This finding sheds light on why Bacillus anthracis does not grow in soil, even though in many ways it resembles a soil-growing bacterium. It has the ability to lie dormant in soil for, in some cases, hundreds of years and then to cause a rapid, often fatal, illness when ingested by a suitable animal host. Bioterrorists have exploited this ability to deadly effect.
Dr. Anil Wipat, Professor Colin Harwood and colleagues at the North East Regional e-Science Centre in Newcastle revealed the new insights after developing a method for deducing and characterising the proteins a bacterium secretes simply from a knowledge of its genome sequence.
Secreted proteins equip a bacterium to survive in its environment and so reveal much about its lifestyle. A soil-living bacterium, for example, secretes proteins that enable it to take up nutrients from the soil. A disease-causing bacterium may secrete proteins that subvert the host’s immune system, enabling the bacterium to infect cells or survive in the bloodstream. Knowledge of a pathogenic bacterium’s secreted proteins and how they function can therefore help with the search for treatments.
As genes carry the code for proteins, researchers are able to use knowledge of a bacterium’s genes to deduce all the proteins it produces. Difficulty arises when trying to pick out only the proteins that are secreted. Methods exist to do this, but are very time-consuming, given that many bacteria secrete 4000 or more proteins. Now, however, the Newcastle researchers have developed an automatic method which makes the identification, analysis and comparison of bacterial secreted proteins from many organisms a realistic proposition.
Based on Taverna workflow technology, which was developed under myGrid, an e-Science project funded by the Engineering and Physical Sciences Research Council (EPSRC), it performs a series of analyses on all the proteins produced by a bacterium to create, by a process of selection and elimination, a list of secreted proteins and their properties. The results are stored in a database. Before this new method, researchers would have had to perform these operations manually, often retrieving algorithms for performing the analyses from separate, distributed computers.
The team decided to test their method on 12 members of the Bacillus family. Family members exhibit a variety of behaviours ranging from the friendly Bacillus subtilis, which lives in the soil, promotes plant growth and is used to produce industrial enzymes and vitamins, to the deadly Bacillus anthracis, which causes anthrax. The full complement of proteins produced by the Bacillus family was fed into the workflow. The number of secreted proteins predicted for each member ranged between 350 and 500.
The secreted proteins were then put through a second workflow which placed them into groups of proteins with similar functions. Of particular interest were groups containing proteins secreted only by pathogenic members and only by non-pathogenic members. Secreted proteins unique to the non-pathogenic bacteria have functions that enable them to live in their habitats, whereas almost all of those unique to the pathogenic family members were of unknown function.
The predicted secreted proteins from Bacillus anthracis help to explain its inability to grow in soil. “When we looked at the secreted proteins, we found that they’re not adapted to utilise molecules in the soil,” says Professor Harwood. However, they do enable Bacillus anthracis to grow in an animal host. Some breakdown animal protein such as muscle fibres, others are the toxins which eventually kill the host, but others belong to the group of proteins of unknown function unique to pathogenic bacteria. “We don’t know what these latter proteins do but we think they help the organism to evade the immune response,” says Professor Harwood. “We’re beginning to understand why Bacillus anthracis behaves in the way that it does –and how it has adapted only to grow in the host and not in the soil,” he adds.
The team is setting up a website to guide users through the process for any bacterium whose genome is known. By identifying the secreted proteins it will be possible to determine some of the previously unsuspected properties of a bacterium, including whether it is likely to be pathogenic or not. The method is also showing promise of commercial application as many enzymes sold commercially, such as plant-derived enzymes used for biofuel production, are proteins harvested from bacteria which secrete them naturally.
Julia Short | alfa
Kakao in Monokultur verträgt Trockenheit besser als Kakao in Mischsystemen
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Ultrasound sensors make forage harvesters more reliable
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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