Changes in non-core regions stabilise plastocyanin from the thermophilic cyanobacterium Phormidium laminosum.
We report a theoretical investigation on the different stabilities of two plastocyanins. The first one belongs to the thermophilic cyanobacterium Phormidium laminosum and the second one belongs to its mesophilic relative Synechocystis sp. These proteins share the same topology and secondary-structure elements; however, the melting temperatures of their oxidised species differ by approximately 15 K. Long-time-scale molecular dynamics simulations, performed at different temperatures, show that the thermophilic protein optimises a set of intramolecular interactions (interstrand hydrogen bonding, salt bridging and hydrophobic clustering) within the region that comprises the strands beta 5 and beta 6, loop L5 and the helix. This region exhibits most of the differences in the primary sequence between the two proteins and, in addition, it is involved in the interaction with known physiological partners. Further work is in progress to unveil the specific structural features responsible for the different thermal stability of the two proteins.
Muñoz-López
Francisco J
FJ
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y C.S.I.C., Avda. Américo Vespucio, 49, 41092 Seville, Spain.
Raugei
Simone
S
De la Rosa
Miguel A
MA
Díaz-Quintana
Antonio J
AJ
Carloni
Paolo
P
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D000458:Cyanobacteria / Q000737:chemistry*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010970:Plastocyanin / Q000737:chemistry*; D011487:Protein Conformation; D055550:Protein Stability; D013696:Temperature
D001426:Bacterial Proteins; D010970:Plastocyanin