Identification and transcriptional analysis of a Treponema pallidum operon encoding a putative ABC transport system, an iron-activated repressor protein homolog, and a glycolytic pathway enzyme homolog

Gene. 1997 Sep 15;197(1-2):47-64. doi: 10.1016/s0378-1119(97)00234-5.


We have characterized a 5.2-kilobase (kb) putative transport related operon (tro) locus of Treponema pallidum subsp. pallidum (Nichols strain) (Tp) encoding six proteins: TroA, TroB, TroC, TroD, TroR and Phosphoglycerate mutase (Pgm). Four of these gene products (TroA-TroD) are homologous to members of the ATP-Binding Cassette (ABC) superfamily of bacterial transport proteins. TroA (previously identified as Tromp1) has significant sequence similarity to a family of Gram-negative periplasmic substrate-binding proteins and to a family of streptococcal proteins that may have dual roles as substrate binding proteins and adhesins. TroB is homologous to the ATP-binding protein component, whereas TroC and TroD are related to the hydrophobic membrane protein components of ABC transport systems. TroR is similar to Gram-positive iron-activated repressor proteins (DesR, DtxR, IdeR, and SirR). The last open reading frame (ORF) of the tro operon encodes a protein that is highly homologous to the glycolytic pathway enzyme, Pgm. Primer extension results demonstrated that the tro operon is transcribed from a sigma 70-type promoter element. Northern analysis and reverse transcriptase-polymerase chain reactions provided evidence for the presence of a primary 1-kb troA transcript and a secondary, less abundant, troA-pgm transcript. The tro operon is flanked by a Holliday structure DNA helicase homolog (upstream) and two ORFs representing a purine nucleoside phosphorylase homolog and tpp15, a previously characterized gene encoding a membrane lipoprotein (downstream). The presence of a complex operon containing a putative ABC transport system and a DtxR homolog indicates a possible linkage between transport and gene regulation in Tp.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / genetics*
  • Amino Acid Sequence
  • Base Sequence
  • Cloning, Molecular
  • Genes, Bacterial / genetics
  • Iron / pharmacology
  • Molecular Sequence Data
  • Open Reading Frames / genetics
  • Operon / genetics*
  • Periplasmic Binding Proteins*
  • Phosphoglycerate Mutase / genetics*
  • Promoter Regions, Genetic / genetics
  • RNA, Bacterial / analysis
  • RNA, Messenger / analysis
  • Repressor Proteins / genetics*
  • Restriction Mapping
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Treponema pallidum / genetics*


  • ATP-Binding Cassette Transporters
  • Periplasmic Binding Proteins
  • RNA, Bacterial
  • RNA, Messenger
  • Repressor Proteins
  • TroA protein, Treponema pallidum
  • Iron
  • Phosphoglycerate Mutase

Associated data

  • GENBANK/U55214