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Crystal structure of bacteriophage T4 Spackle as determined by native SAD phasing
Author(s) -
Shi Ke,
Kurniawan Fredy,
Banerjee Surajit,
Moeller Nicholas H.,
Aihara Hideki
Publication year - 2020
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798320010979
Subject(s) - crystallography , bacteriophage , periplasmic space , capsid , dimer , chemistry , crystal structure , crystal (programming language) , escherichia coli , gene , biochemistry , organic chemistry , computer science , programming language
The crystal structure of a bacteriophage T4 early gene product, Spackle, was determined by native sulfur single‐wavelength anomalous diffraction (SAD) phasing using synchrotron radiation and was refined to 1.52 Å resolution. The structure shows that Spackle consists of a bundle of five α‐helices, forming a relatively flat disc‐like overall shape. Although Spackle forms a dimer in the crystal, size‐exclusion chromatography with multi‐angle light scattering shows that it is monomeric in solution. Mass spectrometry confirms that purified mature Spackle lacks the amino‐terminal signal peptide and contains an intramolecular disulfide bond, consistent with its proposed role in the periplasm of T4 phage‐infected Escherichia coli cells. The surface electrostatic potential of Spackle shows a strikingly bipolar charge distribution, suggesting a possible mode of membrane association and inhibition of the tail lysozyme activity in T4 bacteriophage superinfection exclusion.