The structure of the speargun-like injection systems in two types ofbacteria have been described for the first time by biologists from ETH Zurich. The special machines used by the microbes could one day be used in biomedicine.
Manybacteria have sophisticated injection devices that are used to do amazing things. A bacterium inoculates certain molecule into a worm larva through a machine composed of proteins, which in turn transforms the worm into an adult worm. Otherbacteria use these weapons to kill foreign strains ofbacteria or to defend themselves against scavenger cells.
Two novel injection systems made by blue-green algae have been described by researchers in the group of Martin Pilhofer.
The newly discovered contractile injection systems have a few unique features. They give information about the evolutionary differences between injection system classes.
The CISs work like needles. When the outer sheath module of the nanomachine contracts, a hidden tube is shot out. There are either injected into the environment or directly into the target cell.
The cell has a surprising anchoring.
The researchers found a novel CIS that was attached to the so-called thylakoid membrane, which is where the photosynthesis takes place, but it was not anchored in the cell.
That was the biggest surprise for us according to the lead author of the study. The tCIS fills their purpose despite the unusual location. The outer cell layers detach if the cyanobacteria are stressed by excessive salt concentrations in the water or ultraviolet light. The tCIS is ready to fire upon contact with potential target cells.
According to Weiss, the life cycle of cyanobacteria is an important role in the life cycle of the spear guns. He thinks that the tCIS could play a role in the programmed cell death of individual cells.
Extracellular injection system.
On the other hand, the researchers from the ETH discovered and described a marine bacterium that is not anchored in the cell at all.
The structure of this specific subtype of ejected CIS was determined using high resolution cryo-electron microscopy, which no other working group had previously been able to do.
From molecule to wholebacteria.
This work shows how different techniques can be used to get an idea of how these systems and structures work. There is a need to move from laboratory strains to environmental samples in order to understand the role of injection systems in the life cycle.
Future use of medicine.
The studies help researchers understand how organisms affect the environment. Different sites in these systems shed light on how each CIS is organized for a specific purpose, as well as how different spearguns cause different cellular effects.
It is possible that future researchers will use the modular structure in biomedicine to redesign it so that a speargun can target specific cell types and fire drugs or antimicrobials.
More information: Gregor L. Weiss et al, Structure of a thylakoid-anchored contractile injection system in multicellular cyanobacteria, Nature Microbiology (2022). DOI: 10.1038/s41564-021-01055-yThe structure of an injection system from a marine bacterium has been identified. There is a DOI titled " 10.1038/s41564-022-01059-2".
Journal information: Nature Microbiology Citation: Researchers discover speargun-like molecular injection systems in two types of bacteria (2022, March 3) retrieved 3 March 2022 from https://phys.org/news/2022-03-speargun-like-molecular-bacteria.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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