Insights into protein adaptation to a saturated salt environment from the crystal structure of a halophilic 2Fe-2S ferredoxin

Felix Frolow, Michal Harel, Joel L. Sussman, Moshe Mevarech, Menachem Shoham*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

Abstract

Haloarcula marismortui is an archaebacterium that flourishes in the world's saltiest body of water, the Dead Sea. The cytosol of this organism is a supersaturated salt solution in which proteins are soluble and active. The crystal structure of a 2Fe-2S ferredoxin from H. marismortui determined at 1.9 Å is similar to those of plant-type 2Fe-2S ferredoxins of known structure, with two important distinctions. The entire surface of the protein is coated with acidic residues except for the vicinity of the iron-sulphur cluster, and there is an insertion of two amphipathic helices near the N- terminus. These form a separate hyperacidic domain whose postulated function to provide extra surface carboxylates for solvation. These data and the fact that bound surface water molecules have on the average 40% more hydrogen bonds than in a typical non-halophilic protein crystal structure support the notion that haloadaptation involves better water binding capacity.

Original languageEnglish
Pages (from-to)452-458
Number of pages7
JournalNature Structural Biology
Volume3
Issue number5
DOIs
StatePublished - 1996

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