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Treponema denticola TroR is a manganese- and iron-dependent transcriptional repressor.

Brett PJ, Burtnick MN, Fenno JC, Gherardini FC - Mol. Microbiol. (2008)

Bottom Line: Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroR(Td)) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members.In addition, we demonstrate that although TroR(Td) possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroR(Td).Based upon these findings, we propose that TroR(Td) represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA.

ABSTRACT
Treponema denticola harbours a genetic locus with significant homology to most of the previously characterized Treponema pallidum tro operon. Within this locus are five genes (troABCDR) encoding for the components of an ATP-binding cassette cation-transport system (troABCD) and a DtxR-like transcriptional regulator (troR). In addition, a sigma(70)-like promoter and an 18 bp region of dyad symmetry were identified upstream of the troA start codon. This putative operator sequence demonstrated similarity to the T. pallidum TroR (TroR(Tp)) binding sequence; however, the position of this motif with respect to the predicted tro promoters differed. Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroR(Td)) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members. In the present study, we show that TroR(Td) is a manganese- and iron-dependent transcriptional repressor using Escherichia coli reporter constructs and in T. denticola. In addition, we demonstrate that although TroR(Td) possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroR(Td). Based upon these findings, we propose that TroR(Td) represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete.

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Genetic organization of the T. pallidum and the T. denticola tro operons and sequence alignment of the T. pallidum and T. denticola tro P/O regions located immediately upstream of the troA ORFs. troA is predicted to encode a periplasmic binding protein; troB is predicted to encode the ATP-binding component, while troC and troD are predicted to encode the membrane components of ABC transporters; troR is homologous to a number of genes encoding Gram-positive iron-activated repressor proteins including DtxR and SirR; gpm encodes the glycolytic pathway enzyme, phosphoglycerate mutase. The σ70-like promoters (−10 and −35 sequences) are indicated in bold (T. pallidum) or underlined (T. denitcola). The 18 bp operator motifs are highlighted in grey. Sequence identity between the operators is indicated by vertical lines. Putative ribosome binding sites are in bold (T. pallidum) or underlined (T. denitcola) and indicated by SD. The troA start codons are indicated by boxes.
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fig01: Genetic organization of the T. pallidum and the T. denticola tro operons and sequence alignment of the T. pallidum and T. denticola tro P/O regions located immediately upstream of the troA ORFs. troA is predicted to encode a periplasmic binding protein; troB is predicted to encode the ATP-binding component, while troC and troD are predicted to encode the membrane components of ABC transporters; troR is homologous to a number of genes encoding Gram-positive iron-activated repressor proteins including DtxR and SirR; gpm encodes the glycolytic pathway enzyme, phosphoglycerate mutase. The σ70-like promoters (−10 and −35 sequences) are indicated in bold (T. pallidum) or underlined (T. denitcola). The 18 bp operator motifs are highlighted in grey. Sequence identity between the operators is indicated by vertical lines. Putative ribosome binding sites are in bold (T. pallidum) or underlined (T. denitcola) and indicated by SD. The troA start codons are indicated by boxes.

Mentions: Analysis of the T. denticola ATCC 35405 genome sequence revealed the presence of a genetic locus demonstrating significant similarity to the T. pallidum tro operon. In T. denticola, the tro operon consists of five open reading frames: troA, troB, troC, troD and troR. This operon is predicted to encode the components of an ABC cation-transport system composed of TroA, a solute-binding protein; TroB, an ATPase; TroC and TroD, cytoplasmic membrane permeases; and TroR, a metal-dependent transcriptional regulator (Hardham et al., 1997). In contrast to T. pallidum, however, gpm encoding the glycolytic pathway enzyme, phosphoglycerate mutase is absent and the genes flanking the operons are not conserved (Fig. 1). Results of comparative analyses of the tro operons from these two organisms are shown in Table 1. The troABCD orthologues are highly similar in both species; however, unlike T. pallidum TroR (TroRTp), TroRTd harbours a 70-amino-acid C-terminal extension.


