Biophysical properties of a synthetic transit peptide from wheat chloroplast ribulose 1,5-bisphosphate carboxylase

• Published in: Journal of peptide science Vol. 13; no. 4; pp. 245 - 252
• Main Authors: Ambroggio, Ernesto E., Austen, Brian, Fidelio, Gerardo D.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.04.2007
• Subjects: Biophysical Phenomena; Biophysics; chloroplast lipids; chloroplast transit peptide; Chloroplasts; FT-IR; langmuir monolayer; Lipids - chemistry; peptide lateral surface stability; peptide-lipid interaction; Peptides - chemical synthesis; Peptides - chemistry; Protein Conformation; Ribulose-Bisphosphate Carboxylase - chemistry; Sodium Dodecyl Sulfate - chemistry; Spectroscopy, Fourier Transform Infrared; Triticum - enzymology; Triticum aestivum
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.838

The surface properties of pure RuBisCo transit peptide (RTP) and its interaction with zwitterionic, anionic phospholipids and chloroplast lipids were studied by using the Langmuir monolayer technique. Pure RTP is able to form insoluble films and the observed surface parameters are compatible with an α‐helix perpendicular to the interface. The α‐helix structure tendency was also observed by using transmission FT‐IR spectroscopy in bulk system of a membrane mimicking environment (SDS). On the other hand, RTP adopts an unordered structure in either aqueous free interface or in the presence of vesicles composed of a zwitterionic phospholipid (POPC). Monolayer studies show that in peptide/lipid mixed monolayers, RTP shows no interaction with zwitterionic phospholipids, regardless of their physical state. Also, with the anionic POPG at high peptide ratios RTP retains its individual surface properties and behaves as an immiscible component of the peptide/lipid mixed interface. This behaviour was also observed when the mixed films were composed by RTP and the typical chloroplast lipids MGDG or DGDG (mono‐ and di‐galactosyldiacylglycerol). Conversely, RTP establishes a particular interaction with phosphatidylglycerol and cardiolipin at low peptide to lipid area covered relation. This interaction takes place with an increase in surface stability and a reduction in peptide molecular area (intermolecular interaction). Data suggest a dynamic membrane modulation by which the peptide fine‐tunes its membrane orientation and its lateral stability, depending on the quality (lipid composition) of the interface. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.