PMID: 30127001

 

    Legend: Gene, Sites

Title : Two novel protein O-glucosyltransferases that modify sites distinct from POGLUT1 and affect Notch trafficking and signaling

Abstract :
  1. The Notch-signaling pathway is normally activated by Notch-ligand interactions
  2. A recent structural analysis suggested that a novel O-linked hexose modification on serine 435 of the mammalian NOTCH1 core ligand-binding domain lies at the interface with its ligands
  3. This serine occurs between conserved cysteines 3 and 4 of Epidermal Growth Factor-like (EGF) repeat 11 of NOTCH1 , a site distinct from those modified by protein O-glucosyltransferase 1 ( POGLUT1 ), suggesting that a different enzyme is responsible
  4. Here, we identify two novel protein O-glucosyltransferases, POGLUT2 and POGLUT3 (formerly KDELC1 and KDELC2 , respectively), which transfer O-glucose (O-Glc) from UDP-Glc to serine 435
  5. Mass spectrometric analysis of NOTCH1 produced in HEK293T cells lacking POGLUT2 , POGLUT3 , or both genes showed that either POGLUT2 or POGLUT3 can add this novel O-Glc modification
  6. EGF11 of NOTCH2 does not have a serine residue in the same location for this O-glucosylation, but EGF10 of NOTCH3 (homologous to EGF11 in NOTCH1 and -2) is also modified at the same position
  7. Comparison of the sites suggests a consensus sequence for modification
  8. In vitro assays with POGLUT2 and POGLUT3 showed that both enzymes modified only properly folded EGF repeats and displayed distinct acceptor specificities toward NOTCH1 EGF11 and NOTCH3 EGF10
  9. Mutation of the O-Glc modification site on EGF11 ( serine 435 ) in combination with sensitizing O-fucose mutations in EGF8 or EGF12 affected cell-surface presentation of NOTCH1 or reduced activation of NOTCH1 by Delta-like1, respectively
  10. This study identifies a previously undescribed mechanism for fine-tuning the Notch-signaling pathway in mammals
Output (sent_index, trigger, protein, sugar, site):
  • 2. domain, , -, a novel O-linked hexose modification, domain
  • 2. modification, , -, a novel O-linked hexose modification, domain
  • 2. modification, , -, serine 435, serine 435
  • 3. NOTCH1, , NOTCH1, Epidermal Growth Factor-like (EGF) repeat 11, -
  • 9. site, , -, serine 435, serine 435
Output(Part-Of) (sent_index, protein, site):
  • 2. NOTCH1, domain
*Output_Site_Fusion* (sent_index, protein, sugar, site):
  • 2. POGLUT1, serine 435, serine 435
  • 9. POGLUT1, serine 435, serine 435

 

 

Protein NCBI ID SENTENCE INDEX
KDELC1 79070 4
POGLUT1 56983 0,3
Notch 4851 0,1,10
KDELC2 143888 4