Identification and characterization of a family of toxin–antitoxin systems related to the Enterococcus faecalis plasmid pAD1 par addiction module

The par locus of the Enterococcus faecalis plasmid pAD1 is an RNA-regulated addiction module encoding the peptide toxin Fst. Homology searches revealed that Fst belongs to a family of at least nine related peptides encoded on the chromosomes and plasmids of six different Gram-positive bacterial species. Comparison of an alignment of these peptides with the results of a saturation mutagenesis analysis indicated regions of the peptides important for biological function. Examination of the genetic context of the fst genes revealed that all of these peptides are encoded within par-like loci with conserved features similar to pAD1 par. All four Ent. faecalis family members were demonstrated to produce the expected toxin-encoding and regulatory RNA products. The locus from the Ent. faecalis plasmid pAMS1 was demonstrated to function as an addiction module and Fst was shown to be toxic to Staphylococcus aureus, suggesting that a plasmid-encoded module in that species is performing the same function. Thus, the pAD1-encoded par locus appears to be the prototype of a family of related loci found in several Gram-positive species.

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Identification and characterization of UDP-N-acetylenolpyruvylglucosamine reductase (MurB) from the Gram-positive pathogen Streptococcus pneumoniae

Biochemical Journal ◽

10.1042/0264-6021:3550431 ◽

2001 ◽

Vol 355 (2) ◽

pp. 431 ◽

Cited By ~ 5

Author(s):

Daniel R. SYLVESTER ◽

Emilio ALVAREZ ◽

Arun PATEL ◽

Kapila RATNAM ◽

Howard KALLENDER ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Gram Positive ◽

Identification And Characterization

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Identification and characterization of genes encoding sex pheromone cAM373 activity in Enterococcus faecalis and Staphylococcus aureus

Molecular Microbiology ◽

10.1046/j.1365-2958.2002.02922.x ◽

2002 ◽

Vol 44 (3) ◽

pp. 803-817 ◽

Cited By ~ 50

Author(s):

Susan E. Flannagan ◽

Don B. Clewell

Keyword(s):

Staphylococcus Aureus ◽

Sex Pheromone ◽

Enterococcus Faecalis ◽

Genes Encoding ◽

Identification And Characterization ◽

And Staphylococcus Aureus

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Identification and Characterization of Clinically Isolated Biofilm-forming Gram-positive Rods from Teeth Associated with Persistent Apical Periodontitis

Journal of Endodontics ◽

10.1016/j.joen.2008.11.032 ◽

2009 ◽

Vol 35 (3) ◽

pp. 347-352 ◽

Cited By ~ 10

Author(s):

Kazuyoshi Yamane ◽

Kan Ogawa ◽

Masahiro Yoshida ◽

Hiroyuki Hayashi ◽

Toshio Nakamura ◽

...

Keyword(s):

Apical Periodontitis ◽

Gram Positive ◽

Identification And Characterization

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Plasmid-mediated trimethoprim-resistance in Staphylococcus aureus. Characterization of the first gram-positive plasmid dihydrofolate reductase (type S1)

Biochemical Journal ◽

10.1042/bj2430309 ◽

1987 ◽

Vol 243 (1) ◽

pp. 309-312 ◽

Cited By ~ 15

Author(s):

H K Young ◽

R A Skurray ◽

S G B Amyes

Keyword(s):

Staphylococcus Aureus ◽

Dihydrofolate Reductase ◽

Specific Activity ◽

Gram Positive ◽

Heat Stable ◽

Dihydrofolate Reductases ◽

High Degree ◽

Moderately Resistant ◽

Identification And Characterization

The trimethoprim-resistance gene located on plasmid pSK1, originally identified in a multi-resistant Staphylococcus aureus from Australia, encodes the production of a dihydrofolate reductase (type S1), which confers a high degree of resistance to its host and is quite unlike any plasmid-encoded dihydrofolate reductase hitherto described. It has a low Mr (19,700) and has a higher specific activity than the constitutive Gram-negative plasmid dihydrofolate reductases. The type S1 enzyme is heat-stable and has a relatively low affinity for the substrate, dihydrofolate (Km 10.8 microM). It is moderately resistant to trimethoprim, and is competitively inhibited by this drug with an inhibitor-binding constant of 11.6 microM. This is the first identification and characterization of a plasmid-encoded trimethoprim-resistant dihydrofolate reductase derived from a Gram-positive species.

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Characterization of a β-lactamase that contributes to intrinsic β-lactam resistance inClostridioides difficile

10.1101/630020 ◽

2019 ◽

Cited By ~ 1

Author(s):

Brindar K. Sandhu ◽

Adrianne N. Edwards ◽

Sarah E. Anderson ◽

Emily C. Woods ◽

Shonna M. McBride

Keyword(s):

