Did 'Midwife Molecule' Assemble First Life On Earth?

Forming a double helix prevents the RNA from going round in circles
(Image: Laguna Design/SPL)

From New Scientist:

The primordial soup that gave birth to life on EarthMovie Camera may have had an extra, previously unrecognised ingredient: a "molecular midwife" that played a crucial role in allowing the first large biomolecules to assemble from their building blocks.

The earliest life forms are thought by many to have been based not on DNA but on the closely related molecule RNA, because long strands of RNA can act as rudimentary enzymes. This would have allowed a primitive metabolism to develop before life forms made proteins for this purpose.

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Biologists Discover Motor Protein That Rewinds DNA

The enzyme HARP "rewinds" sections of the double-stranded DNA molecule that become unwound, like the tangled ribbons from a cassette tape in DNA "bubbles" that prevent critical genes from being expressed. (Credit: James Kadonaga, UCSD)

From Science Daily:

ScienceDaily (Nov. 2, 2008) — Two biologists at the University of California, San Diego have discovered the first of a new class of cellular motor proteins that “rewind” sections of the double-stranded DNA molecule that become unwound, like the tangled ribbons from a cassette tape, in “bubbles” that prevent critical genes from being expressed.

“When your DNA gets stuck in the unwound position, your cells are in big trouble, and in humans, that ultimately leads to death” said Jim Kadonaga, a professor of biology at UCSD who headed the study. “What we discovered is the enzyme that fixes this problem.”

The discovery represents the first time scientists have identified a motor protein specifically designed to prevent the accumulation of bubbles of unwound DNA, which occurs when DNA strands become improperly unwound in certain locations along the molecule.

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