scholarly journals The iron-dependent repressor YtgR is a tryptophan-dependent attenuator of the trpRBA operon in Chlamydia trachomatis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nick D. Pokorzynski ◽  
Nathan D. Hatch ◽  
Scot P. Ouellette ◽  
Rey A. Carabeo
Keyword(s):  
Chlamydia Trachomatis ◽  
Intergenic Region ◽  
Transcription Termination ◽  
Alternative Promoter ◽  
Open Reading Frames ◽  
Alternative Strategy ◽  
Fundamental Importance ◽  
Operator Sequence ◽  
Reading Frames

AbstractThe trp operon of Chlamydia trachomatis is organized differently from other model bacteria. It contains trpR, an intergenic region (IGR), and the biosynthetic trpB and trpA open-reading frames. TrpR is a tryptophan-dependent repressor that regulates the major promoter (PtrpR), while the IGR harbors an alternative promoter (PtrpBA) and an operator sequence for the iron-dependent repressor YtgR to regulate trpBA expression. Here, we report that YtgR repression at PtrpBA is also dependent on tryptophan by regulating YtgR levels through a rare triple-tryptophan motif (WWW) in the YtgCR precursor. Inhibiting translation during tryptophan limitation at the WWW motif subsequently promotes Rho-independent transcription termination of ytgR, thereby de-repressing PtrpBA. Thus, YtgR represents an alternative strategy to attenuate trpBA expression, expanding the repertoire for trp operon attenuation beyond TrpL- and TRAP-mediated mechanisms described in other bacteria. Furthermore, repurposing the iron-dependent repressor YtgR underscores the fundamental importance of maintaining tryptophan-dependent attenuation of the trpRBA operon.

scholarly journals Regulation of an iron-dependent repressor by tryptophan availability attenuates transcription of the tryptophan salvage genes in Chlamydia trachomatis

2020 ◽  
Author(s):  
Nick D. Pokorzynski ◽  
Nathan D. Hatch ◽  
Scot P. Ouellette ◽  
Rey A. Carabeo
Keyword(s):  
Chlamydia Trachomatis ◽  
Intergenic Region ◽  
Transcription Termination ◽  
Open Reading Frame ◽  
Independent Manner ◽  
Reading Frame ◽  
E Coli ◽  
Genetic Organization ◽  
Operator Sequence ◽  
Analogous Function

The trp operon of Chlamydia trachomatis has a genetic organization that is distinct from other model bacteria. The operon contains the trpR open-reading frame (ORF), an intergenic region (IGR), and the trpB and trpA ORFs. TrpR mediates tryptophan-dependent regulation of the operon from the major promoter upstream of trpR(PtrpR). We recently reported that trpBA is additionally regulated by the iron-dependent repressor YtgR via an operator sequence within the IGR upstream of an alternative promoter for TrpR-independent trpBA expression (PtrpBA). Here we report that YtgR repression of PtrpBA is also dependent on tryptophan levels via a rare triple-tryptophan motif (WWW) in the N-terminal permease domain of the YtgCR precursor. Tryptophan limitation inhibits translation at the WWW motif and subsequently promotes transcription termination of ytgCR in a Rho-independent manner. This regulatory schematic resembles mechanisms of transcriptional attenuation for trp operons described in model bacteria, such as cis-attenuation by TrpL in E. coli or trans-attenuation by TRAP in B. subtilis. YtgR performs an analogous function by sensing both iron and tryptophan levels, with the latter highlighting the unique strategy of Chlamydia to retain a trans-attenuator mechanism for regulating expression of the trpRBA operon.

scholarly journals Characterization of Chlamydia trachomatis Plasmid-Encoded Open Reading Frames

2013 ◽  
Vol 195 (17) ◽  
pp. 3819-3826 ◽  
Author(s):  
S. Gong ◽  
Z. Yang ◽  
L. Lei ◽  
L. Shen ◽  
G. Zhong
Keyword(s):  
Chlamydia Trachomatis ◽  
Open Reading Frames ◽  
Reading Frames

scholarly journals Characterization of the Gene Cassette Required for Biosynthesis of the (α1→6)-LinkedN-Acetyl-d-Mannosamine-1-Phosphate Capsule of Serogroup A Neisseria meningitidis

1998 ◽  
Vol 180 (6) ◽  
pp. 1533-1539 ◽  
Author(s):  
John S. Swartley ◽  
Li-Jun Liu ◽  
Yoon K. Miller ◽  
Larry E. Martin ◽  
Srilatha Edupuganti ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Intergenic Region ◽  
Gene Cassette ◽  
Amino Acid Identity ◽  
Open Reading Frames ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rt Pcr ◽  
Capsule Production ◽  
Reading Frames

