TY - JOUR KW - Protein Folding KW - molecular dynamics KW - Protein Engineering KW - Armadillo Domain Proteins KW - repeat proteins KW - spontaneous assembly AU - R. P. Watson AU - M. T. Christen AU - C. Ewald AU - F. Bumbak AU - C. Reichen AU - M. Mihajlovic AU - E. Schmidt AU - P. Güntert AU - A. Caflisch AU - A. Plückthun AU - O. Zerbe AB -

Repeat proteins are built of modules, each of which constitutes a structural motif. We have investigated whether fragments of a designed consensus armadillo repeat protein (ArmRP) recognize each other. We examined a split ArmRP consisting of an N-capping repeat (denoted Y), three internal repeats (M), and a C-capping repeat (A). We demonstrate that the C-terminal MA fragment adopts a fold similar to the corresponding part of the entire protein. In contrast, the N-terminal YM2 fragment constitutes a molten globule. The two fragments form a 1:1 YM2:MA complex with a nanomolar dissociation constant essentially identical to the crystal structure of the continuous YM3A protein. Molecular dynamics simulations show that the complex is structurally stable over a 1 μs timescale and reveal the importance of hydrophobic contacts across the interface. We propose that the existence of a stable complex recapitulates possible intermediates in the early evolution of these repeat proteins.

BT - Structure C1 - 0187 DA - 2014 Jul 8 DO - 10.1016/j.str.2014.05.002 IS - 7 J2 - Structure LA - eng M3 - Research Article N2 -

Repeat proteins are built of modules, each of which constitutes a structural motif. We have investigated whether fragments of a designed consensus armadillo repeat protein (ArmRP) recognize each other. We examined a split ArmRP consisting of an N-capping repeat (denoted Y), three internal repeats (M), and a C-capping repeat (A). We demonstrate that the C-terminal MA fragment adopts a fold similar to the corresponding part of the entire protein. In contrast, the N-terminal YM2 fragment constitutes a molten globule. The two fragments form a 1:1 YM2:MA complex with a nanomolar dissociation constant essentially identical to the crystal structure of the continuous YM3A protein. Molecular dynamics simulations show that the complex is structurally stable over a 1 μs timescale and reveal the importance of hydrophobic contacts across the interface. We propose that the existence of a stable complex recapitulates possible intermediates in the early evolution of these repeat proteins.

PY - 2014 SP - 985 EP - 995 T2 - Structure TI - Spontaneous self-assembly of engineered armadillo repeat protein fragments into a folded structure VL - 22 SN - 1878-4186 ER -