Intrinsically Disordered Proteins
Intrinsically disordered proteins (IDPs) are proteins that lack a stable 3-dimensional structure. This means that they have many possible confirmations, the collection of these possible confirmations is called the proteins ensemble. Despite their lack of consistent structure, IDPs and proteins containing intrinsically disordered regions (IDRs) play crucial roles in many biological processes.
A proteins structure is classified in three (or sometimes four) categories. Primary structure refers to the order of amino acids in a protein, secondary structure refers to interactions between the back bone of the amino acids, and tertiary structure refers to interactions due to the unique sequence of amino acids in a protein. Most proteins have a single stable tertiary structure. Intrinsically disordered proteins have several possible tertiary structures that they may be in at any given moment. The collection of possible structures that an IDP can have is called its ensemble.
IDPs, such as those found in tardigrades called late embryogenesis abundant (LEA) proteins, and heat resistant obscure proteins have been linked with the ability of some organisms to survive extreme stresses, such as freezing and drying. Despite this, we still know relatively little about how IDPs and IDRs function to promote stress tolerance.
Owing to their unstructured nature IDPs do not follow the structure to function paradigm that well-folded proteins do. Instead, a sequence to function paradigm is considered more accurate for IDPs. However, because of their pliable nature, IDP global and local dynamics are also strongly influenced by their environment. During extreme abiotic stresses, this influence of environment on IDP function is likely exaggerated. Thus, we are seeking to establish general rules for a sequence + environment to function paradigm for stress tolerance IDPs. Click here to learn more about sequence and environment interactions.