Campylobacter jejuni Transcription and Iron Uptake
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Questions and Answers

What was the concentration of streptomycin where STM-sensitive growth was observed?

  • 1 – 8 μg/ml
  • 16 – 32 μg/ml
  • 0 – 1 μg/ml (correct)
  • 8 – 16 μg/ml

The ⌬1651–1656 and ⌬p19 mutants exhibited a bimodal growth phenotype.

False (B)

What effect did iron supplementation have on the MICs of the mutants?

Restored them to wild-type levels of 16 μg/ml.

The wild-type strain of C. jejuni showed a bimodal growth phenotype under streptomycin stress at concentrations of _______.

<p>0 to 8 μg/ml</p> Signup and view all the answers

How did the cell viability of C. jejuni strains change after H2O2 addition in MH alone?

<p>Decreased over time (C)</p> Signup and view all the answers

Match the mutant strains with their corresponding growth phenotype:

<p>⌬1651–1656 = Monomodal growth ⌬p19 = Monomodal growth Wild-type = Bimodal growth Complemented strains = Bimodal growth</p> Signup and view all the answers

There were no significant differences between the growth of the wild-type and mutant strains under oxidative stress.

<p>False (B)</p> Signup and view all the answers

What was the role of iron(III) citrate in the study?

<p>To supplement conditions under which C. jejuni was tested for growth.</p> Signup and view all the answers

What temperature was C. jejuni incubated microaerobically for optimal growth?

<p>38°C (C)</p> Signup and view all the answers

C. jejuni is primarily grown in Luria-Bertani broth for selection using kanamycin and chloramphenicol.

<p>True (A)</p> Signup and view all the answers

What is the purpose of adding extracts to the culture media for C. jejuni?

<p>To promote growth and biofilm formation.</p> Signup and view all the answers

C. jejuni cells were cultured in ____ broth at an OD600 of 0.25 for RNA preparation.

<p>MH-TV</p> Signup and view all the answers

Match the following components with their respective roles in the experiment:

<p>Cm = Selection antibiotic Km = Selection antibiotic MH-TV = Culture medium Extracts = Growth enhancement and biofilm formation</p> Signup and view all the answers

What volume of extract was combined in the MH-TV culture for testing?

<p>0.3 ml (C)</p> Signup and view all the answers

The planktonic cell concentration was measured from the surface of the liquid culture.

<p>False (B)</p> Signup and view all the answers

How were the biofilms quantified in the experiment?

<p>By dilution plating.</p> Signup and view all the answers

Which gene showed the greatest reduction in expression after 5 hours?

<p>C4-dicarboxylate ABC transporter (C)</p> Signup and view all the answers

The gene CJJ81176_0685 is associated with chemotaxis.

<p>False (B)</p> Signup and view all the answers

What is the significance of a P value less than 0.05 in this context?

<p>It indicates statistical significance of the gene expression changes.</p> Signup and view all the answers

CJJ81176_0033 is the locus tag for the gene responsible for __________ synthesis.

<p>glutamate</p> Signup and view all the answers

Match the following genes with their functions:

<p>CJJ81176_0184 = Hypothetical protein CJJ81176_0912 = Amino acid carrier protein CJJ81176_1350 = Fumarate reductase CJJ81176_1006 = Hypothetical protein</p> Signup and view all the answers

Which gene product is a major antigenic peptide?

<p>PEB3 (A)</p> Signup and view all the answers

The locus tag CJJ81176_1656 codes for a thioredoxin family protein.

<p>True (A)</p> Signup and view all the answers

What is the fold change of the gene CJJ81176_0315 after 20 minutes?

<p>-3.0</p> Signup and view all the answers

The gene CJJ81176_1386 is responsible for __________ reductase activity.

<p>fumarate</p> Signup and view all the answers

Which of the following genes is associated with sodium:alanine symporter function?

<p>CJJ81176_0941 (D)</p> Signup and view all the answers

What is the primary transcription start site for the 1649 –1656 genes located relative to the 1649 start codon?

<p>54 bases upstream (D)</p> Signup and view all the answers

The genes 1648 and 1657 are considered part of the operon consisting of genes 1649 –1656.

<p>False (B)</p> Signup and view all the answers

How many fully sequenced Campylobacter species contain components of the 1649 –1656 system?

<p>22</p> Signup and view all the answers

The homologous gene products of the 1649 –1656 system were most commonly found in members of the ______.

