Xin Ma

Publications (2)1.01 Total impact

• Article: Purification, crystallization and halide phasing of a Streptococcus agalactiae backbone pilin GBS80 fragment.

  Krishnan Vengadesan, Xin Ma, Prabhat Dwivedi, Hung Ton-That, Sthanam V L Narayana
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  ABSTRACT: The Gram-positive pathogen Streptococcus agalactiae or group B streptococcus (GBS) is the leading cause of bacterial septicemia, pneumonia and meningitis among neonates around the world. The pathogen assembles two types of pili on its surface, named PI-1 and PI-2, that mediate bacterial adherence to host cells. The GBS PI-1 pilus is formed by the major pilin GBS80, which forms the pilus shaft, and two minor pilins GBS104 and GBS52, which are incorporated into the pilus structure. While considerable structural information exists on Gram-negative pili, the structural study of Gram-positive pili is an emerging area of research. Here, the purification, crystallization and initial phasing of the 35 kDa major fragment of the backbone pilin GBS80 are reported. Crystals were obtained in two different space groups: P2(1) and C2. SAD data collected from an iodide-derivative crystal at the home source were used to obtain initial phases and interpretable electron-density maps.
  Acta Crystallographica Section F Structural Biology and Crystallization Communications 12/2010; 66(Pt 12):1666-9. · 0.51 Impact Factor
• Article: Preliminary crystallographic study of the Streptococcus agalactiae sortases, sortase A and sortase C1.

  Baldeep Khare, Alexandra Samal, Krishnan Vengadesan, K R Rajashankar, Xin Ma, I Hsiu Huang, Hung Ton-That, Sthanam V L Narayana
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  ABSTRACT: Sortases are cysteine transpeptidases that are essential for the assembly and anchoring of cell-surface adhesins in Gram-positive bacteria. In Streptococcus agalactiae (GBS), the pilin-specific sortase SrtC1 catalyzes the polymerization of pilins encoded by pilus island 1 (PI-1) and the housekeeping sortase SrtA is necessary for cell-wall anchoring of the resulting pilus polymers. These sortases are known to utilize different substrates for pilus polymerization and cell-wall anchoring; however, the structural correlates that dictate their substrate specificity have not yet been clearly defined. This report presents the expression, purification and crystallization of SrtC1 (SAG0647) and SrtA (SAG0961) from S. agalactiae strain 2603V/R. The GBS SrtC1 has been crystallized in three crystal forms and the GBS SrtA has been crystallized in one crystal form.
  Acta Crystallographica Section F Structural Biology and Crystallization Communications 09/2010; 66(Pt 9):1096-100. · 0.51 Impact Factor