Protein-maker functions like an editor!

January 8th, 2009 - 5:05 pm ICT by IANS  

Washington, Jan 8 (IANS) The enzyme machine that translates a cell’s DNA code into the proteins of life is amazing as an ‘editorial perfectionist’.Researchers at the Johns Hopkins University School of Medicine (JHUSM) have discovered a new “proofreading step” in which the suite of translational tools called the ribosome recognises errors, just after making them, and ‘deleting’ them just as definitively.

To carry out the business of life, ribosome exerts far tighter quality control over its precious protein products which are the workhorses of the cell, said the research published this week in ‘Nature’.

“If there is any miscoding, the ribosome cuts the bond and aborts the protein-in-progress, end of story,” said Rachel Green, a professor of molecular biology and genetics at the university. “There’s no second chance,” she added.

The bacterial ribosomes reacted to the lab-induced chemical errors. Green and her team was surprised to see that protein-making process didn’t proceed as usual.

“We noticed that one mistake on the ribosomal assembly line begets another and this compounding of errors leads to the partially finished protein being tossed into the cellular trash,” Green said.

The ribosome drops the error-laden proteins 10,000 times faster than it would normally release error-free proteins, a rate of destruction that Green says is “shocking” and reveals just how much of a stickler the ribosome is about high-fidelity protein synthesis, said the JHUSM release.

“The cell is a wasteful system since it makes something and then says, forget it, throw it out,” Green conceded. “But the waste is worth it to increase fidelity. There are places in life where fidelity matters.” she added.

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