Open AccessCrystallization and preliminary X‐ray diffraction studies of sortase A from Streptococcus pneumoniae
Author(s) -
Misra Anurag,
Biswas Tora,
Das Sreetama,
Marathe Uttara,
Sehgal Devinder,
Roy Rajendra P.,
Suryanarayanarao Ramakumar
Publication year - 2011
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309111029952
Subject(s) - monoclinic crystal system , sortase , crystallography , streptococcus pneumoniae , bacterial adhesin , chemistry , crystallization , dimer , molecular replacement , virulence , crystal structure , biochemistry , bacterial protein , gene , organic chemistry , antibiotics
Sortases are cell‐membrane‐anchored cysteine transpeptidases that are essential for the assembly and anchoring of cell‐surface adhesins in Gram‐positive bacteria. Thus, they play critical roles in virulence, infection and colonization by pathogens. Sortases have been classified into four types based on their primary sequence and the target‐protein motifs that they recognize. All Gram‐positive bacteria express a class A housekeeping sortase (SrtA). Sortase A from Streptococcus pneumoniae (NP_358691) has been crystallized in two crystal forms. Diamond‐shaped crystals of ΔN 59 SrtA diffracted to 4.0 Å resolution and belonged to a tetragonal system with unit‐cell parameters a = b = 122.8, c = 86.5 Å, α = β = γ = 90°, while rod‐shaped crystals of ΔN 81 SrtA diffracted to 2.91 Å resolution and belonged to the monoclinic space group P 2 1 with unit‐cell parameters a = 66.8, b = 103.47, c = 74.79 Å, α = γ = 90, β = 115.65°. The Matthews coefficient ( V M = 2.77 Å 3 Da −1 ) with ∼56% solvent content suggested the presence of four molecules in the asymmetric unit for ΔN 81 SrtA. Also, a multi‐copy search using a monomer as a probe in the molecular‐replacement method resulted in the successful location of four sortase molecules in the asymmetric unit, with statistics R = 41.61, R free = 46.44, correlation coefficient (CC) = 64.31, CC free = 57.67.