Variation in auxin sensing guides AUX/IAA transcriptional repressor ubiquitylation and destruction

Subfunctionalization of duplicated genes (ohnologs) is known to occur through eventual differential gene regulation/expression and sequence divergence. Winkler et al. explore the example of the negative regulators of auxin signaling, AUX/IAA proteins IAA6 and IAA19 and how their divergent structures in the ubiquitinated and unstructured regions flanking the domain II degron differs between the two proteins. It is also interesting that ubiquitination sites have a propensity to appear in unstructured regions of proteins. The structural differences lead to differential lysine ubiquitination and therefore different auxin responses, in degradation rate or signaling. These ohnolog differences lead to differing auxin level sensitivity and responses. Nature Comm. 10.1038/ncomms15706 (OA)