Spectrin's E2/E3 ubiquitin conjugating/ligating activity is diminished in sickle cells.
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.
Chang
Tsui-Ling
TL
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.
Kakhniashvili
David G
DG
Goodman
Steven R
SR
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*
D017487:Ankyrins; D008024:Ligands; D020033:Protein Isoforms; D025801:Ubiquitin; D013049:Spectrin; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases