In China, there is an old proverb” increase income and reduce expenditure”. There are many ways to increase the expression efficiency of a gene, such as choose a stronger promoter or RBS. Changing the Promoter and RBS is just like “increasing income”. But it is more cost-efficient to increase the expression by reducing expenditure. So, can we increase the expression of a gene by stabilizing its mRNA?
　   In many prokaryotes, We find that RNase E mediated RNA degradation is a main progress in mRNA regulation of RNA level. So, can we stabilize an mRNA by decreasing the degradation? Previous studies revealed that the most important endonuclease for mRNA turnover in E. coli is RNase E. So, if we can inhibit its activity, then our goals would be achieved. It has been reported that mRNA is more stable when it is being translated and they explain it by the ribosome preventing mRNA degradation.



　   Fig.1. 5’-end-dependent mRNA decay in bacteria that contain the endonuclease RNase E or ahomolog thereof. Pyrophosphate removal by RppH generates a 5’-terminal monophosphatethat binds to a discrete pocket on the surface of RNase E, thereby facilitating mRNA cleavage at a downstream location by the active site of that enzyme. In E. coli, RNase E cleavage of primary transcripts can also occur by an alternative, 5’-end-independent mechanism that does not require prior pyrophosphate removal.
　   So, an idea comes to our mind. Can the ribosome work as a barrier, preventing the activation of this enzyme? This is what we have tried to do.