Dr Bj\u00f6rn M. Burmann \u00a9 Fotograf Johan Wingborg<\/figcaption><\/figure>\nIn the Burmann lab, we are making use of the unique capabilities of NMR spectroscopy to study the dynamics of the protein backbone as well as the amino acid sidechains, which is enabling us to get a deep view of the allosteric processes regulating the functionality of proteins. NMR\u2019s unique ability to study a variety of states in an aqueous buffer solution provides direct access to a large variety of important biological processes which are spread over a diverse set of timescales, ranging from nanoseconds to seconds and minutes (see Fig. 1).<\/p>\nFig. 1: Assessing protein dynamics by NMR. A) Local and global motions of proteins can occur on a variety of different time scales. B) Characteristic timeline of motions occurring in proteins and different suitable NMR experiments assessing these different types of protein dynamics<\/figcaption><\/figure>\nThe Tudor domain<\/h3>\n Using these powerful approaches, we recently set out to understand the inherent dynamics of a small classical protein fold, which can be found in all organisms throughout the tree of life, the Tudor domain. A Tudor domain is about ~60 amino acids in size and forms a characteristic barrel-shaped \u00df-strand fold (see Fig. 2). This domain mediates a variety of protein:protein interactions, but differ in their repertoire of interaction partners. In a recent study addressing the dynamics of bacterial Tudor domains, we compared them based on their functional properties; either having a small set of interaction partners (NusG)1<\/sup>, multiple interaction partners (UvrD)2<\/sup>, or metaphoric domain that can change its structure from the classical Tudor domain fold to two helices forming an inhibited state (RfaH)3<\/sup> (see Fig. 2).<\/p>\nFig. 2: Structural overview of the different bacterial Tudor domains discussed. In addition, the structural transition of metamorphic RfaH-Tudor is indicated<\/figcaption><\/figure>\nOur study revealed a fine-tuning of the inherent dynamical properties which could be directly coupled to the functional repertoire of the domain.4<\/sup> Whereas the optimised NusG-Tudor with a defined set of interaction partners revealed the most stable fold of the proteins under study, increasing the functional repertoire for the UvrD-CTD has already shown more flexibility on the slow timescale, i.e. protein loop arrangements on the micro- to millisecond timescale, within the protein domain clearly indicating the need for local adaptations to enhance the binding promiscuity. Our compare-and-contrast study has enabled us to construct a simplified scheme correlating protein dynamics directly to functional repertoire (see Fig. 3).<\/p>\nFig. 3: Schematic representation of the timescale and amplitude of inherent Tudor domain dynamics relating to their functional repertoire. Figure adapted and reproduced from Kawale and Burmann, Structure 20214 under a CC-BY License (Elsevier)<\/figcaption><\/figure>\nShape-shifting properties<\/h3>\n The most interesting finding was for the metamorphic Tudor of RfaH which, in addition to the flexibility in its loop regions, showed throughout the whole domain a large amplitude of motions on the nanosecond timescale indicative of a semi-stable protein fold.<\/p>\n
As the understanding of the underlying driving forces of the structural switches of metamorphic proteins remain largely elusive,5<\/sup> we believe that with our approaches we will be able to elucidate the functional basis of how the remarkable shape-shifting properties of this growing set of proteins can be addressed.<\/p>\n