ADP-ribosylation of an ∼70-kilodalton protein of Klebsiella pneumoniae

Abstract

An ∼70-kDa protein in the culture supernatant of a human pathogenic strain of Klebsiella pneumoniae was labeled in the presence of [32P-adenylate]NAD. Labeling was significantly increased by the addition of dithiothreitol (>1 mM) but prevented by treatment of the culture supernatant for 3 min at 56°C. The addition of unlabeled NAD, but not of ADP-ribose, blocked labeling of the ∼70-kDa protein. The radioactive label was released by formic acid but not by HgCl2 (1 mM) or neutral hydroxylamine (0.5 M). The addition of homogenates of human platelets, human neutrophils, rat brain, rat lung, or rat spleen tissues to the culture supernatant did not induce labeling of eukaryotic proteins. The data indicate that the K. pneumoniae strain produces ADP-ribosyltransferase which modifies an endogenous protein.