A new family of phosphoinositide phosphatases in microorganisms: identification and biochemical analysis

BMC Genomics

Research Article

Lydia Tabernero¹  Ian S Roberts¹  Charis Saville¹  Hayley J Bennett¹  Nicola J Beresford² 

[1] Faculty of Life Sciences, Michael Smith Building, University of Manchester, M13 9PT, Manchester, UK;Faculty of Life Sciences, Michael Smith Building, University of Manchester, M13 9PT, Manchester, UK;Mycobacterial Research, National Institute for Medical Research, The Ridgeway, NW7 1AA, Mill Hill, London;

关键词: Malachite Green;    Protein Tyrosine Phosphatase;    Lipid Phosphatase;    Eukaryotic Sequence;    Nickel Affinity Chromatography;   

DOI  :  10.1186/1471-2164-11-457

 received in 2010-01-04, accepted in 2010-08-02,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundPhosphoinositide metabolism is essential to membrane dynamics and impinges on many cellular processes, including phagocytosis. Modulation of phosphoinositide metabolism is important for pathogenicity and virulence of many human pathogens, allowing them to survive and replicate in the host cells. Phosphoinositide phosphatases from bacterial pathogens are therefore key players in this modulation and constitute attractive targets for chemotherapy. MptpB, a virulence factor from Mycobacterium tuberculosis, has phosphoinositide phosphatase activity and a distinct active site P-loop signature HCXXGKDR that shares characteristics with eukaryotic lipid phosphatases and protein tyrosine phosphatases. We used this P-loop signature as a "diagnostic motif" to identify related putative phosphatases with phosphoinositide activity in other organisms.ResultsWe found more than 200 uncharacterised putative phosphatase sequences with the conserved signature in bacteria, with some related examples in fungi and protozoa. Many of the sequences identified belong to recognised human pathogens. Interestingly, no homologues were found in any other organisms including Archaea, plants, or animals. Phylogenetic analysis revealed that these proteins are unrelated to classic eukaryotic lipid phosphatases. However, biochemical characterisation of those from Listeria monocytogenes and Leishmania major, demonstrated that, like MptpB, they have phosphatase activity towards phosphoinositides. Mutagenesis studies established that the conserved Asp and Lys in the P-loop signature (HCXXGKD R) are important in catalysis and substrate binding respectively. Furthermore, we provide experimental evidence that the number of basic residues in the P-loop is critical in determining activity towards poly-phosphoinositides.ConclusionThis new family of enzymes in microorganisms shows distinct sequence and biochemical characteristics to classic eukaryotic lipid phosphatases and they have no homologues in humans. This study provides a foundation for examining the biological role of this new family of phosphatases and their potential as pharmaceutical targets against infectious diseases.

【 授权许可】

Unknown   
© Beresford et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.