title: Spectrin's E2/E3 ubiquitin conjugating/ligating activity is diminished in sickle cells.
abstract: Erythrocyte spectrin contains E2/E3 ubiquitin conjugating/ligating activity in its alpha subunit. Ankyrin is a target of spectrin's E2/E3 ubiquitin conjugating/ligating activity in vitro and in vivo. We compare the ubiquitination levels of ankyrin mediated by control and sickle cell spectrin using a biotinylated ubiquitin cell-free assay. Sickle cell spectrin has diminished ability to transfer ubiquitin from an intermediate spectrin-ubiquitin thioester adduct (alpha' spectrin) to ankyrin, which may be due to glutathiolation of spectrin's E2 and/or E3 active site cysteines. There is also a diminished ability of the sickle cell ankyrin to serve as target of spectrin's E2/E3 activity, probably due to oxidative damage to ankyrin. A direct correlation exists between the alpha'/alpha spectrin ratio and spectrin's ability to ubiquitinate ankyrin. There is also an inverse correlation between severity of the disease and the alpha'/alpha spectrin ratio in SS erythrocytes. These results suggest that reduced spectrin E2/E3 activity is an important determinant of sickle cell severity.
authors.affiliation: Department of Molecular and Cell Biology, UTD Sickle Cell Disease Research Center, Institute of Biomedical Sciences and Technology, The University of Texas at Dallas, Richardson, Texas, USA.
authors.forename: Tsui-Ling
authors.initials: TL
authors.lastname: Chang
authors.forename: David G
authors.initials: DG
authors.lastname: Kakhniashvili
authors.forename: Steven R
authors.initials: SR
authors.lastname: Goodman
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood* / Q000503:physiopathology; D017487:Ankyrins / Q000097:blood / Q000378:metabolism; D001773:Blood Cells / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008024:Ligands; D020033:Protein Isoforms / Q000097:blood; D012720:Severity of Illness Index; D013049:Spectrin / Q000737:chemistry / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000097:blood* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000097:blood*
chemical_list: D017487:Ankyrins; D008024:Ligands; D020033:Protein Isoforms; D025801:Ubiquitin; D013049:Spectrin; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases