LA JOLLA, CA-- It takes dozens of chemical reactions for a cell to make isoprenoids, a diverse class of molecules found in every type of living organism. Cholesterol, for example, an important component of the membranes of cells, is a large isoprenoid chemical. The molecule that gives oranges their citrusy smell and taste is an isoprenoid, as is the natural antimalarial drug artemisinin.
Now, researchers at the Salk Institute have discovered a missing step in the chain of reactions that some cells use to produce isoprenoids. Their findings, published December 10 in eLife, are not only an advance in basic science, but have immediate implications for how isoprenoids are produced for commercial use, says Joseph Noel, professor and director of Salk's Jack H. Skirball Center for Chemical Biology and Proteomics and a Howard Hughes Medical Institute Investigator.
"It turns out that not all organisms make these very important products in the way that we thought they did," says Noel, holder of Salk's Arthur and Julie Woodrow Chair and the senior author of the new paper.
All larger isoprenoids are derived from a common building block molecule called isopentenyl diphosphate (IPP), which can be made through two chemical pathways. Animal cells use the mevalonate pathway to make IPP, many bacterial cells use a pathway dubbed DXP, and plant cells use both. But scientists have struggled to understand how archaebacteria, and some bacteria, produce IPP. While many of these organisms lack proteins that are key to the DXP pathway, they're also missing the proteins that perform two final steps of the mevalonate pathway. Normally, these production steps involve first adding phosphate to the intermediate molecule, and then removing an atom of carbon.
In 2006, a team of scientists discovered that some bacteria had an enzyme called isopentenyl phosphate kinase (IPK), which could add phosphate to the precursor molecule only if the carbon ha
|Contact: Kat Kearney|