| Structural highlights
Function
[ISG15_HUMAN] Ubiquitin-like protein that is conjugated to intracellular target proteins after IFN-alpha or IFN-beta stimulation. Its enzymatic pathway is partially distinct from that of ubiquitin, differing in substrate specificity and interaction with ligating enzymes. ISG15 conjugation pathway uses a dedicated E1 enzyme, but seems to converge with the Ub conjugation pathway at the level of a specific E2 enzyme. Targets include STAT1, SERPINA3G/SPI2A, JAK1, MAPK3/ERK1, PLCG1, EIF2AK2/PKR, MX1/MxA, and RIG-1. Deconjugated by USP18/UBP43. Shows specific chemotactic activity towards neutrophils and activates them to induce release of eosinophil chemotactic factors. May serve as a trans-acting binding factor directing the association of ligated target proteins to intermediate filaments. May also be involved in autocrine, paracrine and endocrine mechanisms, as in cell-to-cell signaling, possibly partly by inducing IFN-gamma secretion by monocytes and macrophages. Seems to display antiviral activity during viral infections.[1] [2] [3] [4] [5] [6] In response to IFN-tau secreted by the conceptus, may ligate to and regulate proteins involved in the release of prostaglandin F2-alpha (PGF), and thus prevent lysis of the corpus luteum and maintain the pregnancy (By similarity).[7] [8] [9] [10] [11] [12]
Publication Abstract from PubMed
The attachment of ubiquitin (Ub) and the Ub-like (Ubl) molecule interferon-stimulated gene 15 (ISG15) to cellular proteins mediates important innate antiviral responses. Ovarian tumor (OTU) domain proteases from nairoviruses and arteriviruses were recently found to remove these molecules from host proteins, which inhibits Ub and ISG15-dependent antiviral pathways. This contrasts with the Ub-specific activity of known eukaryotic OTU-domain proteases. Here we describe crystal structures of a viral OTU domain from the highly pathogenic Crimean-Congo haemorrhagic fever virus (CCHFV) bound to Ub and to ISG15 at 2.5-A and 2.3-A resolution, respectively. The complexes provide a unique structural example of ISG15 bound to another protein and reveal the molecular mechanism of an ISG15 cross-reactive deubiquitinase. To accommodate structural differences between Ub and ISG15, the viral protease binds the beta-grasp folds of Ub and C-terminal Ub-like domain of ISG15 in an orientation that is rotated nearly 75 degrees with respect to that observed for Ub bound to a representative eukaryotic OTU domain from yeast. Distinct structural determinants necessary for binding either substrate were identified and allowed the reengineering of the viral OTU protease into enzymes with increased substrate specificity, either for Ub or for ISG15. Our findings now provide the basis to determine in vivo the relative contributions of deubiquitination and deISGylation to viral immune evasion tactics, and a structural template of a promiscuous deubiquitinase from a haemorrhagic fever virus that can be targeted for inhibition using small-molecule-based strategies.
Structural basis for the removal of ubiquitin and interferon-stimulated gene 15 by a viral ovarian tumor domain-containing protease.,James TW, Frias-Staheli N, Bacik JP, Levingston Macleod JM, Khajehpour M, Garcia-Sastre A, Mark BL Proc Natl Acad Sci U S A. 2011 Jan 18. PMID:21245344[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Loeb KR, Haas AL. The interferon-inducible 15-kDa ubiquitin homolog conjugates to intracellular proteins. J Biol Chem. 1992 Apr 15;267(11):7806-13. PMID:1373138
- ↑ Loeb KR, Haas AL. Conjugates of ubiquitin cross-reactive protein distribute in a cytoskeletal pattern. Mol Cell Biol. 1994 Dec;14(12):8408-19. PMID:7526157
- ↑ Narasimhan J, Potter JL, Haas AL. Conjugation of the 15-kDa interferon-induced ubiquitin homolog is distinct from that of ubiquitin. J Biol Chem. 1996 Jan 5;271(1):324-30. PMID:8550581
- ↑ Knight E Jr, Cordova B. IFN-induced 15-kDa protein is released from human lymphocytes and monocytes. J Immunol. 1991 Apr 1;146(7):2280-4. PMID:2005397
- ↑ Lenschow DJ, Giannakopoulos NV, Gunn LJ, Johnston C, O'Guin AK, Schmidt RE, Levine B, Virgin HW 4th. Identification of interferon-stimulated gene 15 as an antiviral molecule during Sindbis virus infection in vivo. J Virol. 2005 Nov;79(22):13974-83. PMID:16254333 doi:79/22/13974
- ↑ Zhao C, Denison C, Huibregtse JM, Gygi S, Krug RM. Human ISG15 conjugation targets both IFN-induced and constitutively expressed proteins functioning in diverse cellular pathways. Proc Natl Acad Sci U S A. 2005 Jul 19;102(29):10200-5. Epub 2005 Jul 11. PMID:16009940 doi:0504754102
- ↑ Loeb KR, Haas AL. The interferon-inducible 15-kDa ubiquitin homolog conjugates to intracellular proteins. J Biol Chem. 1992 Apr 15;267(11):7806-13. PMID:1373138
- ↑ Loeb KR, Haas AL. Conjugates of ubiquitin cross-reactive protein distribute in a cytoskeletal pattern. Mol Cell Biol. 1994 Dec;14(12):8408-19. PMID:7526157
- ↑ Narasimhan J, Potter JL, Haas AL. Conjugation of the 15-kDa interferon-induced ubiquitin homolog is distinct from that of ubiquitin. J Biol Chem. 1996 Jan 5;271(1):324-30. PMID:8550581
- ↑ Knight E Jr, Cordova B. IFN-induced 15-kDa protein is released from human lymphocytes and monocytes. J Immunol. 1991 Apr 1;146(7):2280-4. PMID:2005397
- ↑ Lenschow DJ, Giannakopoulos NV, Gunn LJ, Johnston C, O'Guin AK, Schmidt RE, Levine B, Virgin HW 4th. Identification of interferon-stimulated gene 15 as an antiviral molecule during Sindbis virus infection in vivo. J Virol. 2005 Nov;79(22):13974-83. PMID:16254333 doi:79/22/13974
- ↑ Zhao C, Denison C, Huibregtse JM, Gygi S, Krug RM. Human ISG15 conjugation targets both IFN-induced and constitutively expressed proteins functioning in diverse cellular pathways. Proc Natl Acad Sci U S A. 2005 Jul 19;102(29):10200-5. Epub 2005 Jul 11. PMID:16009940 doi:0504754102
- ↑ James TW, Frias-Staheli N, Bacik JP, Levingston Macleod JM, Khajehpour M, Garcia-Sastre A, Mark BL. Structural basis for the removal of ubiquitin and interferon-stimulated gene 15 by a viral ovarian tumor domain-containing protease. Proc Natl Acad Sci U S A. 2011 Jan 18. PMID:21245344 doi:10.1073/pnas.1013388108
|
