The first crystal structure of human RNase6 reveals a novel substrate binding and cleavage site arrangement
Prats, Guillem, 1942- (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)
Arranz Trullén, Javier (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)
Blanco, José A. (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)
Pulido, Daniel. (Imperial College London)
Nogués Bara, Maria Victòria (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)
Moussaoui, Mohammed. (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)
Boix i Borràs, Esther (Universitat Autònoma de Barcelona. Departament de Bioquímica i de Biologia Molecular)

Data:	2016
Resum:	Human RNase 6 is a cationic secreted protein that belongs to the RNase A superfamily. Its expression is induced in neutrophils and monocytes upon bacterial infection, suggesting a role in host defence. We present here the crystal structure of RNase 6 obtained at a 1. 72 Å resolution, being the first report for the protein threedimensional structure and thereby setting the basis for functional studies. The structure shows an overall kidney shaped globular fold shared with the other known family members. Three sulphate anions bound to RNase 6 were found, interacting to residues at the main active site (His15, His122 and Gln14) and cationic surface exposed residues (His36, His39, Arg66 and His67). Kinetic characterization, together with prediction of protein -nucleotide complexes by molecular dynamics, was applied to analyse the RNase 6 substrate nitrogenous base and phosphate selectivity. Our results reveal that, although RNase 6 is a moderate catalyst in comparison to the pancreatic RNase type, its structure includes lineage specific features that facilitate its activity towards polymeric nucleotide substrates. In particular, enzyme interactions at the substrate 5' end can provide an endonuclease type cleavage pattern. Interestingly, the RNase 6 crystal structure revealed a novel secondary active site conformed by the His36-His39 dyad that facilitates the polynucleotide substrate catalysis.
Ajuts:	Ministerio de Economía y Competitividad BFU2012-38695 Ministerio de Economía y Competitividad BES-2010-036238 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-728
Nota:	Altres ajuts: UAB/406-02-02/2013
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Protein crystallography ; RNase k6 ; RNase A superfamily ; Sulphate anion ; Kinetic characterization ; Molecular dynamics
Publicat a:	The Biochemical journal, 2016 , ISSN 0264-6021

DOI: 10.1042/BCJ20160245
PMID: 27013146

Postprint 48 p, 8.9 MB

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