<p>Proteobacteria</p> Signup and view all the answers

Match the following bacterial genera with whether they carry the 1649 –1656 system on plasmids or chromosomes:

<p>Escherichia = Plasmids Klebsiella = Plasmids Shigella = Plasmids Campylobacter = Chromosomes</p> Signup and view all the answers

Which of the following species has not been associated with human illness?

<p>C. avium (A), C. helveticus (D)</p> Signup and view all the answers

The complete genome sequences of 33 phylogenetically diverse bacterial species showed homologues of genes 1649 –1656 exclusively in Actinobacteria.

<p>False (B)</p> Signup and view all the answers

What is the distance in base pairs between gene 1648 and the start codon of gene 1649?

<p>350</p> Signup and view all the answers

Which gene product is associated with the function of aspartate ammonia-lyase?

<p>aspA (D)</p> Signup and view all the answers

CJJ81176_1649 has a higher fold change than CJJ81176_1651.

<p>True (A)</p> Signup and view all the answers

What is the fold change for the gene product associated with the 'putative oxidoreductase subunit' after 5 hours?

<p>11.8</p> Signup and view all the answers

CJJ81176_0885 is a type of ______.

<p>cytochrome c</p> Signup and view all the answers

Match the following gene products with their functions:

<p>CJJ81176_1650 = Periplasmic iron binding protein CJJ81176_1391 = C4-dicarboxylate ABC transporter CJJ81176_1390 = Reactive intermediate/imine deaminase CJJ81176_0123 = Anaerobic C4-dicarboxylate membrane transporter DcuA</p> Signup and view all the answers

Which locus tag shows the highest fold change after 20 minutes?

<p>CJJ81176_0438 (C)</p> Signup and view all the answers

The gene CJJ81176_1392 is associated with cystathionine β-lyase.

<p>True (A)</p> Signup and view all the answers

What is the function of the gene product CJJ81176_1654?

<p>ATP-binding protein</p> Signup and view all the answers

CJJ81176_1393 encodes an ______.

<p>adenylosuccinate lyase</p> Signup and view all the answers

Which of the following genes is associated with anaerobic dimethyl sulfoxide reductase?

<p>CJJ81176_1570 (B)</p> Signup and view all the answers

Which of the following bacteria is associated with the case of enteritis in humans?

<p>Campylobacter lanienae (C)</p> Signup and view all the answers

Aspartase (AspA) is essential for bacteria to grow under aerobic conditions.

<p>False (B)</p> Signup and view all the answers

What is the primary function of the C4-dicarboxylate transporters in Campylobacter jejuni?

<p>Transport of C4-dicarboxylates for metabolic processes</p> Signup and view all the answers

___ is a novel succinic-acid-producing strain from the bovine rumen.

<p>Actinobacillus succinogenes sp.</p> Signup and view all the answers

Match the following bacterial species with their notable characteristics:

<p>Campylobacter jejuni = Amino acid-dependent growth Actinobacillus succinogenes = Succinic acid production Frischella perrara = Gammaproteobacterium from honeybee gut Campylobacter lanienae = Cause of enteritis in humans</p> Signup and view all the answers

What role does AspB (Cj0762) play in Campylobacter jejuni?

<p>It is essential for growth on glutamate. (D)</p> Signup and view all the answers

The complete genome sequence of Wolinella succinogenes has been analyzed.

<p>True (A)</p> Signup and view all the answers

Identify the main focus of the 2014 study on bacterial metabolism referenced.

<p>Bacterial methionine biosynthesis</p> Signup and view all the answers

Flashcards

Operon

A group of genes that are transcribed together as a single unit, meaning they are controlled by the same promoter and produce a single mRNA molecule.

Promoter

A region of DNA located upstream of a gene that binds regulatory proteins, controlling the transcription of the gene.

Fur box

A DNA sequence that binds the Fur protein, repressing transcription of downstream genes when iron levels are high.

Fur protein

A protein that regulates the expression of genes involved in iron metabolism.

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Primary transcription start site

The first gene in a set of genes that are transcribed together as an operon.

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Protein BLAST

A tool that compares protein sequences to find similar sequences in other organisms, helping to understand the function and evolution of genes.

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Campylobacter

A type of bacteria that can cause disease in humans, often associated with food poisoning.

