pHLIP membrane insertion determined by solid-state NMR spectroscopy

Glycopeptide‐Based Multifunctional Hydrogels Promote Diabetic Wound Healing through pH Regulation of Microenvironment

Construction of Liposomes Mimicking Cell Membrane Structure through Frame‐Guided Assembly

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