New route of acquiring antibiotic resistance in bacteria is the most potent one to date

October 11, 2018, National University of Singapore
**New route of acquiring antibiotic resistance in bacteria is the most potent one to date
The induced prophage genome (blue) replicates in situ bidirectionally (1) and amplifies the adjacent bacterial DNA (gray). Phage terminase initiates in situ DNA packaging from a pac site (2), while prophage excision occurs (3) in parallel. Prophage excision produces infectious phage particles. Lateral-transducing particles are completed (4) when a headful capacity is reached. The DNA packaging machinery then proceeds to fill additional headfuls of bacterial chromosome for several hundred kilobases. Credit: Chen J, Quiles-Puchalt N, Chiang YN, et al. Genome hypermobility by lateral transduction. Science. 2018. [In Press]

Bacteriophages (or phages) are viruses that infect and parasitize bacteria. These phages can transfer DNA from one bacterium to another through a process known as genetic transduction. This is thought to be the major means by which bacteria evolve and acquire the antibiotic resistance and virulence factors that accelerate the emergence of new and progressively more pathogenic strains. Up to now, two mechanisms of genetic transduction were known: generalized and specialized transduction. For over 60 years, since their discovery by American scientist and Nobel laureate Joshua Lederberg, these two mechanisms have stood as the only mechanisms of genetic transduction.

In a paper published online in the journal Science on October 12, 2018, research teams led by NUS Medicine and the University of Glasgow report the discovery of a third mode of transduction. Termed lateral transduction, this new mode appears to be the most powerful means of transduction yet discovered, with the ability to transfer large sections of bacterial chromosomes (several hundred kilobases) between bacteria at extremely high frequencies.

When a infects a bacterial cell, it normally reproduces in one of two ways: (1) the lytic cycle, in which the phage reproduces and lyses the cell, resulting in the release of new phage particles; or (2) the lysogenic cycle, in which the phage DNA incorporates into the and replicates together with the . In (2), certain stimuli can provoke the phage DNA to cut itself out of the host genome (excision), assemble with proteins into new phage particles (packaging), undergo maturation and lyse the host cells. The released phages from both (1) and (2) can then infect other bacteria and transfer their DNA, which includes DNA from the host cell.

In contrast, the researchers, led by Assistant Professor John Chen of NUS Medicine, found that lateral transduction occurs when phages delay excision to late in their life cycle. Instead, the phages initiate DNA replication while they are still part of the host genome, resulting in multiple integrated phage genomes. DNA packaging can then initiate on some genomes, resulting in the packaging and transfer of chromosomal DNA to other bacteria, while other phage genomes excise and lead to normal phage maturation.

Assistant Professor Chen says, "Lateral transduction elevates the concept of mobile genetic elements well beyond that of defined DNA elements, by transforming sections of the genome into hypermobile platforms that are capable of transferring any genetic element within their boundaries at incredibly high frequencies."

The discovery of this highly efficient mode of gene transfer could help to explain the rapid evolution of that occurs, for example, in the development of multi-drug resistant strains.

Putting the discovery in context, Assistant Professor Chen observed that "phages are by far the most abundant biological entities on the planet, and the importance of genetic transduction as one of the principal drivers of microbial evolution has never been more apparent than with the discovery of lateral ."

Explore further: CRISPR-Cas9 may be a double-edged sword for bacteria

More information: J. Chen el al., "Genome hypermobility by lateral transduction," Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aat5867

"A common trick for transferring bacterial DNA," Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aav1723

Related Stories

CRISPR-Cas9 may be a double-edged sword for bacteria

February 15, 2018

A team of researchers with the Catholic University of America has found evidence that suggests a defense mechanism used by bacteria to ward off phage attacks might also be benefiting the phages. In their paper published on ...

Viruses that infect bacteria abound in bladder

January 29, 2018

Phages—viruses that infect bacteria—are abundant in the bacteria that inhabit the female bladder. This is good news, because phage could be used as alternative treatment when antibiotics become resistant to pathogenic ...

Phage spread antibiotic resistance

May 15, 2015

Investigators found that nearly half of the 50 chicken meat samples purchased from supermarkets, street markets, and butchers in Austria contained viruses that are capable of transferring antibiotic resistance genes from ...

Phages found to use peptide to communicate with one another

January 19, 2017

(Phys.org)—A team of researchers from several institutions in Israel has, for the first time, identified a molecule that phages use to communicate with one another. In their paper published in the journal Nature, the team ...

Phages work together to suppress CRISPR bacterial immunity

July 19, 2018

CRISPR, or clustered regularly interspaced short palindromic repeats, are an essential part of bacterial immunity designed to defend against foreign DNA. In bacteria, CRISPR acts just like it does in human cells as a pair ...

Recommended for you

How plants bind their green pigment chlorophyll

October 19, 2018

Chlorophyll is the pigment used by all plants for photosynthesis. There are two versions, chlorophyll a and chlorophyll b. These are structurally very similar to one another but have different colors, blue-green and yellowish ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.