New mechanisms of 'social networking' in bacteria

Bacillus subtilis
The Bacterium Bacillus subtilis taken with a Tecnai T-12 TEM. Taken by Allon Weiner, The Weizmann Institute of Science, Rehovot, Israel. 2006. Credit: Public Domain

Bacteria have traditionally been viewed as solitary organisms that "hang out on their own," says molecular biologist Kevin Griffith of the University of Massachusetts Amherst. However, scientists now realize that in fact, bacteria exhibit social behavior within groups.

As he explains, "Individual bacteria within a population communicate with members of the group through a process called quorum sensing, where chemical signals and extracellular peptides serve as the language for bacterial communication." It is not just "social" networking, he adds. Bacterial communities use to control a variety of biomedically relevant .

In a new paper in a recent early online edition of Molecular Microbiology, he and co-authors Kristina Boguslawski and Patrick Hill describe how they deciphered this bacterial communication to reveal new mechanisms of regulating in the model bacterium Bacillus subtilis.

"Research in my lab is devoted to deciphering these different bacterial languages, understanding how bacteria perceive these signals, and determining how bacteria use this information to regulate biological processes at the molecular level," says Griffith. "In this paper, we have expanded the range of biological processes known to be controlled by a plasmid-encoded quorum response pair known as Rap60-Phr60.

Using biochemical approaches, the authors found that Rap60 regulates the activity of two important transcription factors by "mechanisms never before observed for Rap proteins," says Griffith. "This work changes the way we think about these important regulatory proteins. The implications likely extend beyond Bacillus biology as they represent potential novel targets for the development of antibiotic and therapeutics in ."

In addition to providing fundamental knowledge about how this regulation occurs in a non-pathogenic bacterium like B. subtilis, understanding these pathways has the potential to provide new insight into how pathogenic bacteria regulate virulence factors and colonize hosts, which can have a profound impact on human health, he adds.

He explains, "Bacteria within a population secrete extracellular signals that provide the cue to coordinate biological processes as a group. Many pathogenic bacteria use these extracellular signals to regulate the production of antibiotics and , the timing of which is important in disease."

Each species of bacteria has its own unique language, the authors say. In addition, there are "universal signals, analogous to Morse code, used for communication between different species of bacteria," says Griffith. "In microbial communities, within a similar group communicate with one another, while other groups are eavesdropping or even disrupting the others' communication. It is biological espionage. Bacteria that can communicate with one another and work together as a group will be more successful in competing for resources than individuals."

The researchers found, in addition to controlling the production of degradative enzymes, which was already known, that the Rap60 protein inhibits sporulation, genetic competence (the uptake of foreign DNA), and biofilm formation. Phr60 acts as an extracellular cell-cell signaling peptide that coordinates the activity of Rap60 with population density, says Griffith.

In the future, he adds, "We are currently looking at the role Rap60 and other Rap proteins play in regulating gene expression under a variety of different growth conditions. It is becoming increasingly clear that Rap proteins are more versatile than we originally believed in terms of the number of pathways they control and the range of different mechanisms used to regulate gene expression. In addition, we are expanding our investigations to better understand inter-species signaling between B. subtilis and other bacterial and eukaryotic microbes that have biomedical importance."


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Bacteria coordinate activities with chemical 'language'

More information: Novel mechanisms of controlling the activities of the transcription factors Spo0A and ComA by the plasmid-encoded quorum sensing regulators Rap60-Phr60 in Bacillus subtilis, Molecular Microbiology, DOI: 10.1111/mmi.12939
Journal information: Molecular Microbiology

Citation: New mechanisms of 'social networking' in bacteria (2015, April 7) retrieved 17 June 2019 from https://phys.org/news/2015-04-mechanisms-social-networking-bacteria.html
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JVK
Apr 08, 2015
"...the Rap60 protein inhibits sporulation, genetic competence (the uptake of foreign DNA), and biofilm formation. Phr60 acts as an extracellular cell-cell signaling peptide that coordinates the activity of Rap60 with population density..."

See also: http://www.ncbi.n...24693349 Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors.

"Among different bacterial species existing in similar environments, DNA uptake (Palchevskiy & Finkel, 2009) appears to have epigenetically 'fed' interspecies methylation and speciation via conjugation (Fall et al., 2007; Finkel & Kolter, 2001; Friso & Choi, 2002). This indicates that reproduction began with an active nutrient uptake mechanism in heterospecifics and that the mechanism evolved to become symbiogenesis in the conspecifics of asexual organisms (Margulis, 1998). In yeasts, epigenetic changes driven by nutrition might then have led to..." cont.

JVK
Apr 08, 2015
cont.
"... the creation of novel cell types, which are required at evolutionary advent of sexual reproduction (Jin et al., 2011). These epigenetic changes probably occur across the evolutionary continuum that includes both nutrition-dependent reproduction in unicellular organisms and sexual reproduction in mammals. For example, ingested plant microRNAs influence gene expression across kingdoms (Zhang et al., 2012). In mammals, this epigenetically links what mammals eat to changes in gene expression (McNulty et al., 2011) and to new genes required for the evolutionary development of the mammalian placenta (Lynch, Leclerc, May, & Wagner, 2011) and the human brain..."

See also: Nutrient-dependent/pheromone-controlled adaptive evolution: a model http://www.ncbi.n...3960071/ "...this model can be compared to any other factual representations of epigenesis and epistasis for determination of the best scientific 'fit'."

JVK
Apr 08, 2015
See also:
Bacteria coordinate activities with chemical 'language' http://phys.org/n...tml#nRlv

Signaling receptor may provide a target for reducing virulence without antibiotics http://phys.org/n...tml#nRlv

New methods to visualize bacterial cell-to-cell communication http://phys.org/n...tml#nRlv

Researchers report on CRISPR-cas surveillance complex that targets RNA http://phys.org/n...tml#nRlv

Excerpt: "...bacteria themselves must confront a relentless tide of deadly invaders that include viruses and snippets of nucleic acid known as plasmids. To protect themselves, bacteria have evolved their own immune system. This system is adaptive and nucleic acid-based. It revolves around complexes..."

Ecological adaptation revolves around conserved molecular mechanisms of RNA-mediated events.

JVK
Apr 10, 2015
Re: Ecological adaptation revolves around conserved molecular mechanisms of RNA-mediated events.

See also: Delicate magnolia scent activates human pheromone receptor
http://medicalxpr...one.html

In Kohl (2013) I wrote: ingested plant microRNAs influence gene expression across kingdoms (Zhang et al., 2012). In mammals, this epigenetically links what mammals eat to changes in gene expression (McNulty et al., 2011) and to new genes required for the evolutionary development of the mammalian placenta (Lynch, Leclerc, May, & Wagner, 2011) and the human brain..."

Wallrabenstein et al (2015) link nutrient-dependent changes in the microRNA/messenger RNA (mRNA) balance to human communication with pheromones.

"3.1. mRNA of all intact VN1Rs is present in human olfactory mucosa"
See: 3.2. "Genetic variations of chemoreceptors caused by single nucleotide polymorphisms (SNPs) that result in an amino acid change..."

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