Biology subjects

Roguev, A.

Publications and source records attributed to Roguev, A..

2 recordsLinked to original sources

bioRxiv2018

The Set1 complex is dimeric and acts with Jhd2 demethylation to convey symmetrical H3K4 trimethylation

Epigenetic modifications can maintain or alter the inherent symmetry of the nucleosome however the mechanisms that deposit and/or propagate symmetry or asymmetry are not understood. Here we report that yeast Set1C/COMPASS is dimeric and consequently symmetrically trimethylates histone 3 lysine 4 (H3K4me3) on promoter nucleosomes. Mutation of the dimer interface to make Set1C monomeric abolished H3K4me3 on most promoters. The most active promoters, particularly those involved in the oxidative phase of the yeast metabolic cycle, displayed H3K4me2, which is normally excluded from active promoters, and a subset of these also displayed H3K4me3. In wild-type yeast, deletion of the sole H3K4 demethylase, Jhd2, has no effect. However in monomeric Set1C yeast, Jhd2 deletion increased H3K4me3 levels on the H3K4me2 promoters. Notably, the association of Set1C with the elongating polymerase was not perturbed by monomerisation. These results imply that symmetrical H3K4 methylation is an embedded consequence of Set1C dimerism and that Jhd2 demethylates asymmetric H3K4me3. Consequently, rather than methylation and demethylation acting in opposition as logic would suggest, a dimeric methyltransferase and monomeric demethylase co-operate to eliminate asymmetry and focus symmetrical H3K4me3 onto selected nucleosomes. This presents a new paradigm for the establishment of epigenetic detail.

cell biology↗

bioRxiv2017

Protein Moonlighting Revealed by Non-Catalytic Phenotypes of Yeast Enzymes

A single gene can partake in several biological processes, and therefore gene deletions can lead to different--sometimes unexpected--phenotypes. However, it is not always clear whether such pleiotropy reflects the loss of a unique molecular activity involved in different processes or the loss of a multifunctional protein. Here, using Saccharomyces cerevisiae metabolism as a model, we systematically test the null hypothesis that enzyme phenotypes depend on a single annotated molecular function, namely their catalysis. We screened a set of carefully selected genes by quantifying the contribution of catalysis to gene-deletion phenotypes under different environmental conditions. While most phenotypes were explained by loss of catalysis, 30% could be readily complemented by a catalytically-inactive enzyme. Such non-catalytic phenotypes were frequent in the Alt1 and Bat2 transaminases and in the isoleucine/valine-biosynthetic enzymes Ilv1 and Ilv2, suggesting novel \"moonlighting\" activities in these proteins. Furthermore, differential genetic-interaction profiles of gene-deletion and catalytic mutants indicated that ILV1 is functionally associated to regulatory processes, specifically to chromatin modification. Our systematic study shows that gene-loss phenotypes and their genetic interactions are frequently not driven by the loss of an annotated catalytic function, underscoring the moonlighting nature of cellular metabolism.

genetics↗