Mutant genes can promote genetic transfer across taxonomic kingdoms


Date:
June 17, 2021
Source:
Hiroshima University
Summary:
Researchers now have a better understanding of the mechanism
underlying how certain bacteria can transfer genetic material across
taxonomic kingdoms, including to fungi and protists. Their work
could have applications in changing how bacteria perform certain
functions or react to changes in their environment.



FULL STORY ========================================================================== Researchers now have a better understanding of the mechanism underlying
how certain bacteria can transfer genetic material across taxonomic
kingdoms, including to fungi and protists. Their work could have
applications in changing how bacteria perform certain functions or react
to changes in their environment.


========================================================================== Bacteria do not sexually reproduce, but that does not stop them from
exchanging genetic information as it evolves and adapts. During conjugal transfer, a bacterium can connect to another bacterium to pass along
DNA and proteins.

Escherichia coli bacteria, commonly called E. coli, can transfer at
least one of these gene-containing plasmids to organisms across taxonomic kingdoms, including to fungi and protists. Now, researchers from Hiroshima University have a better understanding of this genetic hat trick, which
has potential applications as a tool to promote desired characteristics
or suppress harmful ones across genetic hosts.

They published their results on May 20 in Frontiers in Microbiology.

Plasmids transfer from one bacterium -- the donor -- to another -- the recipient. A particular kind of plasmid, called IncP1, can be hosted
by a variety of bacteria and, seemingly as a result of its broad hosts,
can transfer DNA to recipients beyond bacteria. The hypothesis is that
the plasmid contains genes cultivated from different hosts and donors, resulting in this unique ability.

"Although conjugation factors encoded on plasmids have been extensively analyzed, those on the donor chromosome have not," said paper author
Kazuki Moriguchi, associate professor, Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University.

There have been some studies on the various genes, according to Moriguchi,
but the function of the genes was not examined, so it is not clear how
they were related to the conjugation mechanism.

In this study, the researchers conducted a genome-wide survey on an
extensive collection of bacteria mutants as donors to yeast. The mutants
were engineered to have specific genes "knocked out" in order to study
how the overall system performs without the presence of that specific
gene, allowing researchers to infer information about the gene's function.

"We focused on 'up' mutants that have the ability to accelerate
conjugative transfer to both prokaryotes and eukaryotes as they could be
potent donor strains applicable to gene introduction tools," Moriguchi
said, noting how IncP1's ability to transmit genetic material across
kingdoms could be used to develop precise tools to introduce genes
capable of changing how the bacteria perform certain functions or react
to changes in their environments.

Out of 3,884 mutants surveyed, three were identified that could conjugate across E. coli or from E. coli to yeast without accumulating genetic
material, indicating that the genes worked together. The researchers
analyzed the genes but were unable to elucidate the exact target
or targets of conjugation mechanism that allows for cross-kingdom
transfer. However, their analysis did reveal how the genes appear to work.

Two of the genes work to repress the unknown target in the E. coli donor.

Simultaneously, the third gene is inactivated, allowing another unknown
target to resume activity.

"The results suggest that the unknown target factors of these three
genes form a complex in order to activate or repress the conjugation,
either directly or indirectly at an identical step or steps of the
IncP1 conjugation machinery, although the exact mechanism beyond this phenomenon remains unknown," Moriguchi said.

According to Moriguchi, the data collected in this study can help
facilitate the breeding of donor strains from various bacteria, each
of which carries a high affinity with target organisms in addition to
having a high conjugation ability.

========================================================================== Story Source: Materials provided by Hiroshima_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Fatin Iffah Rasyiqah Mohamad Zoolkefli, Kazuki Moriguchi,
Yunjae Cho,
Kazuya Kiyokawa, Shinji Yamamoto, Katsunori Suzuki. Isolation and
Analysis of Donor Chromosomal Genes Whose Deficiency Is Responsible
for Accelerating Bacterial and Trans-Kingdom Conjugations by IncP1
T4SS Machinery. Frontiers in Microbiology, 2021; 12 DOI: 10.3389/
fmicb.2021.620535 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/06/210617101247.htm

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