| Structural highlights
Disease
[SOS1_HUMAN] Defects in SOS1 are the cause of gingival fibromatosis 1 (GGF1) [MIM:135300]; also known as GINGF1. Gingival fibromatosis is a rare overgrowth condition characterized by a benign, slowly progressive, nonhemorrhagic, fibrous enlargement of maxillary and mandibular keratinized gingiva. GGF1 is usually transmitted as an autosomal dominant trait, although sporadic cases are common.[1] Defects in SOS1 are the cause of Noonan syndrome type 4 (NS4) [MIM:610733]. NS4 is an autosomal dominant disorder characterized by dysmorphic facial features, short stature, hypertelorism, cardiac anomalies, deafness, motor delay, and a bleeding diathesis. It is a genetically heterogeneous and relatively common syndrome, with an estimated incidence of 1 in 1000-2500 live births. Rarely, NS4 is associated with juvenile myelomonocytic leukemia (JMML). SOS1 mutations engender a high prevalence of pulmonary valve disease; atrial septal defects are less common.[2] [3] [4] [5] [6] [7] [8] [9]
Function
[SOS1_HUMAN] Promotes the exchange of Ras-bound GDP by GTP.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Membrane-bound Ras is activated by translocation of the Son of Sevenless (SOS) protein to the plasma membrane. SOS is inactive unless Ras is bound to an allosteric site on SOS, and the Dbl homology (DH) and Pleckstrin homology (PH) domains of SOS (the DH-PH unit) block allosteric Ras binding. We showed previously that the activity of SOS at the membrane increases with the density of PIP(2) and the local concentration of Ras-GTP, which synergize to release the DH-PH unit. Here we present a new crystal structure of SOS that contains the N-terminal histone domain in addition to the DH-PH unit and the catalytic unit (SOS(HDFC), residues 1-1049). The structure reveals that the histone domain plays a dual role in occluding the allosteric site and in stabilizing the autoinhibitory conformation of the DH-PH unit. Additional insight is provided by kinetic analysis of the activation of membrane-bound Ras by mutant forms of SOS that contain mutations in the histone and the PH domains (E108K, C441Y, and E433K) that are associated with Noonan syndrome, a disease caused by hyperactive Ras signaling. Our results indicate that the histone domain and the DH-PH unit are conformationally coupled, and that the simultaneous engagement of the membrane by a PH domain PIP(2)-binding interaction and electrostatic interactions between a conserved positively charged patch on the histone domain and the negatively charged membrane coincides with a productive reorientation of SOS at the membrane and increased accessibility of both Ras binding sites on SOS.
Role of the histone domain in the autoinhibition and activation of the Ras activator Son of Sevenless.,Gureasko J, Kuchment O, Makino DL, Sondermann H, Bar-Sagi D, Kuriyan J Proc Natl Acad Sci U S A. 2010 Feb 4. PMID:20133692[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hart TC, Zhang Y, Gorry MC, Hart PS, Cooper M, Marazita ML, Marks JM, Cortelli JR, Pallos D. A mutation in the SOS1 gene causes hereditary gingival fibromatosis type 1. Am J Hum Genet. 2002 Apr;70(4):943-54. Epub 2002 Feb 26. PMID:11868160 doi:S0002-9297(07)60301-2
