Structure-function relationships (Using Discovery Studio)

1. Structure-function relationships(Using Discovery Studio) In an attempt to understand the requirements for maintaining life at high salinity at the molecular level, we will look at the structure of the protein 2Fe-2S ferredoxinfrom halobacterium, which lives in the Dead Sea, the saltiest environment on earth. Proteins in the cytosol of this organism are active at a supersaturated salt concentration (4 M KCl and many other salts), whereas 'normal' proteins in non-halophilic cells would precipitate and cease to function under these conditions.In this exercise we will compare two homologous 2Fe-2S ferredoxin proteins from two different organisms: 1DOI from H.marismortui, a halobacterium (Swissprot: P00217). 1FRD from C. anabaena, a non-halophiliccyanobacterium (Swissprot: P11053).

2. Composition table in percent for the complete database of Swiss-Prot • ProtParam tool http://web.expasy.org/protparam/ Compare the amino-acid composition of the halophilic protein to the table given. This table represents the average amino-acid composition of all swiss-prot proteins, mostly from mesophils. What is the significant difference? Which amino-acids appear more in the halophilic protein sequence? To which chemical-physical group do these amino-acids belong? Where would you expect to find these amino-acids in the protein structure?