کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5913682 | 1162697 | 2015 | 9 صفحه PDF | دانلود رایگان |
The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. To investigate the proteolytic core of the ClpXP1/P2 protease from the cyanobacterium Synechococcus elongatus we have used a non-denaturing mass spectrometry approach. We show that the proteolytic core is a double ring tetradecamer consisting of an equal number of ClpP1 and ClpP2 subunits with masses of 21.70 and 23.44Â kDa, respectively. Two stoichiometries are revealed for the heptameric rings: 4ClpP1Â +Â 3ClpP2 and 3ClpP1Â +Â 4ClpP2. When combined in the double ring the stoichiometries are (4ClpP1Â +Â 3ClpP2)Â +Â (3ClpP1Â +Â 4ClpP2) and 2Â ÃÂ (3ClpP1Â +Â 4ClpP2) with a low population of a 2Â ÃÂ (4ClpP1Â +Â 3ClpP2) tetradecamer. The assignment of the stoichiometries is confirmed by collision-induced dissociation of selected charge states of the intact heptamer and tetradecamer. Presence of the heterodimers, heterotetramers and heterohexamers, and absence of the mono-oligomers, in the mass spectra of the partially denatured protease indicates that the ring complex consists of a chain of ClpP1/ClpP2 heterodimers with the ring completed by an additional ClpP1 or ClpP2 subunit.
Journal: Journal of Structural Biology - Volume 192, Issue 3, December 2015, Pages 519-527