Effects of core-packing on the structure, function, and mechanics of a four-helix-bundle protein ROP
Ceruso MA, Grottesi A, Di Nola A
PROTEINS-STRUCTURE FUNCTION AND GENETICS
36 (4): 436-446 SEP 1 1999

FULL TEXT

Abstract:

The effects of core-packing on the structure, function and mechanics of the RNA-binding 4-helix-bundle Rop have been studied by molecular dynamics simulations. The structural, dynamical and geometrical properties of the Rop homodimer, (formed by the antiparallel juxtaposition of two helix-turn-helix motifs), have been compared with those of three protein variants described by Munson et al. (Protein Sci, 5:1584-1593, 1996), where the core of the native protein has been systematically repacked using a two-amino acid alphabet: Ala(2)Leu(2)-8, Ala(2)Leu(2)-8-rev, and Leu(2)Ala(2)-8. The results showed that it was possible to readily distinguish the inactive protein Leu(2)Ala(2)-8 from the other functionally active systems based on tertiary and quaternary structure criteria. Structural properties such as native secondary structure content did not correlate with biological activity. Biological activity was related in part to the relative arrangement of the residues within the binding site. But, more global aspects, related to the overall topology of the helical bundle, accounted for the small functional differences between Ala(2)Leu(2)-8 and Ala(2)Leu(2)-8-rev. Mechanically, the 4-helix-bundle absorbed core mutations by altering the local structure at the sequence termini and in the turns that join the two helices of each monomer, and by changing the overall orientation and separation of the extremely rigid helices. Proteins 1999;36:436-446. (C) 1999 Wiley-Liss, Inc.

Author Keywords:

protein structure, molecular dynamics, Rom, hydrophobic, coiled-coil, alpha-helix, RNA-binding, structure-function relationships

KeyWords Plus:

4-STRANDED COILED COILS, COLI RIBONUCLEASE HI, HYDROPHOBIC CORE, BACKBONE FLEXIBILITY, SECONDARY STRUCTURE, MOLECULAR-DYNAMICS, DESIGN, STABILITY, MUTANTS, ANTIPARALLEL

Addresses:

Ceruso MA, Univ Rome La Sapienza, Dept Chem, POB 34 Roma 62,Ple Aldo Moro 5, I-00185 Rome, Italy
Univ Rome La Sapienza, Dept Chem, I-00185 Rome, Italy