Membrane Protein ◽

Unknown Function ◽

Signal Sequence ◽

Bacterial Species ◽

Resistance Mechanism ◽

Regulatory System ◽

Gram Positive ◽

Clostridioides Difficile ◽

Antibiotic Associated Diarrhea

ABSTRACTClostrididioides difficilecauses severe antibiotic-associated diarrhea and colitis.C. difficileis an anaerobic, Gram-positive spore former that is highly resistant to β-lactams, the most commonly prescribed antibiotics. The resistance ofC. difficileto β-lactam antibiotics allows the pathogen to replicate and cause disease in antibiotic-treated patients. However, the mechanisms of β-lactam resistance inC. difficileare not fully understood. Our data reinforce prior evidence thatC. difficileproduces a β-lactamase, which is a common β-lactam resistance mechanism found in other bacterial species. We identified an operon encoding a lipoprotein of unknown function and a β-lactamase that was greatly induced in response to several classes of β-lactam antibiotics. An in-frame deletion of the operon abolished β-lactamase activity inC. difficilestrain 630Δermand resulted in decreased resistance to the β-lactam ampicillin. We found that the activity of this β-lactamase, herein named BlaD, is dependent upon the redox state of the enzyme. In addition, we observed that transport of BlaD out of the cytosol and to the cell surface is facilitated by an N-terminal signal sequence. Our data demonstrate that a co-transcribed lipoprotein, BlaX, aids in BlaD activity. Further, we identified a conserved BlaRI regulatory system and demonstrated via insertional disruption that BlaRI controls transcription of theblaXDoperon in response to β-lactams. These results provide support for the function of a β-lactamase inC. difficileantibiotic resistance, and reveal the unique roles of a co-regulated lipoprotein and reducing environment in β-lactamase activity.IMPORTANCEClostridioides difficileis an anaerobic, gastrointestinal human pathogen. One of the highest risk factors for contractingC. difficileinfection is antibiotic treatment, which causes microbiome dysbiosis.C. difficileis resistant to β-lactam antibiotics, the most commonly prescribed class of antibiotics.C. difficileproduces a recently discovered β-lactamase, which cleaves and inactivates numerous β-lactams. In this study, we report the contribution of this anaerobic β-lactamase to ampicillin resistance inC. difficile, as well as the transcriptional regulation of the gene,blaD, by a BlaRI system. In addition, our data demonstrate co-transcription ofblaDwithblaX, which encodes a membrane protein of previously unknown function. Furthermore, we provide evidence that BlaX enhances β-lactamase activity in a portion ofC. difficilestrains. This study demonstrates a novel interaction between a β-lactamase and a membrane protein in a Gram-positive pathogen, and due to the anaerobic nature of the β-lactamase activity, suggests that more β-lactamases are yet to be identified in other anaerobes.

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Identification and characterization of two amylase producing bacteria Cellulosimicrobium sp. and Demequina sp. isolated from marine organisms

Journal of Agricultural and Marine Sciences [JAMS] ◽

10.24200/jams.vol20iss0pp8-15 ◽

2015 ◽

Vol 20 ◽

pp. 8 ◽

Cited By ~ 2

Author(s):

Laila S.H. Al-Naamani ◽

Sergey Dobretsov ◽

Jamal Al-Sabahi ◽

Bassam Soussi

Keyword(s):

Cell Growth ◽

Bacterial Species ◽

Marine Organisms ◽

Ulva Rigida ◽

Wide Range ◽

Amylase Production ◽

Maximum Cell ◽

Commercial Applications ◽

Identification And Characterization

Marine sources have been known to yield novel compounds with a wide range of bioactivity with various commercial applications. In this study, the abilities of bacteria isolated from eight marine organisms to produce α-amylase were examined. All eight organisms were found to harbor amylase producing bacteria. Two bacterial species isolated from the green alga Ulva rigida and the sponge Mycale sp. were further identified and their α-amylases were purified and characterized. The bacterial species isolated from U. rigida and Mycale sp. were identified by DNA sequencing as Cellulosimicrobium sp. and Demequina sp., respectively. Cellulosimicrobium sp. obtained maximum cell growth and amylase production at 29.C and in the presence of lactose as a carbon source. Optimal cell growth and amylase production by Demequina sp. was observed at 35.C. While lactose enhanced cell growth of Demequina sp., maximum amylase production was found when fructose and glycerol were the available sources of carbon. Both strains grew better in the presence of tryptone, whilst peptone stimulated amylase production. Maximal cell growth and amylase production by both of the strains was found at a medium salinity of 3% NaCl.

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Molecular Characterization of Zinc (Zn) Resistant Bacteria in Banger River, Pekalongan, Indonesia

Biosaintifika Journal of Biology & Biology Education ◽

10.15294/biosaintifika.v10i3.15835 ◽

2018 ◽

Vol 10 (3) ◽

pp. 622-628

Author(s):

Fitri Arum Sasi ◽

Hermin Pancasakti Kusumaningrum ◽

Anto Budiharjo

Keyword(s):

Bacterial Species ◽

Selective Medium ◽

Resistant Bacteria ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Indigenous Bacteria ◽

Gram Positive Bacteria ◽

Sequences Analysis

Indigenous bacteria are able to remove the metals contamination in environment. This study aimed to assess the resistance of bacterial species to Zinc (Zn) in Banger River, Pekalongan City. The bacteria from three different parts of Banger River were isolated and inoculated in Zn-selective medium. Then, molecular identification to determine the bacteria species was conducted using polymerase chain reaction (PCR) by applying forward-reverse 16SrRNA gene primers. The sequences analysis was conducted using MUSCLE and MEGA6. There were seven dominant species that possibly resistant to Zn. Approximately, every isolate could reach more than 95 % from 2000 ppm of Zn in the medium. The higher absorption of Zn was found in Z5 isolate. The seven bacteria species were clustered into nine genera i.e. Klebsiela, Xenorhabdus, Cronobacter, Enterobacter, Escherichia, Shigella and Sporomusa known as Gram Negative bacteria and Clostridium and Bacillus as Gram Positive bacteria. In Gram Positive bacteria, especially Bacillus sp, carboxyl group in peptidoglycan play a role as metal binder. In Gram-negative bacteria, lipopolysaccharide (LPS) which is highly anionic component on the outer membrane, able to catch the Zn. Besides that, Enterobacter activates endogen antioxidants such as glutathione peroxidase (GSHPx), glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD). The research found there was possible seven novel indigenous bacteria species in Banger that able to remove Zn from the sediment extremely. This finding can be developed as an eco-friendly approach to reduce metals pollution using local microorganisms.

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