Post-transcriptional regulation, why?

[Michael L. Sullivan]

>
>Yes, I do understand that it would be advantageous in these cases. 
>But what about constituvely expressed E.coli proteins that the cell 
>needs to have at a constant level? Why would evolution design 
>sub-optimal translation efficiency of these? Why not just have a 
>weak promotor and let translation be optimal? It seems to be a waste 
>of energy to make mRNA which will be degraded before translated 
>because of inefficient translation.
>
>Trond Erik

One answer I think is that it's sometimes hard to know that something 
really is needed at a constant level.  Researchers often don't look 
at every condition, and the lab is hardly the real world where many 
organisms are faced with constantly changing environments.  So it's 
hard to know whether some particular level of regulation is *really* 
wasteful or not.  One thing is certain: at worst, these seemingly 
wasteful mechanisms are on balance not detrimental, otherwise they 
would be selected against by evolution.  More than likely they confer 
an advantage of some sort.

Mike
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Michael L. Sullivan, 
Ph.D                                                            
U.S. Dairy Forage Research Center
1925 Linden Drive West
Madison WI, 53706

(608) 264-5144 Phone
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