Serine protease inhibitors block N-terminal arginylation of proteins by inhibiting the arginylation of tRNA in rat brains

Abstract

The tRNA mediated, posttranslational, N-terminal arginylation of proteins occurs in all eukaryotic cells. In nervous tissue, these reactions can be inhibited by endogenous molecules with a molecular weight of between one thousand and five thousand. In the present experiments, exogenous serine protease inhibitors (10(-5) M or less) but not other types of protease inhibitors, were found to be able to block the arginylation of protein in extracts of rat brain homogenates. Inhibition was not by the usual mode of action of protease inhibitors, but by interfering (non-competitively) with the charging of tRNA. Since arginylated proteins are rapidly ubiquitinated and degraded by cytosolic proteases, serine protease inhibitors may act to stabilize proteins by a dual mechanism of inhibiting arginylation as well as inhibiting serine proteases.

Ubiquitin and the Enigma of Intracellular Protein Degradation

“…A prerequisite is that the N-terminus is not buried in the protein [191]. It has been reported that arginyl-tRNA-protein transferase can be inhibited by serine protease inhibitors [192]. Arginyl-tRNA-protein transferase, which is present in all cells, is typically assayed with BSA (K, -= 25 pM) [191].…”

Small molecule inhibitors of arginyltransferase regulate arginylation-dependent protein degradation, cell motility, and angiogenesis

“…Heparin, a widely used anticoagulant, inhibits ATE1 reaction in vitro [11], possibly through its action on Arg-tRNA synthetase (RRS) which produces Arg-charged tRNA used for arginyl transfer [12]. Similarly protease inhibitors indirectly inhibit protein arginylation in brain extracts by interfering with the charging of tRNA [13]. Finally, hemin, the Fe 3+ form of heme, was shown to inhibit ATE1 and promote its degradation in cells through ubiquitin-dependent proteolysis – an indirect effect, likely linked to hemin's action on proteasome, and possibly on RRS [14].…”

The effect of hypothalamic peptides, neurohormone C and proline-rich peptide-1on the Ca2+-handling system in heartin pathophysiological conditions

“…MDF released during pancreatic necrosis and/or during decompression in crush syndrome cannot cross the blood-brain barrier, but penetrates the brain after N-terminal arginylation [35]. This "re-uptake"mechanism works also for other small peptides formed in crush syndrome, which, crossing the BBB in the form of "arginine proteins" cause neurodegenerative lesions in the nervous tissue [35,46]. N-terminal arginylation of proteins occurs in all eukaryotic cells, and arginylated proteins are rapidly ubiquitinated and degraded by serine proteases, which can be inhibited by endogenous molecules with a molecular weight from one to five thousand [47].…”