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Palmitoylation as a key factor to modulate SP-C–lipid interactions in lung surfactant membrane multilayers

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Roldán López, Nuria and Goormaghtigh, Erik and Pérez Gil, Jesús and García Álvarez, Begoña (2015) Palmitoylation as a key factor to modulate SP-C–lipid interactions in lung surfactant membrane multilayers. Biochimica et Biophysica Acta, 1848 (1A). pp. 184-191. ISSN 0006-3002

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Official URL: http://www.sciencedirect.com/science/journal/00052736/1848/1/supp/PA



Abstract

Surfactant protein C (SP-C) has been regarded as the most specific protein linked to development of mammalian lungs, and great efforts have been done to understand its structure–function relationships. Previous evidence has outlined the importance of SP-C palmitoylation to sustain the proper dynamics of lung surfactant, but the mechanism by which this posttranslational modification aids SP-C to stabilize the interfacial surfactant film along the compression–expansion breathing cycles, is still unrevealed. In this work we have compared the structure, orientation and lipid–protein interactions of a native palmitoylated SP-C with those of a non-palmitoylated recombinant SP-C (rSP-C) form in air-exposed multilayer membrane environments, by means of ATR-FTIR spectroscopy. Palmitoylation does not affect the secondary structure of the protein, which exhibits a full α-helical conformation in partly dehydrated phospholipid multilayer films. However, differences between the Amide I band of the IR spectrum of palmitoylated and non-palmitoylated proteins suggest subtle differences affecting the environment of their helical component. These differences are accompanied by differential effects on the IR bands from phospholipid phosphates, indicating that palmitoylation modulates lipid–protein interactions at the headgroup region of phospholipid layers. On the other hand, the relative dichroic absorption of polarized IR has allowed calculating that the palmitoylated protein adopts a more tilted transmembrane orientation than the non-palmitoylated SP-C, likely contributing to more compact, dehydrated and possibly stable multilayer lipid–protein films. As a whole, the behavior of multilayer films containing palmitoylated SP-C may reflect favorable structural properties for surfactant reservoirs at the air–liquid respiratory interface.


Item Type:Article
Uncontrolled Keywords:SP-C; Palmitoylation; Lung surfactant; ATR-FTIR; Protein–lipid interaction
Subjects:Medical sciences > Biology
Medical sciences > Biology > Molecular biology
ID Code:43415
Deposited On:16 Jun 2017 17:20
Last Modified:27 Feb 2018 09:02

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