| First Author | Gavriljuk K | Year | 2012 |
| Journal | Proc Natl Acad Sci U S A | Volume | 109 |
| Issue | 52 | Pages | 21348-53 |
| PubMed ID | 23236136 | Mgi Jnum | J:193181 |
| Mgi Id | MGI:5467872 | Doi | 10.1073/pnas.1214431110 |
| Citation | Gavriljuk K, et al. (2012) Catalytic mechanism of a mammalian Rab.RabGAP complex in atomic detail. Proc Natl Acad Sci U S A 109(52):21348-53 |
| abstractText | Rab GTPases, key regulators of vesicular transport, hydrolyze GTP very slowly unless assisted by Rab GTPase-activating proteins (RabGAPs). Dysfunction of RabGAPs is involved in many diseases. By combining X-ray structure analysis and time-resolved FTIR spectroscopy we reveal here the detailed molecular reaction mechanism of a complex between human Rab and RabGAP at the highest possible spatiotemporal resolution and in atomic detail. A glutamine residue of Rab proteins (cis-glutamine) that is essential for intrinsic activity is less important in the GAP-activated reaction. During generation of the RabGAP.Rab:GTP complex, there is a rapid conformational change in which the cis-glutamine is replaced by a glutamine from RabGAP (trans-glutamine); this differs from the RasGAP mechanism, where the cis-glutamine is also important for GAP catalysis. However, as in the case of Ras, a trans-arginine is also recruited to complete the active center during this conformational change. In contrast to the RasGAP mechanism, an accumulation of a state in which phosphate is bound is not observed, and bond breakage is the rate-limiting step. The movement of trans-glutamine and trans-arginine into the catalytic site and bond breakage during hydrolysis are monitored in real time. The combination of X-ray structure analysis and time-resolved FTIR spectroscopy provides detailed insight in the catalysis of human Rab GTPases. |