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Plasmid

A type of bacterial genome that can transfer genetic information between bacteria.

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Bimodal growth phenotype

A type of bacterial growth where cell density increases rapidly at low concentrations of the antibiotic but then plateaus or even decreases at higher concentrations.

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Monomodal growth phenotype

A type of bacterial growth where cell density increases steadily as the concentration of the antibiotic increases.

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⌬1651–1656 mutation

A mutation in Campylobacter jejuni that affects its sensitivity to streptomycin and other antibiotics.

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⌬p19 mutation

A mutation in Campylobacter jejuni that affects iron uptake and contributes to antibiotic resistance.

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Minimum Inhibitory Concentration (MIC)

The minimum concentration of an antibiotic that inhibits bacterial growth.

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Antibiotic tolerance

The ability of a bacterial strain to grow in the presence of an antibiotic.

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Iron supplementation

The process of adding iron to the growth medium to study its effect on bacterial growth and antibiotic sensitivity.

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Mutant strain

A strain of bacteria that has been genetically modified to lack a specific gene.

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Growth and biofilm formation in extracts

The study of how bacteria grow and form biofilms in different environments, specifically in the case of Campylobacter jejuni within human and chicken guts.

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Aerobic growth conditions

Bacteria, such as Campylobacter jejuni, are grown in a controlled environment with specific temperature and shaking speed to encourage their growth.

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Luria-Bertani (LB) broth

A type of culture media used to grow bacteria. It is rich in nutrients and often contains antibiotics to select for specific bacteria.

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Dilution plating

A method to measure the amount of bacteria in a sample by diluting it and counting the number of colonies that grow on a plate.

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Liquid growth cultures

An experiment where bacteria are grown in a liquid medium and the number of bacteria is measured at different time points.

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Biofilm

A thin layer of bacteria that grows on a surface, like a petri dish or a human cell.

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RNA preparation

The study of how bacteria express their genes in different environments.

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Human fecal and chicken cecal extracts

A controlled environment that mimics the conditions found in the human or chicken gut.

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PEB3

The major antigenic peptide PEB3 is involved in adherence to the host, essential for colonization.

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Glutamate Synthase

Glutamate synthase is a key enzyme in nitrogen metabolism, converting ammonia into glutamate.

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C4-dicarboxylate ABC Transporter

C4-dicarboxylate ABC transporter is a membrane protein responsible for importing dicarboxylic acid substrates.

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Di/tripeptide Transporter

Di/tripeptide transporter facilitates the uptake of small peptides, providing amino acids.

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Amino Acid Carrier Protein

Amino acid carrier protein is involved in the transport of amino acids across the membrane.

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Sodium:alanine Symporter

Sodium:alanine symporter co-transports sodium and alanine into the cell, providing energy and amino acid.

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Fumarate Reductase

Fumarate reductase is an enzyme involved in anaerobic respiration, using fumarate as an electron acceptor.

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Methyl-accepting Chemotaxis Protein (MCP)

Methyl-accepting chemotaxis protein (MCP) is a sensor for chemotaxis, guiding the bacteria towards attractants.

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Hemerythrin

Hemerythrin is an oxygen-binding protein that helps the bacteria survive in oxygen-rich environments.

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Thioredoxin Family Protein

Thioredoxin family protein is involved in reducing oxidative stress, protecting the bacteria from damage.

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What is the function of AspA?

Aspartate ammonia-lyase is an enzyme that catalyzes the conversion of aspartate to fumarate and ammonia. It is involved in the metabolism of aspartate, an amino acid.

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Explain the function of the DcuA transporter protein.

The DcuA transporter protein is a membrane protein responsible for transporting C4-dicarboxylates across the cell membrane. It plays a role in anaerobic metabolism, specifically in the transport of succinate and fumarate.

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What does the DcuB protein do?

The DcuB transporter protein is another membrane protein involved in anaerobic metabolism. It works similarly to DcuA, transporting C4-dicarboxylates, contributing to energy production in oxygen-deprived environments.

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What is the role of iron permease?

Iron permease (FTR1 family) proteins are responsible for transporting iron into the cell. This process is crucial for cellular function, as iron is necessary for many enzymes and proteins.

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What is the function of the periplasmic iron-binding protein (p19)?

The periplasmic iron-binding protein (p19) is involved in the transport of iron across the cell membrane. It binds iron ions in the periplasm, the space between the inner and outer membranes of bacteria.

