MicroRNAs (miRNAs) -- tiny strands of non-protein-coding RNAs -- start off as long strands of precursor miRNAs. These long strands get chopped up by a special kind of machinery, the "Microprocessor" complex, to transform them into their shorter functional form. The resulting miRNAs bind to messenger RNA (mRNAs) molecules, inhibiting their protein production capacity and thus regulating the levels of hundreds of different proteins.
But the Microprocessor complex can also cut up other forms of RNA, such as mRNAs, which sometimes generate a transient structure that resembles the target site of miRNAs. Cleaving the wrong RNAs could prove disastrous for the organism.
In a paper recently published in Nature Structural and Molecular Biology, Dr. Eran Hornstein, Prof. Naama Barkai and former Ph.D. students Drs. Omer Barad and Mati Mann of the Molecular Genetics Department focus on understanding how the Microprocessor machinery balances the interplay between efficiency and specificity in the production of miRNAs. "On the one hand, it should not be overly efficient, as this may come at the cost of also cleaving unwanted nonspecific RNA substrates. On the other hand, it should not be too 'picky' because exaggerated specificity comes with the risk of not sufficiently processing genuine miRNAs," says Hornstein.
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