Crystal structures of Val58Ile tryptophan repressor in a domain-swapped array in the presence and absence of l-tryptophan Sprenger Janina

Janina Sprenger, Catherine L. Lawson, Claes Von Wachenfeldt, Leila Lo Leggio, Jannette Carey

Research output: Contribution to journalArticlepeer-review

Abstract

The crystal structures of domain-swapped tryptophan repressor (TrpR) variant Val58Ile before and after soaking with the physiological ligand l-tryptophan (l-Trp) indicate that l-Trp occupies the same location in the domain-swapped form as in native dimeric TrpR and makes equivalent residue contacts. This result is unexpected because the ligand binding-site residues arise from three separate polypeptide chains in the domain-swapped form. This work represents the first published structure of a domain-swapped form of TrpR with l-Trp bound. The presented structures also show that the protein amino-terminus, whether or not it bears a disordered extension of about 20 residues, is accessible in the large solvent channels of the domain-swapped crystal form, as in the structures reported previously in this form for TrpR without N-terminal extensions. These findings inspire the exploration of l-Trp analogs and N-terminal modifications as labels to orient guest proteins that cannot otherwise be crystallized in the solvent channels of crystalline domain-swapped TrpR hosts for potential diffraction analysis.

Original languageEnglish (US)
Pages (from-to)215-225
Number of pages11
JournalActa Crystallographica Section F:Structural Biology Communications
Volume77
DOIs
StatePublished - Jul 1 2021

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Genetics
  • Condensed Matter Physics

Keywords

  • crystalline protein gel
  • domain swapping
  • fragment-based screening
  • hostal system
  • ligand binding
  • molecular baits
  • Val58Ile tryptophan repressor

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