Biophysical and structural characterization of the small heat shock protein HspA from Thermosynechococcus vulcanus in 2 M urea

Ghosh, Sudeshna; Salama, Faris; Dines, Monica; Lahav, A.; Adir, Noam

doi:10.1016/j.bbapap.2018.12.011

Cited by 3 publications

(1 citation statement)

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“…We have demonstrated that 2 M urea is sufficient to extract much of the folded and functional BBP from the E. coli cell debris, preserving the absorbance spectrum with the high Vis/UV absorbance ratio of ~4 characteristic of the same protein extracted in the absence of urea. While urea is often used as a denaturing agent, this result is not unexpected since previous works demonstrated that tested proteins preserve native-like conformation in 2 M urea [51][52][53] . The recombinant dimeric BBP is saturated by carotenoid and is free from the apoprotein, probably because the latter is rather unstable.…”

Section: Discussionmentioning

confidence: 69%

Insights into the molecular mechanism of yellow cuticle coloration by a chitin-binding carotenoprotein in gregarious locusts

Egorkin,

Dominnik,

Maksimov

et al. 2024

Commun Biol

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Carotenoids are hydrophobic pigments binding to diverse carotenoproteins, many of which remain unexplored. Focusing on yellow gregarious locusts accumulating cuticular carotenoids, here we use engineered Escherichia coli cells to reconstitute a functional water-soluble β-carotene-binding protein, BBP. HPLC and Raman spectroscopy confirmed that recombinant BBP avidly binds β-carotene, inducing the unusual vibronic structure of its absorbance spectrum, just like native BBP extracted from the locust cuticles. Bound to recombinant BBP, β-carotene exhibits pronounced circular dichroism and allows BBP to withstand heating (T0.5 = 68 °C), detergents and pH variations. Using bacteria producing distinct xanthophylls we demonstrate that, while β-carotene is the preferred carotenoid, BBP can also extract from membranes ketocarotenoids and, very poorly, hydroxycarotenoids. We show that BBP-carotenoid complex reversibly binds to chitin, but not to chitosan, implying the role for chitin acetyl groups in cuticular BBP deposition. Reconstructing such locust coloration mechanism in vitro paves the way for structural studies and BBP applications.

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Section: Discussionmentioning

confidence: 69%