Värd: Jonas Barandun, MIMS group leader, SciLifelab National Fellow, Institutionen för molekylärbiologi
Abstrakt: Faithful protein synthesis is ensured by extensive quality control checkpoints using components of the translational machinery. However, the implications of defective ribosome assembly on protein synthesis and the associated translation quality control mechanisms in bacteria remain grossly unaddressed. In this study, using E. coli as a model organism we show that premature ribosomes evade scrutiny of cognate start Codon by initiation factors during translation initiation. Resultantly the defective ribosomes make way into the translation cycle with severely compromised decoding and protein synthesis capabilities. The enfeebled binding of premature ribosomes to initiation factors also licenses the rapid conversion of the 30S (pre) initiation complex to 70S initiation complex. Overall, our work highlights that a mass balance deficit between premature ribosomes and initiation factors steers the entry of premature ribosomes into the translation cycle.