Proteome-wide Capture of Co-translational Protein Dynamics in Bacillus subtilis Using TnDR, a Transposable Protein-Dynamics Reporter.

Dynamic protein maturation, such as localization, folding, and complex formation, can occur co-translationally. To what extent do nascent polypeptides engage in the co-translational dynamics to produce the functional proteome's complement? We address this question using a protein-dynamics reporter (DR) module comprising a force-sensitive arrest sequence (Bacillus subtilis MifM) followed in frame by LacZ. An engineered transposon, TnDR, carrying DR, is transposed into the B. subtilis chromosome to create translational fusions between N-terminal regions of proteins and the C-terminal DR module. By looking for LacZ+ colonies, we identify hundreds of proteins that cancel the elongation arrest, most probably reflecting their ability to initiate the maturation/localization process co-translationally. Case studies identify B. subtilis proteins that initiate assembly with a partner molecule before completion of translation. These results suggest that cotranslational maturation is a frequently occurring event in protein biogenesis.