Abiotic Stress Adaptation: Protein Folding Stability and Dynamics - Abiotic Stress: Plant Responses and Applications in Agriculture - page 4

aggregation [5]. Folded proteins are generally much less prone to aggregation and degrada‐
tion but partially unfolded or intrinsically disordered regions of proteins can confer func‐
tional advantages, as they allow efficient interaction with binding partners and provide a
mechanism for the regulation of cellular processes. Protein dynamics, meaning structural or
conformational change with time, are an essential part of regulation of biological activity.
Figure 1. Protein folding involving a partially folded intermediate state. The two transition states (TS1, TS2) are sepa‐
rated by a metastable intermediate (I*), modified from [6, 7]. The driving force for protein folding is the search for
lower free energy states, separated by free energy barriers. The free energy of a protein in solution is highly depend‐
ent on temperature, pressure and solvent conditions
Many cellular processes are coupled to protein folding and unfolding, a process that is high‐
ly sensitive to rapid changes in environmental conditions such as denaturant concentration,
temperature or pH. In determining the conformational properties of proteins, it is therefore
important to include solvent and co-solvent conditions.
Protein conformation and activity can differ markedly between diluted and crowded envi‐
ronments. The diverse and highly specific function of proteins is a consequence of their so‐
phisticated, individual surface pattern regarding shape, charge and hydrophobicity that is a
consequence of the three-dimensional structure of polypeptide chains. The stability of pro‐
teins results from a number of counteracting enthalpic and entropic contributions. Native
states represent the most stable conformation under equilibrium. This does not necessarily
mean that protein function is restricted to well-defined folded states. Internal dynamics play
an important role in protein function. In vivo folding, catalytic function, transport and degra‐
dation of proteins all involve transitions between different conformations. Locally unfolded
or disordered regions of a protein allow efficient interaction with binding partners and thus
the regulation of cellular mechanisms. Identifying and defining the rules for protein folding
and unfolding is fundamental for our understanding how living systems cope with abiotic
stresses. Advanced experimental methods continue to be developed to elucidate the sheer
complexity of protein folding and unfolding and the mechanisms of preserving functional
folds under stress conditions.