1
|
Belcher LJ, Dewar AE, Hao C, Katz Z, Ghoul M, West SA. SOCfinder: a genomic tool for identifying social genes in bacteria. Microb Genom 2023; 9:001171. [PMID: 38117204 PMCID: PMC10763506 DOI: 10.1099/mgen.0.001171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/08/2023] [Indexed: 12/21/2023] Open
Abstract
Bacteria cooperate by working collaboratively to defend their colonies, share nutrients, and resist antibiotics. Nevertheless, our understanding of these remarkable behaviours primarily comes from studying a few well-characterized species. Consequently, there is a significant gap in our understanding of microbial social traits, particularly in natural environments. To address this gap, we can use bioinformatic tools to identify genes that control cooperative or otherwise social traits. Existing tools address this challenge through two approaches. One approach is to identify genes that encode extracellular proteins, which can provide benefits to neighbouring cells. An alternative approach is to predict gene function using annotation tools. However, these tools have several limitations. Not all extracellular proteins are cooperative, and not all cooperative behaviours are controlled by extracellular proteins. Furthermore, existing functional annotation methods frequently miss known cooperative genes. We introduce SOCfinder as a new tool to find bacterial genes that control cooperative or otherwise social traits. SOCfinder combines information from several methods, considering if a gene is likely to [1] code for an extracellular protein [2], have a cooperative functional annotation, or [3] be part of the biosynthesis of a cooperative secondary metabolite. We use data on two extensively-studied species (P. aeruginosa and B. subtilis) to show that SOCfinder is better at finding known cooperative genes than existing tools. We also use theory from population genetics to identify a signature of kin selection in SOCfinder cooperative genes, which is lacking in genes identified by existing tools. SOCfinder opens up a number of exciting directions for future research, and is available to download from https://github.com/lauriebelch/SOCfinder.
Collapse
Affiliation(s)
| | - Anna E. Dewar
- Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
| | - Chunhui Hao
- Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
| | - Zohar Katz
- Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
| | - Melanie Ghoul
- Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
| | - Stuart A. West
- Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
| |
Collapse
|
2
|
Lerch BA, Smith DA, Koffel T, Bagby SC, Abbott KC. How public can public goods be? Environmental context shapes the evolutionary ecology of partially private goods. PLoS Comput Biol 2022; 18:e1010666. [PMID: 36318525 PMCID: PMC9651594 DOI: 10.1371/journal.pcbi.1010666] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 11/11/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
The production of costly public goods (as distinct from metabolic byproducts) has largely been understood through the realization that spatial structure can minimize losses to non-producing “cheaters” by allowing for the positive assortment of producers. In well-mixed systems, where positive assortment is not possible, the stable production of public goods has been proposed to depend on lineages that become indispensable as the sole producers of those goods while their neighbors lose production capacity through genome streamlining (the Black Queen Hypothesis). Here, we develop consumer-resource models motivated by nitrogen-fixing, siderophore-producing bacteria that consider the role of colimitation in shaping eco-evolutionary dynamics. Our models demonstrate that in well-mixed environments, single “public goods” can only be ecologically and evolutionarily stable if they are partially privatized (i.e., if producers reserve a portion of the product pool for private use). Colimitation introduces the possibility of subsidy: strains producing a fully public good can exclude non-producing strains so long as the producing strain derives sufficient benefit from the production of a second partially private good. We derive a lower bound for the degree of privatization necessary for production to be advantageous, which depends on external resource concentrations. Highly privatized, low-investment goods, in environments where the good is limiting, are especially likely to be stably produced. Coexistence emerges more rarely in our mechanistic model of the external environment than in past phenomenological approaches. Broadly, we show that the viability of production depends critically on the environmental context (i.e., external resource concentrations), with production of shared resources favored in environments where a partially-privatized resource is scarce. Many organisms produce “public goods”, substances that may directly benefit their competitors as well as themselves. Because goods production is costly, understanding the evolutionary stability of public goods production has been a subject of considerable interest: what keeps cheaters from taking over a population and driving producers to extinction? Here, we ask when partial privatization of public goods (that is, when producers retain some portion of the good for their own exclusive use) is sufficient to stabilize production even in the absence of spatial structure, and how this depends on environmental conditions. We derive lower bounds for the amount of privatization needed to stabilize production and find that these bounds depend critically on environmental conditions. We further investigate the case of two public goods, each needed for the acquisition of the other, and each a resource whose availability limits growth. We find that the ecological dynamics of such colimiting resources can interact, with privatization of one resource subsidizing more-public, or even fully public, production of the other. Finally, we offer the perspective that producers are not “losers” in a race of loss-of-function mutations, but rather can do no better than to produce the resource in a given set of conditions.
