Scientists help find new kind of molecular motor

Scientists help find new kind of molecular motor

Subject : Science and technology

Section: Health

Context:

An international team of researchers, including from the National Centre for Biological Sciences (NCBS), Bengaluru, has reported a new kind of molecular motor.

Concept:

• Cells have a fascinating feature to neatly organize their interior by using tiny protein machines called molecular motors that generate directed movements.
• Most of them use a common type of fuel, a kind of chemical energy, called ATP to operate.
• Now researchers from the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), the Cluster of Excellence Physics of Life (PoL) and the Biotechnology Center (BIOTEC) of the TU Dresden in Dresden, Germany, and the National Centre for Biological Sciences (NCBS) in Bangalore, India, discovered a novel molecular system that uses an alternative chemical energy and employs a novel mechanism to perform mechanical work.
• By repeatedly contracting and expanding, this molecular motor functions similarly to a classical Stirling engine and helps to distribute cargo to membrane-bound organelles
• It is the first motor using two components, two differently sized proteins, Rab5 and EEA1, and is driven by GTP instead of ATP.
• In a 2016 paper, re­ searchers from Australia and Germany reported that when an enzyme called Rab5 binds to a long protein called EEA1, the protein loses its taut and rigid shape and becomes floppy. This ‘collapse’ pulls two membranes inside a cell closer to each other.
• In the new study, researchers have reported that EEA1 regains its rigid shape in another mechanism so that it can become floppy again to pull the membranes closer, creating a new kind of two-part molecular motor.
• When the 2016 paper was published, it was unclear whether EEA1 could resume its rigid shape, so that the whole process could repeat itself without the help of other proteins.
• The researchers of the latest study reported that EEA1 draws energy from a reaction called GTP hydrolysis to become rigid again. The GTP hydrolysis is mediated by enzymes called GTPases. Rab5 is one such.