Nav: Home

Chlamydia: How bacteria take over control

March 28, 2017

When Chlamydia trachomatis infects a human cell, it faces a huge challenge: It must prevent the cell from triggering programmed cell death to prevent the bacteria from replicating and spreading throughout the body. Since numerous metabolic processes are either missing or fragmented in the pathogen, it is reliant on the host cell to supply the vital nutrients on a permanent basis.

Research projects worldwide focus on how the bacteria manage to keep the cell alive and working for it. Scientists from the University of Würzburg have now uncovered a new detail of these processes. They identified a mechanism with which Chlamydia trachomatis influences the mitochondria, the cells' power plants, thereby preventing the cells from committing suicide. In the scientific journal Journal of Cell Biology, the scientists present the results of their work.

The role of mitochondria

The study was led by Professor Thomas Rudel, who holds the Chair of Microbiology at the University of Würzburg. Already three years ago, Rudel and his team showed that chlamydiae disable the tumour suppressor protein p53 in infected cells and initiate a process which repairs DNA damages resulting from chlamydia infection. By blocking p53, the bacteria prevent the cell from knocking itself out in the worst case, thereby winning time for replication.

In their new study, the microbiologists took a closer look at the mitochondria. "Mitochondria play a crucial role in energy supply and programmed cell death," Thomas Rudel explains. He sees strong evidence that changes in their architecture and dynamics are closely related to the cells' general metabolic processes.

Focus on small RNA molecules

What impact does a chlamydia infection have on mitochondria? To answer this question, Rudel's team scrutinized another actor in the goings-on inside cells: the so-called miRNAs or microRNAs. These small RNA molecules control vital processes inside cells by regulating complex networks of genes.

High-throughput sequencing allowed Rudel and his team to study in depth how a chlamydia infection impacts the miRNA expression of the infected cell. The most striking finding is a greatly increased production of the miR-30c-5p microRNA. A high concentration of these tiny RNA molecules is beneficial for the bacteria: "They cause the tumour suppressor protein to be downregulated permanently," Thomas Rudel explains.

In return, blocking miR-30c causes the chlamydia trouble, because the cell increases its production of Drp1, a protein that fragments the mitochondria in cells under stress. As its concentration inside cells increases, so does the stress-related mitochondrial division rate while the infected cell's chances of surviving the bacterial attack improve. This is because chlamydial growth is inhibited significantly by the fragmented mitochondria that supply less energy and starve the pathogens.

Chlamydia: Resourceful invaders

Bacteria of the strain Chlamydia trachomatis are responsible for a number of serious diseases in humans. Chlamydia infections are the most frequent sexually transmitted diseases worldwide. Up to ten percent of the population worldwide are estimated to be infected with the bacteria depending on the age group.

Untreated, chlamydia infection can cause fallopian tubes blockage in women which can result in tubal pregnancy or infertility. Newer findings even suggest that chlamydia infections promote ovarian cancer. Men can become infertile after an infection.

Another consequence of chlamydia infection occurs especially in tropical countries: The bacteria infect the eyes and may cause blindness. It is estimated that around 150 million people are affected by the disease. Other strains may trigger pneumonia and are suspected to cause arteriosclerosis and Alzheimer's.
-end-
Chlamydia preserves the mitochondrial network necessary for replication via microRNA-dependent inhibition of fission. Suvagata Roy Chowdhury, Anastasija Reimer, Malvika Sharan, Vera Kozjak Pavlovic, Ana Eulalio, Bhupesh K. Prusty, Martin Fraunholz, Karthika Karunakaran, and Thomas Rudel The Journal or Cell Biology. https://doi.org/10.1083/jcb.201608063

University of Würzburg

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

The Bacteria Book: The Big World of Really Tiny Microbes
by Steve Mould (Author)

Bacteria: Staph, Strep, Clostridium, and Other Bacteria (Class of Their Own (Paperback))
by Judy Wearing (Author)

A Field Guide to Bacteria (Comstock Book)
by Betsey Dexter Dyer (Author)

Bacteria: A Very Short Introduction (Very Short Introductions)
by Sebastian G.B. Amyes (Author)

The Surprising World of Bacteria with Max Axiom, Super Scientist (Graphic Science)
by Agnieszka Biskup (Author), Anne Timmons (Author), Matt Webb (Author), Krista Ward (Author)

I Contain Multitudes: The Microbes Within Us and a Grander View of Life
by Ed Yong (Author)

Superbugs: An Arms Race against Bacteria
by William Hall (Author), Anthony McDonnell (Author), Jim O'Neill Chair of a formal Review on Antimicrobial Resistance (AMR) (Author)

From Bacteria to Bach and Back: The Evolution of Minds
by W. W. Norton & Company

Are All Bacteria Dangerous? Biology Book for Kids | Children's Biology Books
by Baby Professor (Author)

Premed Kids: Microbiology - Bacteria & Viruses
by April Chloe Terrazas (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Where Joy Hides
When we focus so much on achievement and success, it's easy to lose sight of joy. This hour, TED speakers search for joy in unexpected places, and explain why it's crucial to a fulfilling life. Speakers include inventor Simone Giertz, designer Ingrid Fetell Lee, journalist David Baron, and musician Meklit Hadero.
Now Playing: Science for the People

#500 500th Episode
This week we turn 500! To celebrate, we're taking the opportunity to go off format, talk about the journey through 500 episodes, and answer questions from our lovely listeners. Join hosts Bethany Brookshire and Rachelle Saunders as we talk through the show's history, how we've grown and changed, and what we love about the Science for the People. Here's to 500 more episodes!