The structural characterisation of a prophage encoded extracellular DNase from Streptococcus pyogenes

Korczynska, Justyna E. and Turkenburg, John P. and Taylor, Edward J. (2012) The structural characterisation of a prophage encoded extracellular DNase from Streptococcus pyogenes. Nucleic Acids Research, 40 (2). pp. 928-938. ISSN 0305-1048

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Full text URL: http://dx.doi.org/10.1093/nar/gkr789

Abstract

The pathogenic bacterium Group A Streptococcus pyogenes produces several extracellular DNases that have been shown to facilitate invasive infection by evading the human host immune system. DNases degrade the chromatin in neutrophil extracellular traps, enabling the bacterium to evade neutrophil capture. Spd1 is a type I, nonspecific ββα/metal-dependent nuclease from Streptococcus pyogenes, which is encoded by the SF370.1 prophage and is likely to be expressed as a result of prophage induction. We present here the X-ray structure of this DNase in the wild-type and Asn145Ala mutant form. Through structural and sequence alignments as well as mutagenesis studies, we have identified the key residues His121, Asn145 and Glu164, which are crucial for Spd1 nucleolytic activity and shown the active site constellation. Our wild-type structure alludes to the possibility of a catalytically blocked dimeric form of the protein. We have investigated the multimeric nature of Spd1 using size-exclusion chromatography with multi-angle light scattering (SEC-MALLS) in the presence and absence of the divalent metal ion Mg(2+), which suggests that Spd1 exists in a monomeric form in solution.

Item Type:Article
Keywords:spd1, Mf2, DNase, phage
Subjects:C Biological Sciences > C760 Biomolecular Science
Divisions:College of Science > School of Life Sciences
ID Code:6116
Deposited By: Edward Taylor
Deposited On:07 Sep 2012 18:06
Last Modified:29 Nov 2013 09:50

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