Combining random microseed matrix screening and the magic triangle for the efficient structure solution of a potential lysin from bacteriophage P68

Jia Quyen Truong, Santosh Panjikar, Linda Shearwin-Whyatt, John B. Bruning, Keith E. Shearwin

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)


Two commonly encountered bottlenecks in the structure determination of a protein by X-ray crystallography are screening for conditions that give high-quality crystals and, in the case of novel structures, finding derivatization conditions for experimental phasing. In this study, the phasing molecule 5-amino-2,4,6-triiodoisophthalic acid (I3C) was added to a random microseed matrix screen to generate high-quality crystals derivatized with I3C in a single optimization experiment. I3C, often referred to as the magic triangle, contains an aromatic ring scaffold with three bound I atoms. This approach was applied to efficiently phase the structures of hen egg-white lysozyme and the N-terminal domain of the Orf11 protein from Staphylococcus phage P68 (Orf11 NTD) using SAD phasing. The structure of Orf11 NTD suggests that it may play a role as a virion-associated lysin or endolysin.

Original languageEnglish
Pages (from-to)670-681
Number of pages12
JournalActa Crystallographica Section D: Structural Biology
Publication statusPublished - Jul 2019
Externally publishedYes


  • crystallography
  • I3C
  • lysin
  • magic triangle
  • phasing
  • random microseed matrix screening
  • seeding

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