Abstract
Glutamine synthetase from Escherichia coli was inactivated by chemical modification with arginine-specific reagents (Colanduoni, J. A., and Villafranca, J. J. (1985) Biochem. Biophys. Res. Commun. 126, 412-418). E. coli glutamine synthetase was also a substrate for an erythrocyte NAD:arginine ADP-ribosyltransferase. Transfer of one ADP-ribosyl group/subunit of glutamine synthetase caused loss of both biosynthetic and gamma-glutamyltransferase activity. The ADP-ribose moiety was enzymatically removed by an erythrocyte ADP-ribosylarginine hydrolase, resulting in return of function. The site of ADP-ribosylation was arginine 172, determined by isolation of the ADP-ribosylated tryptic peptide. Arginine 172 lies in a central loop that extends into the core formed by the 12 subunits of the native enzyme. The central loop is important in anchoring subunits together to yield the spatial orientation required for catalytic activity. ADP-ribosylation may thus inactivate glutamine synthetase by disrupting the normal subunit alignment. Enzyme-catalyzed ADP-ribosylation may provide a simple, specific technique to probe the role of arginine residues in the structure and function of proteins.
Highlights
From the $Luboratory of Cellular Metabolism and the
Glutamine synthetase was incubated with the ADP-ribosyltransferase as described under “Experimental Procedures.” 0, y-glutamyltransferase activity; n, glutamine biosynthetic activity
Glutamine synthetase was incubated with the ADP-ribosyltransferase as described under and spectra were obtained by the in-line diode array detector
Summary
From the $Luboratory of Cellular Metabolism and the Transfer of one ADP-ribosyl group/subunit of glutamine synthetase caused loss of both biosynthetic and y-glutamyltransferase activity. The ADP-ribose moiety was enzymatically removed by an erythrocyte. Arginine 172 lies in a central loop that extends into the core formed by the 12 subunits of the native enzyme. ADP-ribosylation may inactivate glutamine synthetase by disrupting the normal subunit alignment. ADP-ribosylation may provide a simple, specific technique to probe the role of arginine residues in the structure and function of proteins. ADP-ribosylation, a covalent modification in which the ADP-ribose moiety of NAD is transferred to protein, has been identified in phage, bacteria, and eucaryotic cells [1, 2]. Choleragen (cholera toxin) and Escherichia coli heat-labile enterotoxin, agents involved in the pathogenesis of cholera and travelers’ diarrhea, respectively, exert their effects on target cells by ADP-
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
