Science Signaling Podcast: 2 September 2014

The kinase PK3 inhibits new protein production in Trypanosoma brucei in response to endoplasmic reticulum stress. This Podcast features an interview with Shulamit Michaeli, senior author of a Research Article that appears in the 2 September 2014 issue of Science Signaling, about a kinase that's important for a parasite to respond to stress. Trypanosoma brucei is the unicellular parasite that causes African sleeping sickness and, like other trypanosomes, transcribes multiple genes as a single polycistronic RNA that is processed to yield individual mature mRNAs. A common 5′ leader sequence that is spliced onto each of these mRNAs is required for their translation. Therefore, the parasite can switch off production of new proteins by inhibiting production of the 5′ leader or its splicing onto mRNAs. Hope et al. found that the kinase PK3 translocates from the endoplasmic reticulum (ER) to the nucleus when the parasite experiences prolonged ER stress. In the nucleus, PK3 inhibits expression of the leader sequence, thus inhibiting the production of mRNAs and synthesis of new proteins.