Treponema denticola TroR is a manganese- and iron-dependent transcriptional repressor.

Brett PJ, Burtnick MN, Fenno JC, Gherardini FC - Mol. Microbiol. (2008)

Genetic organization of the T. pallidum and the T. denticola tro operons and sequence alignment of the T. pallidum and T. denticola tro P/O regions located immediately upstream of the troA ORFs. troA is predicted to encode a periplasmic binding protein; troB is predicted to encode the ATP-binding component, while troC and troD are predicted to encode the membrane components of ABC transporters; troR is homologous to a number of genes encoding Gram-positive iron-activated repressor proteins including DtxR and SirR; gpm encodes the glycolytic pathway enzyme, phosphoglycerate mutase. The σ70-like promoters (−10 and −35 sequences) are indicated in bold (T. pallidum) or underlined (T. denitcola). The 18 bp operator motifs are highlighted in grey. Sequence identity between the operators is indicated by vertical lines. Putative ribosome binding sites are in bold (T. pallidum) or underlined (T. denitcola) and indicated by SD. The troA start codons are indicated by boxes.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2628430&req=5

fig01: Genetic organization of the T. pallidum and the T. denticola tro operons and sequence alignment of the T. pallidum and T. denticola tro P/O regions located immediately upstream of the troA ORFs. troA is predicted to encode a periplasmic binding protein; troB is predicted to encode the ATP-binding component, while troC and troD are predicted to encode the membrane components of ABC transporters; troR is homologous to a number of genes encoding Gram-positive iron-activated repressor proteins including DtxR and SirR; gpm encodes the glycolytic pathway enzyme, phosphoglycerate mutase. The σ70-like promoters (−10 and −35 sequences) are indicated in bold (T. pallidum) or underlined (T. denitcola). The 18 bp operator motifs are highlighted in grey. Sequence identity between the operators is indicated by vertical lines. Putative ribosome binding sites are in bold (T. pallidum) or underlined (T. denitcola) and indicated by SD. The troA start codons are indicated by boxes.
Mentions: Analysis of the T. denticola ATCC 35405 genome sequence revealed the presence of a genetic locus demonstrating significant similarity to the T. pallidum tro operon. In T. denticola, the tro operon consists of five open reading frames: troA, troB, troC, troD and troR. This operon is predicted to encode the components of an ABC cation-transport system composed of TroA, a solute-binding protein; TroB, an ATPase; TroC and TroD, cytoplasmic membrane permeases; and TroR, a metal-dependent transcriptional regulator (Hardham et al., 1997). In contrast to T. pallidum, however, gpm encoding the glycolytic pathway enzyme, phosphoglycerate mutase is absent and the genes flanking the operons are not conserved (Fig. 1). Results of comparative analyses of the tro operons from these two organisms are shown in Table 1. The troABCD orthologues are highly similar in both species; however, unlike T. pallidum TroR (TroRTp), TroRTd harbours a 70-amino-acid C-terminal extension.

Bottom Line: Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroR(Td)) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members.In addition, we demonstrate that although TroR(Td) possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroR(Td).Based upon these findings, we propose that TroR(Td) represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT 59840, USA.

ABSTRACT
Treponema denticola harbours a genetic locus with significant homology to most of the previously characterized Treponema pallidum tro operon. Within this locus are five genes (troABCDR) encoding for the components of an ATP-binding cassette cation-transport system (troABCD) and a DtxR-like transcriptional regulator (troR). In addition, a sigma(70)-like promoter and an 18 bp region of dyad symmetry were identified upstream of the troA start codon. This putative operator sequence demonstrated similarity to the T. pallidum TroR (TroR(Tp)) binding sequence; however, the position of this motif with respect to the predicted tro promoters differed. Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroR(Td)) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members. In the present study, we show that TroR(Td) is a manganese- and iron-dependent transcriptional repressor using Escherichia coli reporter constructs and in T. denticola. In addition, we demonstrate that although TroR(Td) possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroR(Td). Based upon these findings, we propose that TroR(Td) represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete.

Show MeSH
Related in: MedlinePlus