HlyU in @entity1838 is known to be the transcriptional activator of the hemolysin gene, HlyA and possibly a regulator of other virulence factors influencing growth, colonization and pathogenicity of this infective agent. Here we report the crystal structure of HlyU from @entity1838 N16961 (HlyU_Vc) at 1.8  . The protein, with five a-helices and three b-strands in the topology of a1-a2-b1-a3-a4-b2-b3-a5, forms a homodimer. Helices a3-a4 and a b sheet form the winged helix-turn-helix (wHTH) DNA-binding motif common to the transcription regulators of the SmtB/ArsR family. In spite of an overall fold similar to SmtB/ArsR family, it lacks any metal binding site seen in SmtB. A comparison of the dimeric interfaces showed that the one in SmtB is much larger and have salt bridges that can be disrupted to accommodate metal ions. A model of HlyU-DNA complex suggests bending of the DNA. @entity2569 38 in the structure was found to be modified as @entity32124 ; the oxidized form was not seen in another structure solved under reducing condition. Although devoid of any metal binding site, the presence of a @entity2569 residue exhibiting oxidation-reduction suggests the possibility of the existence of a redox switch in transcription regulation. A structure-based phylogenetic analysis of wHTH proteins revealed the segregation of metal and non-metal binding proteins as well as those in the latter group that are under redox control.

Crystal structure of HlyU, the hemolysin gene transcription activator, from XXXX N16961 and functional implications.

@entity2569 :: ('CHEBI:17561', 'Chemical') :: ['Cys'] @entity32124 :: ('CHEBI:37858', 'Chemical') :: ['sulfenic acid'] @entity1838 :: ('666', 'Species') :: ['V. cholerae', 'Vibrio cholerae']
@entity1838 :: (666,Species) :: ['Vibrio cholerae']
