1f4m
From Proteopedia
P3(2) CRYSTAL STRUCTURE OF ALA2ILE2-6, A VERSION OF ROP WITH A REPACKED HYDROPHOBIC CORE AND A NEW FOLD.
Overview
BACKGROUND: Rop is an RNA binding, dimeric, four-helix bundle protein with a well-defined, regular hydrophobic core ideally suited for redesign studies. A family of Rop variants in which the hydrophobic core was systematically redesigned has previously been created and characterized. RESULTS: We present a structural and thermodynamic analysis of Ala2Ile2-6, a variant of Rop with an extensively redesigned hydrophobic core. The structure of Ala2Ile2-6 reveals a completely new fold formed by a conformational "flip" of the two protomers around the dimeric interface. The free-energy profile of Ala2Ile2-6 is also very different from that of wild-type Rop. Ala2Ile2-6 has a higher melting temperature than Rop, but undergoes a slightly smaller free-energy change on unfolding. CONCLUSIONS: The structure of Ala2Ile2-6, along with molecular modeling results, demonstrate the importance of tight packing of core residues and the adoption of favorable core side chain rotamer values in determining helix-helix interactions in the four-helix bundle fold. Structural disorder at the N and C termini of Ala2Ile2-6 provides a basis for the large differences in the enthalpy and entropy of Ala2Ile2-6 folding compared with wildtype Rop.
About this Structure
1F4M is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Dramatic structural and thermodynamic consequences of repacking a protein's hydrophobic core., Willis MA, Bishop B, Regan L, Brunger AT, Structure. 2000 Dec 15;8(12):1319-28. PMID:11188696 Page seeded by OCA on Fri May 2 15:53:33 2008
