Probing the molecular function of RecQ4 in human Genome Integrity
Biochemistry
Final Report Abstract
In this project we aimed to extend our knowledge on RecQ4 by structurally characterizing the CTD and exploring the DNA substrate and protein interaction space. Unfortunately, our attempts to structurally characterize the highly important C-terminal domain of RecQ4 were not successful. However, we were able to show the importance of the C-terminal a-helices and based on a very recent alpha-fold model we will be able to continue these studies to decipher the importance of specific residues within this domain and how they are involved in the enzymatic activity of the protein. In addition, we show that the RecQ4 substrate spectrum goes beyond the classical 3’ overhang substrates towards physiologically more relevant substrates like holiday junctions. This newly characterized function requires further investigations but underscores the importance of this enzyme in maintaining genome stability. Lastly, we successfully identified a so far uncharacterized protein interaction of RecQ4 with PCNA and deciphered the binding interface. Interestingly, this interaction does not involve the anticipated PIP box towards the N-terminus of the RecQ4 protein but a region further downstream, which nevertheless seems to interact with PCNA within the “classical” PIP binding pocket. Overall, this work led to highly important insights into RecQ4 function, substrate specificity and binding partners that will spark new studies to further investigate these important findings.
