Proline-induced disruption of a transmembrane α-helix in its natural environment

• Published in: Journal of molecular biology Vol. 284; no. 4; pp. 1165 - 1175
• Main Authors: Nilsson, IngMarie, Sääf, Annika, Whitley, Paul, Gafvelin, Guro, Waller, Cecilia, von Heijne, Gunnar
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 11-12-1998
• Subjects: Amino Acid Sequence; Catalytic Domain; Endoplasmic Reticulum - enzymology; Escherichia coli - genetics; Glycosylation; Hexosyltransferases; Lipid Bilayers; Medicin och hälsovetenskap; membrane protein; Membrane Proteins - chemistry; Membrane Proteins - genetics; Models, Molecular; Molecular Sequence Data; Photosynthetic Reaction Center Complex Proteins - chemistry; Photosynthetic Reaction Center Complex Proteins - genetics; proline; Proline - chemistry; Protein Conformation; protein structure; Protein Structure, Secondary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Rhodobacter sphaeroides - chemistry; Rhodobacter sphaeroides - genetics; Transferases - chemistry; transmembrane helix; protein structure; proline; OST; TMHs; Lep; membrane protein; glycosylation; transmembrane helix; MGD; ER
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1006/jmbi.1998.2217

α-Helix formation in globular proteins has been studied both theoretically and experimentally for decades, while a lack of both high-resolution structures and suitable experimental techniques has hampered the study of helices in membrane proteins. We have developed a new experimental approach, glycosylation mapping, where the active site of the lumenally exposed endoplasmic reticulum enzyme oligosaccharyl transferase is used as a point of reference against which the position of a transmembrane segment in the membrane can be measured. Here, we report an initial analysis of the helix-breaking properties of proline residues inserted in a transmembrane helix. We find that proline residues can break a transmembrane helix, but only when inserted near the end, and only when the helix is sufficiently long. The glycosylation mapping technique may be generally useful for determining the position of transmembrane helices in the membrane.