RT Journal Article
T1 Exploring protein–protein interactions and oligomerization state of pulmonary surfactant protein C (SP‐C) through FRET and fluorescence self‐quenching
A1 Morán Lalangui, Juranny Michelle
A1 Coutinho, Ana
A1 Prieto, Manuel
A1 Fedorov, Alexander
A1 Pérez Gil, Jesús
A1 Loura, Luis M. S.
A1 García Álvarez, María Begoña
AB Pulmonary surfactant (PS) is a lipid–protein complex that forms films reducing surface tension at the alveolar air–liquid interface. Surfactant protein C (SP-C) plays a key role in rearranging the lipids at the PS surface layers during breathing. The N-terminal segment of SP-C, a lipopeptide of 35 amino acids, contains two palmitoylated cysteines, which affect the stability and structure of the molecule. The C-terminal region comprises a transmembrane α-helix that contains a ALLMG motif, supposedly analogous to a well-studied dimerization motif in glycophorin A. Previous studies have demonstrated the potential interaction between SP-C molecules using approaches such as Bimolecular Complementation assays or computational simulations. In this work, the oligomerization state of SP-C in membrane systems has been studied using fluorescence spectroscopy techniques. We have performed self-quenching and FRET assays to analyze dimerization of native palmitoylated SP-C and a non-palmitoylated recombinant version of SP-C (rSP-C) using fluorescently labeled versions of either protein reconstituted in different lipid systems mimicking pulmonary surfactant environments. Our results reveal that doubly palmitoylated native SP-C remains primarily monomeric. In contrast, non-palmitoylated recombinant SP-C exhibits dimerization, potentiated at high concentrations, especially in membranes with lipid phase separation. Therefore, palmitoylation could play a crucial role in stabilizing the monomeric α-helical conformation of SP-C. Depalmitoylation, high protein densities as a consequence of membrane compartmentalization, and other factors may all lead to the formation of protein dimers and higher-order oligomers, which could have functional implications under certain pathological conditions and contribute to membrane transformations associated with surfactant metabolism and alveolar homeostasis.
PB John Wiley & Sons
SN 0961-8368
YR 2023
FD 2023-11-20
LK https://hdl.handle.net/20.500.14352/120659
UL https://hdl.handle.net/20.500.14352/120659
LA eng
NO Morán-Lalangui, M., Coutinho, A., Prieto, M., Fedorov, A., Pérez-Gil, J., Loura, L. M. S., & García-Álvarez, B. (2024). Exploring protein–protein interactions and oligomerization state of pulmonary surfactant protein C (SP-C) through FRET and fluorescence self-quenching. Protein Science, 33(1). https://doi.org/10.1002/PRO.4835
NO Begoña García-Álvarez and Jesús Pérez-Gil thanks Spanish Ministry of Science and Innovation Grant (PID2021-124932OB-100) and Community of Madrid Grant (Nanobiocargo P2018/NMT-4389) for funding this study. Mishelle Morán-Lalangui is a recipient of a FPI fellowship from the Spanish Ministry of Science and Innovation. Luís M. S. Loura acknowledges funding by the European Regional Development Fund, through COMPETE2020-Operational Program for Competitiveness and Internationalization, and Portuguese funds via FCT-Fundação para a Ciência e a Tecnologia, under projects UIDB/00313/2020 and UIDP/00313/2020 (Portugal). Ana Coutinho and Manuel Prieto acknowledge funding from FCT-Fundação para a Ciência e a Tecnologia, under projects UIDB/04565/2020, UIDP/04565/2020 and LA/P/0140/2020 (Portugal). This work has been supported by a working visit bursary from EBSA.
NO Ministerio de Ciencia e Innovación (España)
NO Comunidad de Madrid
NO European Commission
NO Fundação para a Ciência e a Tecnologia (Portugal)
NO European Biophysical Societies Association
DS Docta Complutense
RD 24 dic 2025