Fig. 6

Schematic diagram of translational ER and protein synthesis of T3SS under nutrition-limited conditions. A Translational ER was negatively correlated with nutrition conditions. Under rich nutrition conditions, translational ER of T3SS protein was almost completely ceased. Under 0.5× rich conditions, 3× and 2× T3SS-inducing conditions, translational ER of T3SS protein increased but at a low level. Under 1× T3SS-inducing conditions, translational ER was high to support the efficient protein synthesis. Under 0.5× T3SS-inducing conditions, translational ER was higher than that under 1× T3SS-inducing conditions, but the final protein production was unstable. Under 0.25× T3SS-inducing conditions, translational ER dropped by 95%. B Translational ER was negatively correlated with culture time under 1× T3SS-inducing conditions. At 0–30/40 min of induction, reduced EF-Tu, Ts and incorrect insertions of amino acid caused by increased charged tRNAs led to the descending translational ER of T3SS. At 30/40–60 min of induction, degradation of tRNAs and reduced EF-Tu and Ts resulted in the descending translational ER of T3SS. The expression levels of T3SS regulators, effectors and structural protein gradually increased within 0–6 h of induction