Reversible inhibition of protein splicing by zinc ion.
Protein splicing involves the self-catalyzed excision of a protein-splicing element, the intein, from flanking polypeptides, the exteins, which are concomitantly joined by a peptide bond. Taking advantage of recently developed in vitro systems in which protein splicing occurs in trans to assay for protein-splicing inhibitors, we discovered that low concentrations of Zn(2+) inhibited splicing mediated both by the RecA intein from Mycobacterium tuberculosis and by the naturally split DnaE intein from Synechocystis sp. PCC6803. Inhibition by Zn(2+) was also observed with a cis-splicing system involving the RecA intein. In all experimental systems used, inhibition by Zn(2+) could be completely reversed by the addition of EDTA. Zinc ion also inhibited hydroxylamine-dependent N-terminal cleavage of the RecA intein. All other divalent transition metal ions tested were less effective as inhibitors than Zn(2+). The reversible inhibition by Zn(2+) should be useful in studies of the mechanism of protein splicing and allow structural studies of unmodified protein-splicing precursors.
Mills
K V
KV
Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
Paulus
H
H
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D000458:Cyanobacteria; D009169:Mycobacterium tuberculosis; D019154:Protein Splicing; D015032:Zinc
D001426:Bacterial Proteins; D015032:Zinc