1. Asn- and Asp-mediated interactions between transmembrane helices during translocon-mediated membrane protein assembly
- Author
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Meindl-Beinker, Nadja M, Lundin, Carolina, Nilsson, Ingmarie, White, Stephen H, and von Heijne, Gunnar
- Subjects
endoplasmic reticulum ,helix-helix interaction ,membrane protein assembly ,Sec61 ,transmembrane helix - Abstract
Inter-helix hydrogen bonding involving asparagine (Asn, N), glutamine (Gin, Q), aspartic acid (Asp, D) or glutamic acid (Glu, E) can drive efficient di- or trimerization of transmembrane helices in detergent micelles and lipid bilayers. Likewise, Asn-Asn and Asp-Asp pairs can promote the formation of helical hairpins during translocon-mediated membrane protein assembly in the endoplasmic reticulum. By in vitro translation of model integral membrane protein constructs in the presence of rough microsomes, we show that Asn- or Asp-mediated interactions with a neighbouring transmembrane helix can enhance the membrane insertion efficiency of a marginally hydrophobic transmembrane segment. Our observations suggest that inter-helix hydrogen bonds can form during Sec61 translocon-assisted insertion and thus could be important for membrane protein assembly.
- Published
- 2006