Abstract
New experimental findings continue to challenge our understanding of protein allostery. Recent deep mutational scanning study showed that allosteric hotspots in the tetracycline repressor (TetR) and its homologous transcriptional factors are broadly distributed rather than spanning well-defined structural pathways as often assumed. Moreover, hotspot mutation-induced allostery loss was rescued by distributed additional mutations in a degenerate fashion. Here, we develop a two-domain thermodynamic model for TetR, which readily rationalizes these intriguing observations. The model accurately captures the in vivo activities of various mutants with changes in physically transparent parameters, allowing the data-based quantification of mutational effects using statistical inference. Our analysis reveals the intrinsic connection of intra- and inter-domain properties for allosteric regulation and illustrate epistatic interactions that are consistent with structural features of the protein. The insights gained from this study into the nature of two-domain allostery are expected to have broader implications for other multidomain allosteric proteins.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
In this revised version, we've added more discussions about the selection criteria of mutations for analysis and the simplicity of the two-domain model (see the added section 7 and 8 of the supplementary file and Table 1 of main text). We've also added an intuitive explanation of Equation 1 in the main text, as well as more detailed discussions about the intrinsic difficulty of precise inference of large values with our model (see the second subsection of Results and the added Table 2 in the main text, and the second subsection of section 3 of the supplementary file). The error in the third row of Figure 3A is corrected.
