Human neuroserpin (hNS) is a serine protease inhibitor that belongs to the serpin superfamily and is expressed in nervous tissues. The serpin fold is generally characterized by a long exposed loop, termed the reactive center loop, that acts as bait for the target protease. Intramolecular insertion of the reactive center loop into the main serpin beta-sheet leads to the serpin latent form. As with other known serpins, hNS pathological mutants have been shown to accumulate as polymers composed of quasi-native protein molecules. Although hNS polymerization has been intensely studied, a general agreement about serpin polymer organization is still lacking. Here we report a biophysical characterization of native hNS that is shown to undergo two distinct conformational transitions, at 55 degrees C and 85 degrees C, both leading to distinct latent and polymeric species. The latent and polymer hNS forms obtained at 45 degrees C and 85 degrees C differ in their chemical and thermal stabilities; furthermore, the hNS polymers also differ in size and morphology. Finally, the 85 degrees C polymer shows a higher content of intermolecular beta-sheet interactions than the 45 degrees C polymer. Together, these results suggest a more complex conformational scenario than was previously envisioned, and, in a general context, may help reconcile the current contrasting views on serpin polymerization.
Two latent and two hyperstable polymeric forms of human neuroserpin / S. Ricagno, M. Pezzullo, A. Barbiroli, M. Manno, M. Levantino, M.G. Santangelo, F. Bonomi, M. Bolognesi. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - 99:10(2010), pp. 3402-3411. [10.1016/j.bpj.2010.09.021]
Two latent and two hyperstable polymeric forms of human neuroserpin
S. RicagnoPrimo
;M. PezzulloSecondo
;A. Barbiroli;F. BonomiPenultimo
;M. BolognesiUltimo
2010
Abstract
Human neuroserpin (hNS) is a serine protease inhibitor that belongs to the serpin superfamily and is expressed in nervous tissues. The serpin fold is generally characterized by a long exposed loop, termed the reactive center loop, that acts as bait for the target protease. Intramolecular insertion of the reactive center loop into the main serpin beta-sheet leads to the serpin latent form. As with other known serpins, hNS pathological mutants have been shown to accumulate as polymers composed of quasi-native protein molecules. Although hNS polymerization has been intensely studied, a general agreement about serpin polymer organization is still lacking. Here we report a biophysical characterization of native hNS that is shown to undergo two distinct conformational transitions, at 55 degrees C and 85 degrees C, both leading to distinct latent and polymeric species. The latent and polymer hNS forms obtained at 45 degrees C and 85 degrees C differ in their chemical and thermal stabilities; furthermore, the hNS polymers also differ in size and morphology. Finally, the 85 degrees C polymer shows a higher content of intermolecular beta-sheet interactions than the 45 degrees C polymer. Together, these results suggest a more complex conformational scenario than was previously envisioned, and, in a general context, may help reconcile the current contrasting views on serpin polymerization.Pubblicazioni consigliate
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