tailieunhanh - Báo cáo khoa học: The bactericidal action on Escherichia coli of ZF-RNase-3 is triggered by the suicidal action of the bacterium OmpT protease

ZF-RNase-3 is one of the RNases from zebrafish (Danio rerio) with special (. noncatalytic) properties. These include angiogenic and bactericidal activities. Given the interest of fish RNases as host-defense effectors, we studied the mechanism of the bactericidal action of ZF-RNase-3 onEscheri-chia coli as a model Gram-negative bacterium. | ỊFEBS Journal The bactericidal action on Escherichia coli of ZF-RNase-3 is triggered by the suicidal action of the bacterium OmpT protease Anna Zanfardino1 Elio Pizzo1 Antimo Di Maro2 Mario Varcamonti1 and Giuseppe D Alessio1 1 Dipartimento di Biologia Strutturale e Funzionale Universita di Napoli Federico II Napoli Italy 2 Dipartimento di Scienze della Vita Seconda Universita di Napoli Caserta Italy Keywords bactericidalactivity Danio rerio Escherichia coli RNase zebrafish Correspondence G. D Alessio Dipartimento di Biologia Strutturale e Funzionale University di Napoli Federico II Via Cintia 80126 Napoli Italy Fax 81 679 159 Tel 81 679 157 E-mail dalessio@ Received 17 December 2009 revised 4 February 2010 accepted 8 February 2010 doi ZF-RNase-3 is one of the RNases from zebrafish Danio rerio with special . noncatalytic properties. These include angiogenic and bactericidal activities. Given the interest of fish RNases as host-defense effectors we studied the mechanism of the bactericidal action of ZF-RNase-3 on Escherichia coli as a model Gram-negative bacterium. The results obtained indicate that the bactericidal activity of ZF-RNase-3 is not lost when its catalytic RNase activity is obliterated. On the other hand fully denatured ZF-RNase-3 conserves its bactericidal activity. When ZF-RNase-3 is added to E. coli cultures it is cleaved at a specific Arg-Arg peptide bond thus engendering two peptide fragments. The larger fragment residues 31-124 produced by proteolysis and reduction of a disulfide is recognized as the actual bactericidal agent. The protease responsible for the proteolytic attack has been identified with OmpT an outer membrane E. coli omptin protease. However the most remarkable result obtained in the present study is the finding that the microbicidal action of ZF-RNase-3 can be achieved only with the suicidal cooperation of the bacterium itself. Introduction The vertebrate RNase superfamily comprises .