Back to Shapiro: an editing bacterium (Evolution)

by David Turell , Monday, September 19, 2022, 20:06 (585 days ago) @ David Turell

Another fit to Shapiro, Klebsiella:

https://phys.org/news/2022-09-silent-mutations-bacteria-evade-antibiotics.html

"Researchers have discovered a new way hospital-acquired infections resist antibiotics, through a "silent" genetic mutation.

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"The researchers looked at the bacterium Klebsiella pneumoniae, which causes infections in the lungs, blood and wounds of those in hospitals, with patients that have compromised immune systems, such as those in intensive care units, being especially vulnerable.

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"In order to be effective, antibiotics need to get inside bacteria, and in K. pneumoniae this happens via a channel in the bacterium's outer membrane, formed by a protein called OmpK36. The team discovered a genetic mutation that makes the bacteria produce less of the protein, effectively shutting some of these channels and keeping carbapenem antibiotics out.

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"This mutation, however, works differently to standard mutations that result in antibiotic resistance. Usually, mutations change the genetic code so that when it is "read" by ribosomes and converted into a protein, it produces a different chain of amino acids with different functions.

"This mutation still produces the same amino acid chain, but alters the structure of an important mRNA intermediate, preventing ribosomes reading the code and producing protein from it.

"When looking for mutations, genomic techniques are usually searching for changes to the amino acid sequence. However, since this mutation alters a structure, rather than the sequence itself, it could be thought of as a "silent" mutation.

"First author Dr. Joshua Wong, from the Department of Life Sciences at Imperial, said, "In the age of big data and genomics, mutations such as we have discovered may be considered 'silent' as the genetic code results in the same protein sequence.

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"Using data from resistant bacteria samples collected globally, the team showed that the mutation had arisen several times independently. This suggests it is not random, and is instead driven by the need of the bacteria to defend itself again the antibiotics.

"Lead researcher Professor Gad Frankel, from the Department of Life Sciences at Imperial, said, "The mutation evolved on several occasions independently, and this tells us that this novel mechanism is not a one-off fluke, but instead driven by antibiotic consumption. This suggests that the mutation occurs under antibiotic pressure and highlights the side effects of excessive antibiotic usage in hospitals and other settings.'"

Comment: fits Shapiro to a 'T'. DNA had to be edited to have this happen. This is a minor modification of a protein pathway, not speciation as dhw would hope for in his extrapolated theorizing.