Cryo electron microscopy captures ubiquitin opening the nucleosome August 10, 2018 Dr Ramasubramanian Sudaramoorthy and co-workers have determined the structure of an enzyme that regulates access to DNA bound to a ubiquitinylated nucleosome. This work has been published in the journal eLife. The DNA within the cells of most multi cellular life forms is wrapped around histone proteins, to form disk-like nucleosomes that regulate access to the underlying genetic information. To control DNA wrapping cells use molecular machines known as chromatin remodelling enzymes. Understanding how these machines interact with histone bound DNA has been challenging. To address this Dr Sundarmoorthy established the use of high resolution electron microscopy to characterize molecular structure in Dundee. This technique is revolutionizing study of the protein complexes that underpin cellular function. To his surprise Dr Sundaramoorthy observed that a ubiquitin peptide attached to a histone protein directly bound to DNA that was partially unwrapped by the remodelling enzyme. Dr Sundaramoorthy commented “seeing is believing, and I will not forget the moment I realized ubiquitin was binding to DNA. It immediately opened up new ways of thinking about how attachment of ubiquitin to this histone protein functions in gene regulation. I hope other researchers in Dundee will now be able to apply electron microscopy to characterize the proteins they are working on”. Dr Sundaramoorthy worked closely with Amanda Hughes, David Norman and Tom Owen-Hughes in Dundee and Hassane el-Mkami at University of St Andrews. Image key: DNA – gold; histones – grey; ubiquitin – turquoise; Chd1- enzyme blue
