tailieunhanh - Báo cáo khoa học: Comparison of human RNase 3 and RNase 7 bactericidal action at the Gram-negative and Gram-positive bacterial cell wall

The eosinophil cationic protein⁄RNase 3 and the skin-derived RNase 7 are two human antimicrobial RNases involved in host innate immunity. Both belong to the RNase A superfamily and share a high cationicity and a common structural architecture. | ỊFEBS Journal Comparison of human RNase 3 and RNase 7 bactericidal action at the Gram-negative and Gram-positive bacterial cell wall Marc Torrent Marina Badia Mohammed Moussaoui Daniel Sanchez M. Victoria Nogues and Ester Boix Departament de Bioquimica i Biologia Molecular Facultat Biociencies Universitat Autonoma de Barcelona Cerdanyola del Valles Spain Keywords antimicrobial proteins cell wall ECP immunity RNase 7 Correspondence E. Boix Departament de Bioquimica i Biologia Molecular Facultat de Biociencies Universitat Autonoma de Barcelona 08193 Cerdanyola del Valles Spain Fax 34 93 5811264 Tel 34 93 5814147 E-mail Received 19 November 2009 revised 25 January 2010 accepted 27 January 2010 doi The eosinophil cationic protein RNase 3 and the skin-derived RNase 7 are two human antimicrobial RNases involved in host innate immunity. Both belong to the RNase A superfamily and share a high cationicity and a common structural architecture. However they present significant divergence at their primary structures displaying either a high number of Arg or Lys residues respectively. Previous comparative studies with a membrane model revealed two distinct mechanisms of action for lipid bilayer disruption. We have now compared their bactericidal activity identifying some features that confer specificity at the bacterial cell wall level. RNase 3 displays a specific Escherichia coli cell agglutination activity which is not shared by RNase 7. The RNase 3 agglutination process precedes the bacterial death and lysis event. In turn RNase 7 can trigger the release of bacterial cell content without inducing any cell aggregation process. We hypothesize that the RNase 3 agglutination activity may depend on its high affinity for lipopolysaccharides and the presence of an N-terminal hydrophobic patch and thus could facilitate host clearance activity at the infection focus by phagocytic cells. The present study suggests that the membrane .