Energetic selection of topology in ferredoxins.
| Autor: | J Dongun Kim, Agustina Rodriguez-Granillo, David A Case, Vikas Nanda, Paul G Falkowski |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | PLoS Computational Biology, Vol 8, Iss 4, p e1002463 (2012) |
| Druh dokumentu: | article |
| ISSN: | 1553-734X 1553-7358 51036142 |
| DOI: | 10.1371/journal.pcbi.1002463 |
| Popis: | Models of early protein evolution posit the existence of short peptides that bound metals and ions and served as transporters, membranes or catalysts. The Cys-X-X-Cys-X-X-Cys heptapeptide located within bacterial ferredoxins, enclosing an Fe₄S₄ metal center, is an attractive candidate for such an early peptide. Ferredoxins are ancient proteins and the simple α+β fold is found alone or as a domain in larger proteins throughout all three kingdoms of life. Previous analyses of the heptapeptide conformation in experimentally determined ferredoxin structures revealed a pervasive right-handed topology, despite the fact that the Fe₄S₄ cluster is achiral. Conformational enumeration of a model CGGCGGC heptapeptide bound to a cubane iron-sulfur cluster indicates both left-handed and right-handed folds could exist and have comparable stabilities. However, only the natural ferredoxin topology provides a significant network of backbone-to-cluster hydrogen bonds that would stabilize the metal-peptide complex. The optimal peptide configuration (alternating α(L),α(R)) is that of an α-sheet, providing an additional mechanism where oligomerization could stabilize the peptide and facilitate iron-sulfur cluster binding. |
| Databáze: | Directory of Open Access Journals |
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