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What is the role of cytochrome C?

Cytochrome c is a heme protein involved in electron transport, a vital process for energy production. It facilitates the transfer of electrons in the electron transport chain.

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What does the CJJ81176_0438 gene code for?

The gene CJJ81176_0438 encodes a putative oxidoreductase subunit protein. Oxidoreductases are enzymes that catalyze oxidation-reduction reactions, which are essential for various cellular processes.

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What are ABC transporters?

ABC transporters are a large family of proteins involved in the transport of various molecules across cell membranes. They use energy to transport molecules against their concentration gradient.

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Why is there an upregulation of iron uptake genes in cells?

The upregulation of genes associated with iron uptake, such as those encoding iron permease, periplasmic iron-binding protein, and ABC transporters, suggests an increased demand for iron in the bacteria.

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What does the upregulation of genes related to metabolism, nutrient uptake, and energy production indicate?

The increase in expression of genes involved in metabolism, nutrient uptake, and energy production indicates that the bacteria are actively growing and utilizing the available resources.

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Dipartite iron uptake system

A type of iron uptake system found in some bacteria, like uropathogenic Escherichia coli, that involves two components. It's essential for the bacteria to scavenge iron from the environment.

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Actinobacillus succinogenes sp. nov.

A bacterial genus known for its role in producing succinic acid, a key metabolite in the bovine rumen. It's a novel strain identified from the digestive system of cattle.

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Hyperosmotic stress response

A type of stress response mechanism found in bacteria, specifically Campylobacter jejuni. It helps the bacterium adapt to changes in environmental conditions, like varying oxygen levels. It's key for their survival in different host environments.

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Campylobacter lanienae

A specific species of bacteria, Campylobacter lanienae, that has been recently identified as a cause of enteritis in humans. This species is relatively new in terms of known human infections.

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Bacterial methionine biosynthesis

A complex process carried out by bacteria like Campylobacter jejuni, involved in producing the amino acid methionine. This process is essential for their growth and survival.

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Frischella perrara

A bacterial genus, Frischella perrara, found in the gut of honeybees. It has been newly discovered and characterized as a distinct species within the Gammaproteobacteria group of bacteria.

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Aspartase (AspA)

A specific protein, AspA, that plays a crucial role in the growth of Campylobacter jejuni, especially under conditions with limited oxygen. This protein is involved in breaking down aspartic acid, an amino acid vital for bacterial metabolism.

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Study Notes

Campylobacter jejuni Transcriptional Response

  • Campylobacter jejuni is a pathogenic bacterium causing gastroenteritis in humans. It's a common commensal in animals, particularly poultry.
  • RNA sequencing was used to study C. jejuni's response to human and chicken intestinal extracts.
  • C. jejuni's transcription was altered in response to extracts compared to medium alone. Key changes related to iron uptake, metabolism, chemotaxis, energy production & osmotic stress.
  • Exposure to human extracts resulted in higher expression of genes involved in respiration (fdhTU) and iron uptake systems (cfbpA, ceuB, chuC, 1649-1655).
  • Genes 1649-1656 and downstream overlapping gene 1656, show these genes are involved in iron scavenging and stress response in the human intestine.
  • Homologues of the 1649-1656 system are found in various bacterial species (including 21 associated with human disease).

Iron Uptake System

  • Genes 1649 and 1650 (p19) encode an iron transporter and a periplasmic iron binding protein, respectively.
  • The 1651-1656 gene cluster is involved in C. jejuni’s iron scavenging.
  • A Δ1651-1656 deletion strain has an iron-sensitive phenotype and reduced growth in acidic environments.
  • This cluster is vital for optimal growth in iron-restricted environments, utilising human fecal extracts as iron sources.

Host Intestinal Extracts

  • Human fecal extracts contain higher total iron content compared to chicken cecal extracts.
  • C. jejuni's response to human fecal extracts involved higher expression of iron uptake-related genes and formate dehydrogenase genes compared to chicken extracts.

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Investigating Campylobacter jejuni Transcriptional Response to Host Intestinal Extracts - PDF

Description

Explore the transcriptional response of Campylobacter jejuni to human and chicken intestinal extracts. This quiz covers key changes in gene expression related to iron uptake, metabolism, and stress responses as revealed through RNA sequencing. Test your knowledge of the mechanisms that enable this pathogen to thrive in diverse environments.

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