Water is good for a lot of things, from quenching your thirst to reducing the BO levels of your scuzzy roommate. But recent work from the University of Michigan, to be published next week in PNAS, shows that water is also an essential part of a type of cell enzyme called a ribozyme. Ribozymes accelerate chemical reactions inside cells, and are able to change their physical conformation between an ‘active’ and ‘inactive’ state.
Previous work in the lab of Dr. Nils Walter has shown that changes which occur anywhere on the ribozyme, even far away from the site of the reaction, change the rate at which the reaction occurs. This suggested that information about changes in distant parts of the ribozyme travels through a network to ribozyme’s core, where chemical reactions take place. The recent paper shows that water molecules trapped inside the ribozyme’s core are essential components of that network.
The network acts like a jostling crowd at a cocktail party, where hydrogen bonds—weak, electrostatic attractions between molecules or parts of molecules—take the place of handshakes. Water molecules trapped in ribozymes can form hydrogen bonds with other water molecules or with parts of the ribozyme molecule.
“The way we interpret the data is that in ribozymes, a chemical modification introduced at one place changes the local structure slightly,” Walter said. The building blocks making up the ribozyme wiggle into different positions and in the process must let go of some hydrogen bonds and form others, just as partygoers shift position and engage with other guests.
“As a consequence, their hydrogen bonding partners—some of which are water molecules—also rearrange. Then their hydrogen bonding partners also rearrange, creating a domino effect, where a local modification spreads throughout the molecule and modifies the structure elsewhere, even at quite a distance,” Walter said.
Hat tip Bob Abu!