Elucidating the function of the unknown Escherichia coli GTPase YjeQ through genetic interactions

The protein YjeQ is a small GTPase that associates with the 30S ribosomal subunit. The slow steady state GTPase activity of YjeQ of 10 h −1 is stimulated 160 fold by this interaction, implicating the ribosome as the site of YjeQ function in the cell. Although dispensable in both Escherichia coli and Bacillus subtilis , strains lacking this protein are severely comprised for growth. Additionally, we have shown that this protein is a virulence determinant in a Staphylococcus aureus mouse infection model, implicating it as a potential target for the development of new antimicrobial agents. In this study we are looking at the genetic interactions of yjeQ to more precisely determine its role in the cell. Two methods were used to identify genetic interactions with yjeQ . The first was a screen of overexpression strains for correction of the yjeQ deletion slow growth phenotype. Using this method all essential E. coli genes were screened as well as 40 non‐essential translation related genes. A number of suppressors were identified, with one third functioning in translation or ribosome biogenesis. The suppressors were further screened for mechanism of suppression, and infB , era , and glnS were found to partially correct a ribosome defect associated with yjeQ deletion. As a second method to identify genetic interactions with yjeQ , double deletion strains were created with yjeQ and the non‐essential translation related genes. These double deletions were characterized for growth and implicate a number of genes as functionally related to yjeQ . Using this data we are creating a network of genes that interact with yjeQ and if they function up‐ or downstream in the cell. This work was funded by CIHR.