Editors' ChoicePlant biology

Chloroplast Rescued by Ubiquitin

Science Signaling  06 Nov 2012:
Vol. 5, Issue 249, pp. ec285
DOI: 10.1126/scisignal.2003747

The ubiquitin proteasome system is important in the regulation of many nucleocytosolic processes. However, its regulatory reach was not thought to extend to the chloroplast. Using a forward-genetic screen in Arabidopsis, Ling et al. (see the Perspective by Kessler) identified a ubiquitin E3 ligase, termed SP1, embedded in the chloroplast outer envelope membrane. SP1 was found to target components of the chloroplast protein import machinery for degradation by the ubiquitin proteasome and was important for changes in chloroplast biogenesis.

Q. Ling, W. Huang, A. Baldwin, P. Jarvis, Chloroplast biogenesis is regulated by direct action of the ubiquitin-proteasome system. Science 338, 655–659 (2012). [Abstract] [Full Text]

F. Kessler, Chloroplast delivery by UPS. Science 338, 622–623 (2012). [Abstract] [Full Text]