title: Heterogeneous nucleation is required for crystallization of the ZnuA domain of pneumococcal AdcA.
abstract: Zn(2+) is an essential nutrient for all known forms of life. In the major human pathogen Streptococcus pneumoniae, the acquisition of Zn(2+) is facilitated by two Zn(2+)-specific solute-binding proteins: AdcA and AdcAII. To date, there has been a paucity of structural information on AdcA, which has hindered a deeper understanding of the mechanism underlying pneumococcal Zn(2+) acquisition. Native AdcA consists of two domains: an N-terminal ZnuA domain and a C-terminal ZinT domain. In this study, the ZnuA domain of AdcA was crystallized. The initial crystals of the ZnuA-domain protein were obtained using dried seaweed as a heterogeneous nucleating agent. No crystals were obtained in the absence of the heterogeneous nucleating agent. These initial crystals were subsequently used as seeds to produce diffraction-quality crystals. The crystals diffracted to 2.03 Å resolution and had the symmetry of space group P1. This study demonstrates the utility of heterogeneous nucleation. The solution of the crystal structures will lead to further understanding of Zn(2+) acquisition by S. pneumoniae.
authors.affiliation: School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
authors.forename: Zhenyao
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Jacqueline R
authors.initials: JR
authors.lastname: Morey
authors.affiliation: Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: McDevitt
authors.affiliation: School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
authors.forename: Boštjan
authors.initials: B
authors.lastname: Kobe
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D003460:Crystallization; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D013296:Streptococcus pneumoniae / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; C114936:AdcA protein, Streptococcus; D001426:Bacterial Proteins
keywords: AdcA; Streptococcus pneumoniae; Zn2+; ZnuA; heterogeneous nucleation; seaweed; solute-binding protein