Collapse
Affiliation(s)
- Brian A. Lerch
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| | - Derek A. Smith
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Thomas Koffel
- W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, Michigan, United States of America
| | - Sarah C. Bagby
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Karen C. Abbott
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
| |
Collapse
|
3
|
Jautzus T, van Gestel J, Kovács ÁT. Complex extracellular biology drives surface competition during colony expansion in Bacillus subtilis. THE ISME JOURNAL 2022; 16:2320-2328. [PMID: 35790818 PMCID: PMC9477810 DOI: 10.1038/s41396-022-01279-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/13/2022] [Accepted: 06/20/2022] [Indexed: 04/29/2023]
Abstract
Many bacteria grow on surfaces in nature, where they form cell collectives that compete for space. Within these collectives, cells often secrete molecules that benefit surface spreading by, for example, reducing surface tension or promoting filamentous growth. Although we have a detailed understanding of how these molecules are produced, much remains unknown about their role in surface competition. Here we examine sliding motility in Bacillus subtilis and compare how secreted molecules, essential for sliding, affect intraspecific cooperation and competition on a surface. We specifically examine (i) the lipopeptide surfactin, (ii) the hydrophobin protein BslA, and (iii) exopolysaccharides (EPS). We find that these molecules have a distinct effect on surface competition. Whereas surfactin acts like a common good, which is costly to produce and benefits cells throughout the surface, BslA and EPS are cost-free and act locally. Accordingly, surfactin deficient mutants can exploit the wild-type strain in competition for space, while BslA and EPS mutants cannot. Supported by a mathematical model, we show that three factors are important in predicting the outcome of surface competition: the costs of molecule synthesis, the private benefits of molecule production, and the diffusion rate. Our results underscore the intricate extracellular biology that can drive bacterial surface competition.
Collapse
Affiliation(s)
- Theresa Jautzus
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Jordi van Gestel
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Ákos T Kovács
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, 07743, Jena, Germany.
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark.
| |
Collapse
|
4
|
West SA, Cooper GA, Ghoul MB, Griffin AS. Ten recent insights for our understanding of cooperation. Nat Ecol Evol 2021; 5:419-430. [PMID: 33510431 PMCID: PMC7612052 DOI: 10.1038/s41559-020-01384-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 12/11/2020] [Indexed: 01/29/2023]
Abstract
Since Hamilton published his seminal papers in 1964, our understanding of the importance of cooperation for life on Earth has evolved beyond recognition. Early research was focused on altruism in the social insects, where the problem of cooperation was easy to see. In more recent years, research into cooperation has expanded across the entire tree of life, and has been revolutionized by advances in genetic, microbiological and analytical techniques. We highlight ten insights that have arisen from these advances, which have illuminated generalizations across different taxa, making the world simpler to explain. Furthermore, progress in these areas has opened up numerous new problems to solve, suggesting exciting directions for future research.
