Identification of the EdcR Estrogen-Dependent Repressor in Caenibius tardaugens NBRC 16725: Construction of a Cellular Estradiol Biosensor

In this work, Caenibius tardaugens NBRC 16725 (strain ARI-1) (formerly Novosphingobium tardaugens) was isolated due to its capacity to mineralize estrogenic endocrine disruptors. Its genome encodes the edc genes cluster responsible for the degradation of 17β-estradiol, consisting of two putative operons (OpA and OpB) encoding the enzymes of the upper degradation pathway. Inside the edc cluster, we identified the edcR gene encoding a TetR-like protein. Genetic studies carried out with C. tardaugens mutants demonstrated that EdcR represses the promoters that control the expression of the two operons. These genetic analyses have also shown that 17β-estradiol and estrone, the second intermediate of the degradation pathway, are the true effectors of EdcR. This regulatory system has been heterologously expressed in Escherichia coli, foreseeing its use to detect estrogens in environmental samples. Genome comparisons have identified a similar regulatory system in the edc cluster of Altererythrobacter estronivorus MHB5, suggesting that this regulatory arrangement has been horizontally transferred to other bacteria.

Download Full-text

mcr-9, an Inducible Gene Encoding an Acquired Phosphoethanolamine Transferase in Escherichia coli, and Its Origin

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00965-19 ◽

2019 ◽

Vol 63 (9) ◽

Cited By ~ 23

Author(s):

Nicolas Kieffer ◽

Guilhem Royer ◽

Jean-Winoc Decousser ◽

Anne-Sophie Bourrel ◽

Mattia Palmieri ◽

...

Keyword(s):

Escherichia Coli ◽

Lipid A ◽

Acquired Resistance ◽

Regulatory System ◽

Amino Acid Identity ◽

Gene Encoding ◽

Content Type ◽

E Coli ◽

K 12 ◽

A Minor

ABSTRACT The plasmid-located mcr-9 gene, encoding a putative phosphoethanolamine transferase, was identified in a colistin-resistant human fecal Escherichia coli strain belonging to a very rare phylogroup, the D-ST69-O15:H6 clone. This MCR-9 protein shares 33% to 65% identity with the other plasmid-encoded MCR-type enzymes identified (MCR-1 to -8) that have been found as sources of acquired resistance to polymyxins in Enterobacteriaceae. Analysis of the lipopolysaccharide of the MCR-9-producing isolate revealed a function similar to that of MCR-1 by adding a phosphoethanolamine group to lipid A and subsequently modifying the structure of the lipopolysaccharide. However, a minor impact on susceptibility to polymyxins was noticed once the mcr-9 gene was cloned and produced in an E. coli K-12-derived strain. Nevertheless, we showed here that subinhibitory concentrations of colistin induced the expression of the mcr-9 gene, leading to increased MIC levels. This inducible expression was mediated by a two-component regulatory system encoded by the qseC and qseB genes located downstream of mcr-9. Genetic analysis showed that the mcr-9 gene was carried by an IncHI2 plasmid. In silico analysis revealed that the plasmid-encoded MCR-9 shared significant amino acid identity (ca. 80%) with the chromosomally encoded MCR-like proteins from Buttiauxella spp. In particular, Buttiauxella gaviniae was found to harbor a gene encoding MCR-BG, sharing 84% identity with MCR-9. That gene was neither expressed nor inducible in its original host, which was fully susceptible to polymyxins. This work showed that mcr genes may circulate silently and remain undetected unless induced by colistin.

Download Full-text

SOS-Independent Induction of dinB Transcription by β-Lactam-Mediated Inhibition of Cell Wall Synthesis in Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.187.4.1515-1518.2005 ◽

2005 ◽

Vol 187 (4) ◽

pp. 1515-1518 ◽

Cited By ~ 78

Author(s):

Tatiana Pérez-Capilla ◽

María-Rosario Baquero ◽

José-María Gómez-Gómez ◽

Alina Ionel ◽

Soledad Martín ◽

...

