Nonribosomal proteins associated with affinity-purified 50S particles. (A) Shown are the predicted stoichiometries of each nonribosomal protein detected at a level of >0.01 for either control (blue) or mutant (orange) particles. Bars represent the mean ± SEM of three biological replicates. Inset shows the collective abundance of all nonribosomal proteins bound. Units represent ribosome stoichiometry, where 1.0 corresponds to the median r-protein value. Thus, isolated control subunits contain ∼1.5 nonribosomal proteins on average, while isolated ΔSRL particles contain ∼2.7. Based on a two-tailed paired t-test, P < 0.05. (B) For the same 41 nonribosomal proteins, fold enrichment (ΔSRL/control) values are shown. Data represent the quotient of two means ± standard error. For IlvC, ArgG, and NuoF, no protein was detected in any of the control sample replicates, so an enrichment value of 100 was assigned arbitrarily.
