| Structural highlights
Disease
[USB1_HUMAN] Dyskeratosis congenita;Poikiloderma with neutropenia. Poikiloderma with neutropenia (PN) [MIM:604173]: A genodermatosis characterized by poikiloderma, pachyonychia and chronic neutropenia. The disorder starts as a papular erythematous rash on the limbs during the first year of life. It gradually spreads centripetally and, as the papular rash resolves, hypo- and hyperpigmentation result, with development of telangiectasias. Another skin manifestation is pachyonychia, but alopecia and leukoplakia are distinctively absent. Patients have recurrent pneumonias that usually result in reactive airway disease and/or chronic cough. One of the most important extracutaneous symptoms is an increased susceptibility to infections, mainly affecting the respiratory system, primarily due to a chronic neutropenia and to neutrophil functional defects. Bone marrow abnormalities account for neutropenia and may evolve into myelodysplasia associated with the risk of leukemic transformation. Poikiloderma with neutropenia shows phenotypic overlap with Rothmund-Thomson syndrome. Note=The disease is caused by mutations affecting the gene represented in this entry.[1] [2]
Function
[USB1_HUMAN] Phosphodiesterase responsible for the U6 snRNA 3' end processing. Acts as an exoribonuclease (RNase) responsible for trimming the poly(U) tract of the last nucleotides in the pre-U6 snRNA molecule, leading to the formation of mature U6 snRNA 3' end-terminated with a 2',3'-cyclic phosphate.[3] [4]
Publication Abstract from PubMed
U6 small nuclear ribonucleoprotein (snRNP) biogenesis is essential for spliceosome assembly, but not well understood. Here, we report structures of the U6 RNA processing enzyme Usb1 from yeast and a substrate analog bound complex from humans. Unlike the human ortholog, we show that yeast Usb1 has cyclic phosphodiesterase activity that leaves a terminal 3' phosphate which prevents overprocessing. Usb1 processing of U6 RNA dramatically alters its affinity for cognate RNA-binding proteins. We reconstitute the post-transcriptional assembly of yeast U6 snRNP in vitro, which occurs through a complex series of handoffs involving 10 proteins (Lhp1, Prp24, Usb1 and Lsm2-8) and anti-cooperative interactions between Prp24 and Lhp1. We propose a model for U6 snRNP assembly that explains how evolutionarily divergent and seemingly antagonistic proteins cooperate to protect and chaperone the nascent snRNA during its journey to the spliceosome.The mechanism of U6 small nuclear ribonucleoprotein (snRNP) biogenesis is not well understood. Here the authors characterize the enzymatic activities and structures of yeast and human U6 RNA processing enzyme Usb1, reconstitute post-transcriptional assembly of yeast U6 snRNP in vitro, and propose a model for U6 snRNP assembly.
Usb1 controls U6 snRNP assembly through evolutionarily divergent cyclic phosphodiesterase activities.,Didychuk AL, Montemayor EJ, Carrocci TJ, DeLaitsch AT, Lucarelli SE, Westler WM, Brow DA, Hoskins AA, Butcher SE Nat Commun. 2017 Sep 8;8(1):497. doi: 10.1038/s41467-017-00484-w. PMID:28887445[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Volpi L, Roversi G, Colombo EA, Leijsten N, Concolino D, Calabria A, Mencarelli MA, Fimiani M, Macciardi F, Pfundt R, Schoenmakers EF, Larizza L. Targeted next-generation sequencing appoints c16orf57 as clericuzio-type poikiloderma with neutropenia gene. Am J Hum Genet. 2010 Jan;86(1):72-6. doi: 10.1016/j.ajhg.2009.11.014. Epub 2009, Dec 10. PMID:20004881 doi:10.1016/j.ajhg.2009.11.014
- ↑ Tanaka A, Morice-Picard F, Lacombe D, Nagy N, Hide M, Taieb A, McGrath J. Identification of a homozygous deletion mutation in C16orf57 in a family with Clericuzio-type poikiloderma with neutropenia. Am J Med Genet A. 2010 Jun;152A(6):1347-8. doi: 10.1002/ajmg.a.33455. PMID:20503306 doi:10.1002/ajmg.a.33455
- ↑ Mroczek S, Krwawicz J, Kutner J, Lazniewski M, Kucinski I, Ginalski K, Dziembowski A. C16orf57, a gene mutated in poikiloderma with neutropenia, encodes a putative phosphodiesterase responsible for the U6 snRNA 3' end modification. Genes Dev. 2012 Sep 1;26(17):1911-25. doi: 10.1101/gad.193169.112. Epub 2012 Aug , 16. PMID:22899009 doi:10.1101/gad.193169.112
- ↑ Hilcenko C, Simpson PJ, Finch AJ, Bowler FR, Churcher MJ, Jin L, Packman LC, Shlien A, Campbell P, Kirwan M, Dokal I, Warren AJ. Aberrant 3' oligoadenylation of spliceosomal U6 small nuclear RNA in poikiloderma with neutropenia. Blood. 2012 Nov 27. PMID:23190533 doi:10.1182/blood-2012-10-461491
- ↑ Didychuk AL, Montemayor EJ, Carrocci TJ, DeLaitsch AT, Lucarelli SE, Westler WM, Brow DA, Hoskins AA, Butcher SE. Usb1 controls U6 snRNP assembly through evolutionarily divergent cyclic phosphodiesterase activities. Nat Commun. 2017 Sep 8;8(1):497. doi: 10.1038/s41467-017-00484-w. PMID:28887445 doi:http://dx.doi.org/10.1038/s41467-017-00484-w
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