Binding Affinity and Function of the Extremely Disordered Protein Complex Containing Human Linker Histone H1.0 and Its Chaperone ProTα

Feng, Hanqiao; Zhou, Bing-Rui; Bai, Yawen

doi:10.1021/acs.biochem.8b01075

Cited by 30 publications

(32 citation statements)

References 10 publications

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“…1). The perturbation of the affinity by the fluorophores is thus small, at most on the order of thermal energy (k B T), in contrast to recent speculative concerns 16 . For comparison, a similar effect on binding free energy results from a change in solution ionic strength by a mere 10-20 mM.…”

Section: Resultsmentioning

confidence: 83%

Polyelectrolyte interactions enable rapid association and dissociation in high-affinity disordered protein complexes

et al. 2020

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Highly charged intrinsically disordered proteins can form complexes with very high affinity in which both binding partners fully retain their disorder and dynamics, exemplified by the positively charged linker histone H1.0 and its chaperone, the negatively charged prothymosin α. Their interaction exhibits another surprising feature: The association/dissociation kinetics switch from slow two-state-like exchange at low protein concentrations to fast exchange at higher, physiologically relevant concentrations. Here we show that this change in mechanism can be explained by the formation of transient ternary complexes favored at high protein concentrations that accelerate the exchange between bound and unbound populations by orders of magnitude. Molecular simulations show how the extreme disorder in such polyelectrolyte complexes facilitates (i) diffusion-limited binding, (ii) transient ternary complex formation, and (iii) fast exchange of monomers by competitive substitution, which together enable rapid kinetics. Biological polyelectrolytes thus have the potential to keep regulatory networks highly responsive even for interactions with extremely high affinities.

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Section: Resultsmentioning

confidence: 83%

Polyelectrolyte interactions enable rapid association and dissociation in high-affinity disordered protein complexes

et al. 2020

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“…9B). Notably, multiple theoretical and experimental studies have shown that the sequence-specific electrostatically driven interactions between disordered proteins can lead to LLPS and high affinity protein complex formation under physiological conditions, with the tendency to phase separate (or undergo 'complex coacervation') increasing as the 'blockiness' of the charge distribution increases [67][68][69][70][71][72] .…”

Section: Discussionmentioning

confidence: 99%

“…Although Cavin1 and CAV1 are associated together in caveolae, it remains unclear whether they interact with each other via direct protein-protein interactions. CAV1 has a unique structural domain architecture shared with other caveolins, consisting of an N-terminal disordered region (DR) (1-60), followed by an oligomerization domain (OD) (61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78)(79)(80), scaffolding domain (CSD) (81-100), intramembrane domain (IMD) (101-133) and a C-terminal membrane associated a-helical domain (134-179) ( Fig. 3A; Fig.…”

Section: Cavin1 Promotes Co-phase Separation With N-terminal Regions mentioning

confidence: 99%

Cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation

Tillu

Rae

et al. 2019

Preprint

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Caveolae are spherical-structured nanodomains of the plasma membrane, generated by cooperative assembly of caveolin and cavin proteins. Cavins are cytosolic peripheral membrane proteins with negatively charged intrinsically disordered regions (DR1-3) that flank positively charged a-helical regions (HR1 and HR2). Here we show that the three DR domains of Cavin1 are essential for caveola formation and dynamic trafficking of caveolae. Electrostatic interactions between DR and HR regions promote liquid-liquid phase separation behaviour of Cavin1, assembly of Cavin1 polymers in solution, generation of membrane curvature in a reconstituted system, and Cavin1 recruitment to caveolae in cells. Removal of the first disordered region causes irreversible gel formation in vitro and results in aberrant caveola trafficking through the endosomal system. We propose a model for caveola assembly whereby fuzzy electrostatic interactions between Cavin1 proteins, combined with CAV1 and membrane lipid interactions, are required to generate membrane curvature and a metastable caveola coat.

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“…Note Added in Proof. During review, a study was published that implicated fluorophores in the strengthening of the binding affinity between two IDPs (83).…”

Section: Methodsmentioning

confidence: 99%

Commonly used FRET fluorophores promote collapse of an otherwise disordered protein

Riback

Bowman

Zmyslowski

et al. 2019

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

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The dimensions that unfolded proteins, including intrinsically disordered proteins (IDPs), adopt in the absence of denaturant remain controversial. We developed an analysis procedure for small-angle X-ray scattering (SAXS) profiles and used it to demonstrate that even relatively hydrophobic IDPs remain nearly as expanded in water as they are in high denaturant concentrations. In contrast, as demonstrated here, most fluorescence resonance energy transfer (FRET) measurements have indicated that relatively hydrophobic IDPs contract significantly in the absence of denaturant. We use two independent approaches to further explore this controversy. First, using SAXS we show that fluorophores employed in FRET can contribute to the observed discrepancy. Specifically, we find that addition of Alexa-488 to a normally expanded IDP causes contraction by an additional 15%, a value in reasonable accord with the contraction reported in FRET-based studies. Second, using our simulations and analysis procedure to accurately extract both the radius of gyration (Rg) and end-to-end distance (Ree) from SAXS profiles, we tested the recent suggestion that FRET and SAXS results can be reconciled if the Rg and Ree are “uncoupled” (i.e., no longer simply proportional), in contrast to the case for random walk homopolymers. We find, however, that even for unfolded proteins, these two measures of unfolded state dimensions remain proportional. Together, these results suggest that improved analysis procedures and a correction for significant, fluorophore-driven interactions are sufficient to reconcile prior SAXS and FRET studies, thus providing a unified picture of the nature of unfolded polypeptide chains in the absence of denaturant.

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Binding Affinity and Function of the Extremely Disordered Protein Complex Containing Human Linker Histone H1.0 and Its Chaperone ProTα

Cited by 30 publications

References 10 publications

Polyelectrolyte interactions enable rapid association and dissociation in high-affinity disordered protein complexes

Polyelectrolyte interactions enable rapid association and dissociation in high-affinity disordered protein complexes

Cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation

Commonly used FRET fluorophores promote collapse of an otherwise disordered protein

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