Collapse
Affiliation(s)
- Stuart A West
- Department of Zoology, University of Oxford, Oxford, UK.
| | - Guy A Cooper
- Department of Zoology, University of Oxford, Oxford, UK
| | | | | |
Collapse
|
5
|
Kramer J, Özkaya Ö, Kümmerli R. Bacterial siderophores in community and host interactions. Nat Rev Microbiol 2020; 18:152-163. [PMID: 31748738 PMCID: PMC7116523 DOI: 10.1038/s41579-019-0284-4] [Citation(s) in RCA: 374] [Impact Index Per Article: 93.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2019] [Indexed: 01/06/2023]
Abstract
Iron is an essential trace element for most organisms. A common way for bacteria to acquire this nutrient is through the secretion of siderophores, which are secondary metabolites that scavenge iron from environmental stocks and deliver it to cells via specific receptors. While there has been tremendous interest in understanding the molecular basis of siderophore synthesis, uptake and regulation, questions about the ecological and evolutionary consequences of siderophore secretion have only recently received increasing attention. In this Review, we outline how eco-evolutionary questions can complement the mechanistic perspective and help to obtain a more integrated view of siderophores. In particular, we explain how secreted diffusible siderophores can affect other community members, leading to cooperative, exploitative and competitive interactions between individuals. These social interactions in turn can spur co-evolutionary arms races between strains and species, lead to ecological dependencies between them and potentially contribute to the formation of stable communities. In brief, this Review shows that siderophores are much more than just iron carriers: they are important mediators of interactions between members of microbial assemblies and the eukaryotic hosts they inhabit.
Collapse
Affiliation(s)
- Jos Kramer
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
| | - Özhan Özkaya
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
6
|
Computational Assessment of Bacterial Protein Structures Indicates a Selection Against Aggregation. Cells 2019; 8:cells8080856. [PMID: 31398930 PMCID: PMC6721704 DOI: 10.3390/cells8080856] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 12/14/2022] Open
Abstract
The aggregation of proteins compromises cell fitness, either because it titrates functional proteins into non-productive inclusions or because it results in the formation of toxic assemblies. Accordingly, computational proteome-wide analyses suggest that prevention of aggregation upon misfolding plays a key role in sequence evolution. Most proteins spend their lifetimes in a folded state; therefore, it is conceivable that, in addition to sequences, protein structures would have also evolved to minimize the risk of aggregation in their natural environments. By exploiting the AGGRESCAN3D structure-based approach to predict the aggregation propensity of >600 Escherichia coli proteins, we show that the structural aggregation propensity of globular proteins is connected with their abundance, length, essentiality, subcellular location and quaternary structure. These data suggest that the avoidance of protein aggregation has contributed to shape the structural properties of proteins in bacterial cells.
Collapse
|
7
|
Bruce JB, West SA, Griffin AS. Functional amyloids promote retention of public goods in bacteria. Proc Biol Sci 2019; 286:20190709. [PMID: 31138071 DOI: 10.1098/rspb.2019.0709] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The growth and virulence of bacteria depends upon a number of factors that are secreted into the environment. These factors can diffuse away from the producing cells, to be either lost or used by cells that do not produce them (cheats). Mechanisms that act to reduce the loss of secreted factors through diffusion are expected to be favoured. One such mechanism may be the production of Fap fibrils, needle-like fibres on the cell surface observed in P. aeruginosa, which can transiently bind several secreted metabolites produced by cells. We test whether Fap fibrils help retain a secreted factor, the iron-scavenging molecule pyoverdine, and hence reduce the potential for exploitation by non-producing, cheating cells. We found that: (i) wild-type cells retain more iron-chelating metabolites than fibril non-producers; (ii) purified Fap fibrils can prevent the loss of the iron-chelators PQS ( Pseudomonas quinolone signal) and pyoverdine; and (iii) pyoverdine non-producers have higher fitness in competition with fibril non-producers than with wild-type cells. Our results suggest that by limiting the loss of a costly public good, Fap fibrils may play an important role in stabilizing cooperative production of secreted factors.
Collapse
Affiliation(s)
- John B Bruce
- Department of Zoology, University of Oxford , Oxford , UK
| | - Stuart A West
- Department of Zoology, University of Oxford , Oxford , UK
| | | |
Collapse
|