ABSTRACT The (α1→6)-linkedN-acetyl-d-mannosamine-1-phosphate meningococcal capsule of serogroup A Neisseria meningitidisis biochemically distinct from the sialic acid-containing capsules produced by other disease-associated meningococcal serogroups (e.g., B, C, Y, and W-135). We defined the genetic cassette responsible for expression of the serogroup A capsule. The cassette comprised a 4,701-bp nucleotide sequence located between the outer membrane capsule transporter gene, ctrA, and galE, encoding the UDP-glucose-4-epimerase. Four open reading frames (ORFs) not found in the genomes of the other meningococcal serogroups were identified. The first serogroup A ORF was separated from ctrA by a 218-bp intergenic region. Reverse transcriptase (RT) PCR and primer extension studies of serogroup A mRNA showed that all four ORFs were cotranscribed in the opposite orientation to ctrA and that transcription of the ORFs was initiated from the intergenic region by a ς-70-type promoter that overlapped the ctrA promoter. The first ORF exhibited 58% amino acid identity with the UDP-N-acetyl-d-glucosamine (UDP-GlcNAc) 2-epimerase of Escherichia coli, which is responsible for the conversion of UDP-GlcNAc into UDP-N-acetyl-d-mannosamine. Polar or nonpolar mutagenesis of each of the ORFs resulted in an abrogation of serogroup A capsule production as determined by colony immunoblots and enzyme-linked immunosorbent assay. Replacement of the serogroup A biosynthetic gene cassette with a serogroup B cassette by transformation resulted in capsule switching from a serogroup A capsule to a serogroup B capsule. These data indicate that assembly of the serogroup A capsule likely begins with monomeric UDP-GlcNAc and requires proteins encoded by three other genes found in the serogroup A N. meningitidis-specific operon located betweenctrA and galE.

An Origin of Transfer (oriT) on the Conjugative Element pRS01 from Lactococcus lactis subsp.lactis ML3

1998 ◽  
Vol 64 (4) ◽  
pp. 1541-1544 ◽  
Author(s):  
David A. Mills ◽  
Trevor G. Phister ◽  
Gary M. Dunny ◽  
Larry L. McKay
Keyword(s):  
Sequence Analysis ◽  
Lactococcus Lactis ◽  
Intergenic Region ◽  
Inverted Repeat ◽  
Previous Analysis ◽  
Open Reading Frames ◽  
Wild Type ◽  
Derivatives Of ◽  
Reading Frames ◽  
Origin Of Transfer

ABSTRACT Previous analysis of the Tra1 region of the conjugative element pRS01 from Lactococcus lactis subsp. lactis ML3 suggested that an origin of transfer (oriT) was present. Deletion derivatives of this cloned Tra1 region were assayed for mobilization in the presence of the wild-type pRS01 element intrans. The pRS01 oriT was localized to a 446-nucleotide segment in the intergenic region between open reading frames ltrD and ltrE. Sequence analysis of this region revealed a cluster of direct and inverted repeat structures characteristic of oriT regions associated with other conjugative systems.

scholarly journals Transcription termination signals in the nin region of bacteriophage lambda: identification of Rho-dependent termination regions.

Genetics ◽  
1995 ◽  
Vol 140 (3) ◽  
pp. 875-887 ◽  
Author(s):  
S W Cheng ◽  
D L Court ◽  
D I Friedman
Keyword(s):  
Transcription Termination ◽  
Bacteriophage Lambda ◽  
Point Mutations ◽  
Open Reading Frames ◽  
Deletion Analysis ◽  
Testing System ◽  
Transcription Antitermination ◽  
Termination Activity ◽  
Phage Growth ◽  
Reading Frames

Abstract The approximately 3-kb nin region of bacteriophage lambda, located between genes P and Q contains transcription termination signals as well as 10 open reading frames. Deletions in the nin region frees phage growth from dependence on the lambda-encoded N-transcription antitermination system, conferring a Nin phenotype (N-independence). A subregion of nin, roc, is defined by a 1.9-kb deletion (delta roc) which partially frees lambda growth from the requirement for N antitermination. The roc region has strong transcription termination activity as assayed by a plasmid-based terminator testing system. We report the following features of the roc region: the biologically significant terminators in the roc region are Rho dependent, deletion analysis located the biologically significant termination signals to a 1.2 kb-segment of roc, and analysis of other deletions and point mutations in the roc region suggested at least two biologically significant regions of termination, tR3 (extending from bp 42020 to 42231) and tR4 (extending from bp 42630 to 42825).

scholarly journals Sequence Analysis of the Mouse RAG Locus lntergenic Region

1998 ◽  
Vol 5 (3) ◽  
pp. 215-222 ◽  
Author(s):  
F. E. Bertrand III ◽  
S. L. Olsona ◽  
D. A. Martin ◽  
G. E. Wu
Keyword(s):  
Germinal Center ◽  
Intergenic Region ◽  
Receptor Gene ◽  
Mouse Fibroblast ◽  
Open Reading Frames ◽  
Dna Rearrangement ◽  
Recombination Activating Genes ◽  
Fibroblast Line ◽  
Rag 1 ◽  
Reading Frames

The recombination activating genes RAG-1 and RAG-2 are highly conserved throughout evolution and are necessary and essential for the DNA rearrangement of antigen-receptor gene segments. These convergently transcribed genes are expressed primarily by developing B and T lineage cells. In addition, recent data suggest that the RAG locus can be reactivated in mouse germinal center B cells. Despite these well-defined patterns of expression, little is known about mechanism(s) regulating transcription of the RAG locus. Experiments with a mouse fibroblast line stably transfected with a genomic fragment of the RAG locus suggest that the intergenic region between RAG-1 and RAG-2 may contain information modulating RAG transcription. In order to begin testing this hypothesis, we have sequenced the 7.0-kb RAG intergenic region of the mouse. The sequence did not contain open reading frames larger than 60 amino acids. Analysis with GCG software identified several potential transcription-factor binding sequences within this region. Many of these are associated with transcriptional regulation of the Ig locus.

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