- ↑ Roberts AE, Araki T, Swanson KD, Montgomery KT, Schiripo TA, Joshi VA, Li L, Yassin Y, Tamburino AM, Neel BG, Kucherlapati RS. Germline gain-of-function mutations in SOS1 cause Noonan syndrome. Nat Genet. 2007 Jan;39(1):70-4. Epub 2006 Dec 3. PMID:17143285 doi:ng1926
- ↑ Tartaglia M, Pennacchio LA, Zhao C, Yadav KK, Fodale V, Sarkozy A, Pandit B, Oishi K, Martinelli S, Schackwitz W, Ustaszewska A, Martin J, Bristow J, Carta C, Lepri F, Neri C, Vasta I, Gibson K, Curry CJ, Siguero JP, Digilio MC, Zampino G, Dallapiccola B, Bar-Sagi D, Gelb BD. Gain-of-function SOS1 mutations cause a distinctive form of Noonan syndrome. Nat Genet. 2007 Jan;39(1):75-9. Epub 2006 Dec 13. PMID:17143282 doi:10.1038/ng1939
- ↑ Ko JM, Kim JM, Kim GH, Yoo HW. PTPN11, SOS1, KRAS, and RAF1 gene analysis, and genotype-phenotype correlation in Korean patients with Noonan syndrome. J Hum Genet. 2008;53(11-12):999-1006. doi: 10.1007/s10038-008-0343-6. Epub 2008, Nov 20. PMID:19020799 doi:10.1007/s10038-008-0343-6
- ↑ Hanna N, Parfait B, Talaat IM, Vidaud M, Elsedfy HH. SOS1: a new player in the Noonan-like/multiple giant cell lesion syndrome. Clin Genet. 2009 Jun;75(6):568-71. doi: 10.1111/j.1399-0004.2009.01149.x. Epub, 2009 May 5. PMID:19438935 doi:10.1111/j.1399-0004.2009.01149.x
- ↑ Longoni M, Moncini S, Cisternino M, Morella IM, Ferraiuolo S, Russo S, Mannarino S, Brazzelli V, Coi P, Zippel R, Venturin M, Riva P. Noonan syndrome associated with both a new Jnk-activating familial SOS1 and a de novo RAF1 mutations. Am J Med Genet A. 2010 Sep;152A(9):2176-84. doi: 10.1002/ajmg.a.33564. PMID:20683980 doi:10.1002/ajmg.a.33564
- ↑ Fabretto A, Kutsche K, Harmsen MB, Demarini S, Gasparini P, Fertz MC, Zenker M. Two cases of Noonan syndrome with severe respiratory and gastroenteral involvement and the SOS1 mutation F623I. Eur J Med Genet. 2010 Sep-Oct;53(5):322-4. doi: 10.1016/j.ejmg.2010.07.011. Epub , 2010 Jul 29. PMID:20673819 doi:10.1016/j.ejmg.2010.07.011
- ↑ Denayer E, Devriendt K, de Ravel T, Van Buggenhout G, Smeets E, Francois I, Sznajer Y, Craen M, Leventopoulos G, Mutesa L, Vandecasseye W, Massa G, Kayserili H, Sciot R, Fryns JP, Legius E. Tumor spectrum in children with Noonan syndrome and SOS1 or RAF1 mutations. Genes Chromosomes Cancer. 2010 Mar;49(3):242-52. doi: 10.1002/gcc.20735. PMID:19953625 doi:10.1002/gcc.20735
- ↑ Lepri F, De Luca A, Stella L, Rossi C, Baldassarre G, Pantaleoni F, Cordeddu V, Williams BJ, Dentici ML, Caputo V, Venanzi S, Bonaguro M, Kavamura I, Faienza MF, Pilotta A, Stanzial F, Faravelli F, Gabrielli O, Marino B, Neri G, Silengo MC, Ferrero GB, Torrrente I, Selicorni A, Mazzanti L, Digilio MC, Zampino G, Dallapiccola B, Gelb BD, Tartaglia M. SOS1 mutations in Noonan syndrome: molecular spectrum, structural insights on pathogenic effects, and genotype-phenotype correlations. Hum Mutat. 2011 Jul;32(7):760-72. doi: 10.1002/humu.21492. Epub 2011 Apr 28. PMID:21387466 doi:10.1002/humu.21492
- ↑ Gureasko J, Kuchment O, Makino DL, Sondermann H, Bar-Sagi D, Kuriyan J. Role of the histone domain in the autoinhibition and activation of the Ras activator Son of Sevenless. Proc Natl Acad Sci U S A. 2010 Feb 4. PMID:20133692
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