Bacterial Growth Inhibition Screen (BGIS) identifies a loss-of-function mutant of the DEK oncogene, indicating DNA modulating activities of DEK in chromatin.

The DEK oncoprotein regulates cellular chromatin function via a number of protein-protein interactions. However, the biological relevance of its unique pseudo-SAP/SAP-box domain, which transmits DNA modulating activities in vitro, remains largely speculative. As hypothesis-driven mutations failed to yield DNA binding null (DBN) mutants, we combined random mutagenesis with the Bacterial Growth Inhibition Screen (BGIS) to overcome this bottleneck. Re-expression of a DEK-DBN mutant in newly established human DEK knockout cells failed to reduce the increase in nuclear size as compared to wild type, indicating roles for DEK-DNA interactions in cellular chromatin organisation. Our results extend the functional roles of DEK in metazoan chromatin and highlight the predictive ability of recombinant protein toxicity in E. coli for unbiased studies of eukaryotic DNA modulating protein domains.