Keyword(s):

Escherichia Coli ◽

Cell Wall ◽

Dna Polymerase ◽

Frameshift Mutation ◽

Regulatory System ◽

Cell Wall Synthesis ◽

Gene Encoding ◽

Lactam Antibiotic ◽

Dna Polymerase Iv ◽

Different Levels

ABSTRACT Transcription of the dinB gene, encoding DNA polymerase IV, is induced by the inhibition of cell wall synthesis at different levels. Using the β-lactam antibiotic ceftazidime, a PBP3 inhibitor, as a model, we have shown that this induction is independent of the LexA/RecA regulatory system. Induction of dinB transcription mediated by ceftazidime produces an increase in the reversion of a +1 Lac frameshift mutation.

Download Full-text

Improvement of putrescine production through the arginine decarboxylase pathway in Escherichia coli K-12

AMB Express ◽

10.1186/s13568-021-01330-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kullathida Thongbhubate ◽

Kanako Irie ◽

Yumi Sakai ◽

Akane Itoh ◽

Hideyuki Suzuki

Keyword(s):

Escherichia Coli ◽

Amino Acid ◽

Amino Acid Residue ◽

Batch Fermentation ◽

Feedback Inhibition ◽

Arginine Decarboxylase ◽

Degradation Pathway ◽

Gene Encoding ◽

K 12 ◽

Utilization Pathway

AbstractIn the bio-based polymer industry, putrescine is in the spotlight for use as a material. We constructed strains of Escherichia coli to assess its putrescine production capabilities through the arginine decarboxylase pathway in batch fermentation. N-Acetylglutamate (ArgA) synthase is subjected to feedback inhibition by arginine. Therefore, the 19th amino acid residue, Tyr, of argA was substituted with Cys to desensitize the feedback inhibition of arginine, resulting in improved putrescine production. The inefficient initiation codon GTG of argA was substituted with the effective ATG codon, but its replacement did not affect putrescine production. The essential genes for the putrescine production pathway, speA and speB, were cloned into the same plasmid with argAATG Y19C to form an operon. These genes were introduced under different promoters; lacIp, lacIqp, lacIq1p, and T5p. Among these, the T5 promoter demonstrated the best putrescine production. In addition, disruption of the puuA gene encoding enzyme of the first step of putrescine degradation pathway increased the putrescine production. Of note, putrescine production was not affected by the disruption of patA, which encodes putrescine aminotransferase, the initial enzyme of another putrescine utilization pathway. We also report that the strain KT160, which has a genomic mutation of YifEQ100TAG, had the greatest putrescine production. At 48 h of batch fermentation, strain KT160 grown in terrific broth with 0.01 mM IPTG produced 19.8 mM of putrescine.

Download Full-text

The Atg8 Conjugation System Is Indispensable for Proper Development of Autophagic Isolation Membranes in Mice

Molecular Biology of the Cell ◽

10.1091/mbc.e08-03-0309 ◽

2008 ◽

Vol 19 (11) ◽

pp. 4762-4775 ◽

Cited By ~ 282

Author(s):

Yu-shin Sou ◽

Satoshi Waguri ◽

Jun-ichi Iwata ◽

Takashi Ueno ◽

Tsutomu Fujimura ◽

...

Keyword(s):

Essential Role ◽

Degradation Pathway ◽

Conjugation System ◽

Autophagosome Formation ◽

Gene Encoding ◽

Genetic Studies ◽

Evolutionarily Conserved ◽

Deficient Mice ◽

Mouse Genetic

Autophagy is an evolutionarily conserved bulk-protein degradation pathway in which isolation membranes engulf the cytoplasmic constituents, and the resulting autophagosomes transport them to lysosomes. Two ubiquitin-like conjugation systems, termed Atg12 and Atg8 systems, are essential for autophagosomal formation. In addition to the pathophysiological roles of autophagy in mammals, recent mouse genetic studies have shown that the Atg8 system is predominantly under the control of the Atg12 system. To clarify the roles of the Atg8 system in mammalian autophagosome formation, we generated mice deficient in Atg3 gene encoding specific E2 enzyme for Atg8. Atg3-deficient mice were born but died within 1 d after birth. Conjugate formation of mammalian Atg8 homologues was completely defective in the mutant mice. Intriguingly, Atg12–Atg5 conjugation was markedly decreased in Atg3-deficient mice, and its dissociation from isolation membranes was significantly delayed. Furthermore, loss of Atg3 was associated with defective process of autophagosome formation, including the elongation and complete closure of the isolation membranes, resulting in malformation of the autophagosomes. The results indicate the essential role of the Atg8 system in the proper development of autophagic isolation membranes in mice.

Download Full-text