A simple fusion may shed light on how life evolved on earth

December 19th, 2008 - 3:12 pm ICT by ANI  

Washington, Dec 19 (ANI): By conducting a simple fusion experiment, scientists have taken a major step towards answering one of biology’’s most complex questions: how ancient organic molecules came together to form the basis of life.

In a new study, researchers have shown how ancient RNA joined together to reach a biologically relevant length.

RNA is the single-stranded precursor to DNA, which normally expands one nucleic base at a time and grows sequentially like a linked chain.

But, in the primordial world RNA molecules didn”t have enzymes to catalyse this reaction, and while RNA growth can proceed naturally, the rate would be so slow the RNA could never get more than a few pieces long (for as nucleic bases attach to one end, they can also drop off the other).

A research team led by Ernesto Di Mauro studied if there was some mechanism to overcome this thermodynamic barrier, by incubating short RNA fragments in water of different temperatures and pH.

It was found that under favourable conditions (acidic environment and temperature lower than 70 C), pieces ranging from 10-24 in length could naturally fuse into larger fragments, generally within 14 hours.

Researchers saw that the RNA fragments came together as double-stranded structures then joined at the ends.

The fragments did not have to be the same size, but the efficiency of the reactions was dependent on fragment size (larger is better, though efficiency drops again after reaching around 100) and the similarity of the fragment sequences.

They also noted that this spontaneous fusing, or ligation, would a simple way for RNA to overcome initial barriers to growth and reach a biologically important size; at around 100 bases long, RNA molecules can begin to fold into functional, 3D shapes.

The study is appearing online in JBC. (ANI)

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