Ribonuclease L proteolysis in peripheral blood mononuclear cells of chronic fatigue syndrome patients.
A 37-kDa binding polypeptide accumulates in peripheral blood mononuclear cell (PBMC) extracts from chronic fatigue syndrome (CFS) patients and is being considered as a potential diagnostic marker (De Meirleir, K., Bisbal, C., Campine, I., De Becker, P., Salehzada, T., Demettre, E., and Lebleu, B. (2000) Am. J. Med. 108, 99-105). We establish here that this low molecular weight 2-5A-binding polypeptide is a truncated form of the native 2-5A-dependent ribonuclease L (RNase L), generated by an increased proteolytic activity in CFS PBMC extracts. RNase L proteolysis in CFS PBMC extracts can be mimicked in a model system in which recombinant RNase L is treated with human leukocyte elastase. RNase L proteolysis leads to the accumulation of two major fragments with molecular masses of 37 and 30 kDa. The 37-kDa fragment includes the 2-5A binding site and the N-terminal end of native RNase L. The 30-kDa fragment includes the catalytic site in the C-terminal part of RNase L. Interestingly, RNase L remains active and 2-5A-dependent when degraded into its 30- and 37-kDa fragments by proteases of CFS PBMC extract or by purified human leukocyte elastase. The 2-5A-dependent nuclease activity of the truncated RNase L could result from the association of these digestion products, as suggested in pull down experiments.
UMR 5124 CNRS, Université Montpellier 2, 34293 Montpellier, France.
Edith
E
Demettre
Lionel
L
Bastide
Anne
A
D'Haese
Karen
K
De Smet
Kenny
K
De Meirleir
Kiet P
KP
Tiev
Patrick
P
Englebienne
Bernard
B
Lebleu
D015088:2',5'-Oligoadenylate Synthetase / Q000378:metabolism; D015673:Fatigue Syndrome, Chronic / Q000097:blood / Q000201:enzymology*; D006801:Humans; D006868:Hydrolysis; D009000:Monocytes / Q000201:enzymology*; D011994:Recombinant Proteins / Q000097:blood; D012260:Ribonucleases / Q000097:blood*
D011994:Recombinant Proteins; D015088:2',5'-Oligoadenylate Synthetase; D012260:Ribonucleases