1vyx: Difference between revisions

[[Image:1vyx.gif|left|200px]]

'''SOLUTION STRUCTURE OF THE KSHV K3 N-TERMINAL DOMAIN'''

RING domains are found in a large number of eukaryotic proteins. Most function as E3 ubiquitin-protein ligases, catalyzing the terminal step in the ubiquitination process. Structurally, these domains have been characterized as binding two zinc ions in a stable cross-brace motif. The tumorigenic human gamma-herpesvirus Kaposi's sarcoma-associated herpesvirus encodes a ubiquitin-protein ligase termed K3, which functions as an immune evasion molecule by ubiquitinating major histocompatibility complex class I. K3 possesses at its N terminus a domain related to cellular RING domains but with an altered zinc ligand arrangement. This domain was initially characterized as a plant homeodomain, a structure not previously known to function as an E3. Here, it is conclusively demonstrated that the K3 N-terminal domain is a variant member of the RING domain family and not a plant homeodomain. The domain is found to interact with the cellular ubiquitin-conjugating enzymes UbcH5A to -C and UbcH13, which dock to the equivalent surface as on classical cellular RING domains. Interaction with UbcH13 suggests a possible role for K3 in catalyzing Lys(63)-linked ubiquitination.

1VYX is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Human_herpesvirus_8 Human herpesvirus 8]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VYX OCA].  

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