5i2y
Crystal Structure of TPP1 K170A
Structural highlights
FunctionACD_HUMAN Component of the shelterin complex (telosome) that is involved in the regulation of telomere length and protection. Shelterin associates with arrays of double-stranded TTAGGG repeats added by telomerase and protects chromosome ends; without its protective activity, telomeres are no longer hidden from the DNA damage surveillance and chromosome ends are inappropriately processed by DNA repair pathways. Promotes binding of POT1 to single-stranded telomeric DNA. Modulates the inhibitory effects of POT1 on telomere elongation. The ACD-POT1 heterodimer enhances telomere elongation by increasing telomerase processivity. Plays a role in shelterin complex assembly. May play a role in organogenesis.[1] [2] [3] [4] [5] Publication Abstract from PubMedTelomerase replicates chromosome ends to facilitate continued cell division. Mutations that compromise telomerase function result in stem cell failure diseases, such as dyskeratosis congenita (DC). One such mutation (K170Delta), residing in the telomerase-recruitment factor TPP1, provides an excellent opportunity to structurally, biochemically, and genetically dissect the mechanism of such diseases. We show through site-directed mutagenesis and X-ray crystallography that this TPP1 disease mutation deforms the conformation of two critical amino acids of the TEL [TPP1's glutamate (E) and leucine-rich (L)] patch, the surface of TPP1 that binds telomerase. Using CRISPR-Cas9 technology, we demonstrate that introduction of this mutation in a heterozygous manner is sufficient to shorten telomeres in human cells. Our findings rule out dominant-negative effects of the mutation. Instead, these findings implicate reduced TEL patch dosage in causing telomere shortening. Our studies provide mechanistic insight into telomerase-deficiency diseases and encourage the development of gene therapies to counter such diseases. Structural and functional consequences of a disease mutation in the telomere protein TPP1.,Bisht K, Smith EM, Tesmer VM, Nandakumar J Proc Natl Acad Sci U S A. 2016 Nov 15;113(46):13021-13026. Epub 2016 Nov 2. PMID:27807141[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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