Type II transmembrane domain hydrophobicity dictates the cotranslational dependence for inversion
2014 (English)In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 25, no 21, 3363-3374 p.Article in journal (Refereed) Published
Membrane insertion by the Sec61 translocon in the endoplasmic reticulum (ER) is highly dependent on hydrophobicity. This places stringent hydrophobicity requirements on transmembrane domains (TMDs) from single-spanning membrane proteins. On examining the single-spanning influenza A membrane proteins, we found that the strict hydrophobicity requirement applies to the N-out-C-in HA and M2 TMDs but not the N-in-C-out TMDs from the type II membrane protein neuraminidase (NA). To investigate this discrepancy, we analyzed NA TMDs of varying hydrophobicity, followed by increasing polypeptide lengths, in mammalian cells and ER microsomes. Our results show that the marginally hydrophobic NA TMDs (Delta G(app) > 0 kcal/mol) require the cotranslational insertion process for facilitating their inversion during translocation and a positively charged N-terminal flanking residue and that NA inversion enhances its plasma membrane localization. Overall the cotranslational inversion of marginally hydrophobic NA TMDs initiates once similar to 70 amino acids past the TMD are synthesized, and the efficiency reaches 50% by similar to 100 amino acids, consistent with the positioning of this TMD class in type II human membrane proteins. Inversion of the M2 TMD, achieved by elongating its C-terminus, underscores the contribution of cotranslational synthesis to TMD inversion.
Place, publisher, year, edition, pages
2014. Vol. 25, no 21, 3363-3374 p.
Biophysics Biochemistry and Molecular Biology
Research subject Biochemistry
IdentifiersURN: urn:nbn:se:su:diva-110182DOI: 10.1091/mbc.E14-04-0874ISI: 000344236100019OAI: oai:DiVA.org:su-110182DiVA: diva2:787511