Stimulation of ADP-ribosyl cyclase activity of the cell surface antigen CD38 by zinc ions resulting from inhibition of its NAD+ glycohydrolase activity.
The lymphocyte cell surface antigen, CD38, which has an amino acid sequence similar to Aplysia ADP-ribosyl cyclase, catalyzes not only the hydrolysis of NAD+ and 1-(5-phospho-beta-D-ribosyl) adenosine 5'-phosphate cyclic anhydride (cyclic ADP-ribose) but also the formation of cyclic ADP-ribose from NAD+. To characterize the bifunctional enzyme properties, we produced the recombinant CD38 fused with a maltose-binding protein (MBP-CD38). Zinc ions stimulated the ADP-ribosyl cyclase activity of MBP-CD38, but inversely inhibited its NAD+ glycohydrolase activity which was approximately 100-fold dominant to the cyclase activity in the absence of Zn2+. Such dual effects of Zn2+ were also observed in the native membrane-bound CD38 of HL-60 cells which had been caused to differentiate by retinoic acid. Zinc ions inhibited the NAD+ glycohydrolase reaction catalyzed by MBP-CD38 in an uncompetitive manner, whereas they enhanced the ADP-ribosyl cyclase reaction without affecting the Km value for NAD+. There was an increase in the fluorescence intensity of a hydrophobic fluorescent probe, 8-anilino-1-naphthalenesulfonate, in the presence of MBP-CD38. The fluorescence increase was further enhanced by the addition of Zn2+ with a shift in the maximum emission wavelength from 484 nm to 470 nm, suggesting that Zn2+ caused conformational changes of MBP-CD38. These results indicate that Zn2+ directly interacts with CD38 to stimulate its ADP-ribosyl cyclase with inhibition of its NAD+ glycohydrolase, probably due to prevention of the access of water molecule to an intermediate of the enzymesubstrate complex.
Kukimoto
I
I
Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Hoshino
S
S
Kontani
K
K
Inageda
K
K
Nishina
H
H
Takahashi
K
K
Katada
T
T
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000817:Anilino Naphthalenesulfonates; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism*; D000943:Antigens, Differentiation / Q000737:chemistry / Q000378:metabolism*; D004789:Enzyme Activation; D005456:Fluorescent Dyes; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins; D009699:N-Glycosyl Hydrolases / Q000737:chemistry / Q000378:metabolism*; D009244:NAD+ Nucleosidase / Q000037:antagonists & inhibitors*; D015032:Zinc / Q000494:pharmacology*
D000817:Anilino Naphthalenesulfonates; D015703:Antigens, CD; D000943:Antigens, Differentiation; D005456:Fluorescent Dyes; D008562:Membrane Glycoproteins; C027132:1-anilino-8-naphthalenesulfonate; D009699:N-Glycosyl Hydrolases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1; D015032:Zinc