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| ==Overview==
| | {{ABSTRACT_11591345}} |
| BACKGROUND: Ubiquitin-conjugating enzymes (E2s) are central enzymes involved in ubiquitin-mediated protein degradation. During this process, ubiquitin (Ub) and the E2 protein form an unstable E2-Ub thiolester intermediate prior to the transfer of ubiquitin to an E3-ligase protein and the labeling of a substrate for degradation. A series of complex interactions occur among the target substrate, ubiquitin, E2, and E3 in order to efficiently facilitate the transfer of the ubiquitin molecule. However, due to the inherent instability of the E2-Ub thiolester, the structural details of this complex intermediate are not known. RESULTS: A three-dimensional model of the E2-Ub thiolester intermediate has been determined for the catalytic domain of the E2 protein Ubc1 (Ubc1(Delta450)) and ubiquitin from S. cerevisiae. The interface of the E2-Ub intermediate was determined by kinetically monitoring thiolester formation by 1H-(15)N HSQC spectra by using combinations of 15N-labeled and unlabeled Ubc1(Delta450) and Ub proteins. By using the surface interface as a guide and the X-ray structures of Ub and the 1.9 A structure of Ubc1(Delta450) determined here, docking simulations followed by energy minimization were used to produce the first model of a E2-Ub thiolester intermediate. CONCLUSIONS: Complementary surfaces were found on the E2 and Ub proteins whereby the C terminus of Ub wraps around the E2 protein terminating in the thiolester between C88 (Ubc1(Delta450)) and G76 (Ub). The model supports in vivo and in vitro experiments of E2 derivatives carrying surface residue substitutions. Furthermore, the model provides insights into the arrangement of Ub, E2, and E3 within a ternary targeting complex.
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| ==About this Structure== | | ==About this Structure== |
| 1FXT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. The following page contains interesting information on the relation of 1FXT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb60_1.html Ubiquitin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FXT OCA]. | | 1FXT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. The following page contains interesting information on the relation of 1FXT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb60_1.html Ubiquitin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FXT OCA]. |
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| ==Reference==
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| Structure of a conjugating enzyme-ubiquitin thiolester intermediate reveals a novel role for the ubiquitin tail., Hamilton KS, Ellison MJ, Barber KR, Williams RS, Huzil JT, McKenna S, Ptak C, Glover M, Shaw GS, Structure. 2001 Oct;9(10):897-904. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/11591345 11591345]
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| [[Category: Homo sapiens]] | | [[Category: Homo sapiens]] |
| [[Category: Protein complex]] | | [[Category: Protein complex]] |
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| [[Category: Williams, R S.]] | | [[Category: Williams, R S.]] |
| [[Category: Model of the interaction between yeast ubc1 and ubiquitin after the formation of a covalent thiolester]] | | [[Category: Model of the interaction between yeast ubc1 and ubiquitin after the formation of a covalent thiolester]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 16:53:08 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun 26 17:24:01 2008'' |