Structural basis for sulfur relay to RNA mediated by heterohexameric TusBCD complex

Structure. 2006 Feb;14(2):357-66. doi: 10.1016/j.str.2005.11.009.


Uridine at wobble position 34 of tRNA(Lys), tRNA(Glu), and tRNA(Gln) is exclusively modified into 2-thiouridine (s2U), which is crucial for both precise codon recognition and recognition by the cognate aminoacyl-tRNA synthetases. Recent Escherichia coli genetic studies revealed that the products of five novel genes, tusABCDE, function in the s2U modification. Here, we solved the 2.15 angstroms crystal structure of the E. coli TusBCD complex, a sulfur transfer mediator, forming a heterohexamer composed of a dimer of the heterotrimer. Structure-based sequence alignment suggested two putative active site Cys residues, Cys79 (in TusC) and Cys78 (in TusD), which are exposed on the hexameric complex. In vivo mutant analyses revealed that only Cys78, in the TusD subunit, participates in sulfur transfer during the s2U modification process. Since the single Cys acts as a catalytic residue, we proposed that TusBCD mediates sulfur relay via a putative persulfide state of the TusD subunit.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Cysteine / chemistry
  • Cysteine / genetics
  • DNA Mutational Analysis
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Subunits / chemistry
  • RNA, Transfer / chemistry*
  • Sequence Alignment
  • Thiouridine / analogs & derivatives*
  • Thiouridine / chemistry


  • 2-thiouridine
  • Escherichia coli Proteins
  • Protein Subunits
  • TusB protein, E coli
  • TusC protein, E coli
  • TusD protein, E coli
  • tus protein, E coli
  • Thiouridine
  • RNA, Transfer
  • Cysteine

Associated data

  • PDB/2D1P