Protein Knotting

Note: This article is an extension of the Protein Folding Problemplugin-autotooltip__plain plugin-autotooltip_bigProtein structuring

Genes set the order that amino acids (the chemical building blocks of proteins) appear in the proteins which they code for. But, working from the gene, the form which the protein's 3-D structure will take cannot as yet be predicted. The extremely complex shapes in which the protein 'folds' has a profound effect on the properties it has within an organism.

Knotting in proteins was once considered exceedingly rare. However, systematic analyses of solved protein structures over the last two decades have demonstrated the existence of many deeply knotted proteins.
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Systematic reviews of the ever-growing Protein Data Bank (PDB) and the development of specialized servers for detecting protein knots have led to the identification of hundreds of knotted proteins, and it is now generally accepted that a small but significant fraction of proteins contains knots. However, exactly how and why such knots form are still unknown."

Source : Topological descriptions of protein folding, PNAS, April 2019

So far, five distinct types of knots have been discovered. Given that the physical shape of a protein is crucial to its biological functions, it's likely that the knotting will have a profound impact on its properties.

Also see : Intrinsically disordered proteinsplugin-autotooltip__plain plugin-autotooltip_bigIntrinsically disordered proteins

Before year 2000, it was generally assumed that the way in which proteins 'folded' was the sole key to understanding their function in life-systems. (See :Protein structuring ). Since then, it has been shown that many proteins do not entirely 'fold up' - leaving large sections of the protein chain as coils which appear to be random. This can profoundly affect the way in which they function and influence cellular systems.

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