Protein translocation across the endoplasmic reticulum membrane in cold-adapted organisms
| Autor: | Wiep Scheper, Margaret R. Lindsay, James Logue, Nelyn Soto, Karin Römisch, C.-H. Christina Cheng, Nicola Collie |
|---|---|
| Přispěvatelé: | Genome Analysis |
| Jazyk: | angličtina |
| Rok vydání: | 2003 |
| Předmět: |
Sec61
Vesicle-associated membrane protein 8 DNA Complementary Saccharomyces cerevisiae Proteins Molecular Sequence Data Saccharomyces cerevisiae Biology Endoplasmic Reticulum Models Biological Fungal Proteins Microsomes Membrane fluidity Animals Amino Acid Sequence Secretory pathway Sequence Homology Amino Acid Endoplasmic reticulum Fishes Temperature Membrane Proteins Membrane Transport Proteins Intracellular Membranes Cell Biology Lipids Transmembrane protein Protein Structure Tertiary Cell biology Cold Temperature Cryptococcus Microscopy Electron Protein Transport Transmembrane domain Secretory protein Liver Biochemistry Microsomes Liver RNA Protein Processing Post-Translational SEC Translocation Channels |
| Zdroj: | Journal of cell science, 116(Part 14), 2875-2883. Company of Biologists Ltd |
| ISSN: | 0021-9533 |
| Popis: | Secretory proteins enter the secretory pathway by translocation across the membrane of the endoplasmic reticulum (ER) via a channel formed primarily by the Sec61 protein. Protein translocation is highly temperature dependent in mesophilic organisms. We asked whether the protein translocation machinery of organisms from extremely cold habitats was adapted to function at low temperature and found that post-translational protein import into ER-derived microsomes from Antarctic yeast at low temperature was indeed more efficient than into mesophilic yeast microsomes. Analysis of the amino-acid sequences of the core component of the protein translocation channel, Sec61p, from Antarctic yeast species did not reveal amino-acid changes potentially adaptive for function in the cold, because the sequences were too divergent. We therefore analyzed Sec61alpha (vertebrate Sec61p) sequences and protein translocation into the ER of Antarctic and Arctic fishes and compared them to Sec61alpha and protein translocation into the ER of temperate-water fishes and mammals. Overall, Sec61alpha is highly conserved amongst these divergent taxa; a number of amino-acid changes specific to fishes are evident throughout the protein, and, in addition, changes specific to cold-water fishes cluster in the lumenal loop between transmembrane domains 7 and 8 of Sec61alpha, which is known to be important for protein translocation across the ER membrane. Secretory proteins translocated more efficiently into fish microsomes than into mammalian microsomes at 10 degrees C and 0 degrees C. The efficiency of protein translocation at 0 degrees C was highest for microsomes from a cold-water fish. Despite substantial differences in ER membrane lipid composition, ER membrane fluidity was identical in Antarctic fishes, mesophilic fishes and warm-blooded vertebrates, suggesting that membrane fluidity, although typically important for the function of the transmembrane proteins, is not limiting for protein translocation across the ER membrane in the cold. Collectively, our data suggest that the limited amino-acid changes in Sec61alpha from fishes may be functionally significant and represent adaptive changes that enhance channel function in the cold. |
| Databáze: | OpenAIRE |
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