Post-proteomic identification of a novel phage-encoded streptodornase, Sda1, in invasive M1T1 Streptococcus pyogenes

Aziz, R. K., Ismail, S. A. , Park, H.-W. and Kotb, M. (2004) Post-proteomic identification of a novel phage-encoded streptodornase, Sda1, in invasive M1T1 Streptococcus pyogenes. Molecular Microbiology, 54(1), pp. 184-197. (doi:10.1111/j.1365-2958.2004.04255.x) (PMID:15458415)

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Summary: The M1T1 strain remains the most frequently isolated strain from group A streptococcal (GAS) infection cases worldwide. We previously reported that M1T1 differs from the fully sequenced M1 SF370 strain. To better understand the reason for the persistence and increased virulence of M1T1, we analysed its secreted proteome and identified two virulence proteins that are not present in the sequenced M1 SF370 strain: streptococcal pyrogenic exotoxin A (SpeA) and a streptodornase D (SdaD) homologue. In the present study, we determined the nucleotide sequence of the M1T1 streptodornase and found that its deduced amino acid sequence is highly similar to other streptococcal streptodornases, and is most closely related to the SdaD of GAS strain M49. M1T1 Sda shares two highly conserved domains with several DNases and putative DNases in streptococci; however, it possesses a unique C‐terminal amino acid sequence. Thus, we named the protein Sda1, and we detected the presence of the sda1 gene in 16 M1T1 clinical isolates. The cloned and expressed Sda1 degrades both streptococcal and mammalian DNA at physiological pH. Amino acid similarity analyses of known GAS deoxyribonucleases suggest that Sda1 may be a chimeric protein created through recombination events. Moreover, a natural mutation that resulted in longer Sda1 and SdaD as compared to other GAS DNases was found to confer increased activity on the protein. Analysis of the sequences flanking sda1 determined that it is carried by a prophage or a prophage‐like element inserted in the tRNA‐Ser gene of M1T1 GAS. Ongoing studies in our laboratory aim to determine the contribution of Sda1 to the virulence of this globally disseminated M1T1 strain.

Item Type:Articles
Additional Information:This work was supported by Grant AI40198‐06 from NIH, National Institute of Allergy and Infectious Diseases (NIAID, to M.K.), by the Research and Development Office, Medical Research Service, Department of Veterans Affairs (Merit Award to M.K.), and by a UTHSC Center of Excellence in Genomics and Bioinformatics grant (to M.K. and R.K.A.). A poster containing a part of this work was awarded the ASM‐student travel grant in the 43rd ICAAC conference (Chicago, IL, 2003).
Glasgow Author(s) Enlighten ID:Ismail, Dr Shehab
Authors: Aziz, R. K., Ismail, S. A., Park, H.-W., and Kotb, M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Journal Name:Molecular Microbiology
ISSN (Online):1365-2958

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