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- Aside from the catalytic site interactions there are two main interactions between ubiquitin and UBA11, a hydrophobic interface, and the polar interface between ubiquitin and first-catalytic cysteine half domain, FCCH, which contains the E1 active site cysteine. The hydrophobic interaction is maximized by interactions between the Phe898, Leu903, and Phe905 on UBA1 and the Leu8, Ile44 and Val70 residues on ubiquitin1. Additionally this interaction is further supported by a hydrogen bond between the Asn900 residue on UBA1 and the carbonyl oxygen of ubiquitin’s Leu81. The interaction between ubiquitin’s c-terminus and the FCCH domain of UBA1 relies on a deep groove formed from residues 175-265 in UBA11. Four polar residues on ubiquitin, Lys11, Thr12, Gln31, and Asp32, form hydrogen bonds with three polar residues, Arg202, Gly204, and Glu206, of UBA1.1 [1]
E2 interactions
When Ubiquitin binds, Uba1 then coordinates the transfer of Ubiquitin onto an E2 enzyme. The E2 enzyme (seen in pink) with Uba1 in the cavity where a transthioesterfication of Ubiquitin from the catalytic cysteine of Uba1 to the catalytic cysteine of the E2 occurs. The E2, in conjunction with the E3 enzyme, transfers the Ubiquitin onto its final substrate.[1] [5]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Lee I, Schindelin H. Structural Insights into E1-Catalyzed Ubiquitin Activation and Transfer to Conjugating Enzymes. Cell 134, 268–278 (2008).
- ↑ 2.0 2.1 2.2 Groettrup, M.; Pelzer, C.; Schmidtke, G.; Hofmann, K. Activating the ubiquitin family: UBA6 challenges the field. Trends Biochem. Sci. 2008, 33, 230-237. DOI:http://dx.doi.org/10.1016/j.tibs.2008.01.005
- ↑ 3.0 3.1 Chen, Z. J.; Sun, L. J. Nonproteolytic Functions of Ubiquitin in Cell Signaling. Mol. Cell 2009, 33, 275-286. DOI:http://dx.doi.org/10.1016/j.molcel.2009.01.014.
- ↑ 4.0 4.1 4.2 McGrath, J. P.; Jentsch, S.; Varshavsky, A. UBA 1: an essential yeast gene encoding ubiquitin-activating enzyme. EMBO J. 1991, 10, 227-236.
- ↑ Walden H, Podgorski MS, Huang DT, Miller DW, Howard RJ, Minor DL Jr, Holton JM, Schulman BA. The structure of the APPBP1-UBA3-NEDD8-ATP complex reveals the basis for selective ubiquitin-like protein activation by an E1. Molecular Cell 12, 1427–1437 (2003).
