Predataxis behavior in Myxococcus xanthus

Department of Microbiology, University of Iowa, 51 Newton Road, Iowa City, IA 52242, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 11/2008; 105(44):17127-32. DOI: 10.1073/pnas.0804387105
Source: PubMed


Spatial organization of cells is important for both multicellular development and tactic responses to a changing environment. We find that the social bacterium, Myxococcus xanthus utilizes a chemotaxis (Che)-like pathway to regulate multicellular rippling during predation of other microbial species. Tracking of GFP-labeled cells indicates directed movement of M. xanthus cells during the formation of rippling wave structures. Quantitative analysis of rippling indicates that ripple wavelength is adaptable and dependent on prey cell availability. Methylation of the receptor, FrzCD is required for this adaptation: a frzF methyltransferase mutant is unable to construct ripples, whereas a frzG methylesterase mutant forms numerous, tightly packed ripples. Both the frzF and frzG mutant strains are defective in directing cell movement through prey colonies. These data indicate that the transition to an organized multicellular state during predation in M. xanthus relies on the tactic behavior of individual cells, mediated by a Che-like signal transduction pathway.

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Available from: John R Kirby, Nov 21, 2014
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    • "Second, treatment with attractant lipids or toxic compounds, such as isoamyl alcohol, lead to changes in the reversal periods, which depends on signaling (through Dif and Frz) and specifically, when Frz is involved, adaptation by receptor methylation (McBride et al., 1992; Kearns & Shimkets, 1998). Third, while clear taxis behaviors remain to be observed in individual cells, multicellular swarms show directed responses toward a nutrient or prey bacteria (Shi et al., 1993; Berleman et al., 2008; Taylor & Welch, 2008). "
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    ABSTRACT: In bird flocks, fish schools, and many other living organisms, regrouping among individuals of the same kin is frequently an advantageous strategy to survive, forage, and face predators. However, these behaviors are costly because the community must develop regulatory mechanisms to coordinate and adapt its response to rapid environmental changes. In principle, these regulatory mechanisms, involving communication between individuals, may also apply to cellular systems which must respond collectively during multicellular development. Dissecting the mechanisms at work requires amenable experimental systems, for example, developing bacteria. Myxococcus xanthus, a Gram-negative delatproteobacterium, is able to coordinate its motility in space and time to swarm, predate, and grow millimeter-size spore-filled fruiting bodies. A thorough understanding of the regulatory mechanisms first requires studying how individual cells move across solid surfaces and control their direction of movement, which was recently boosted by new cell biology techniques. In this review, we describe current molecular knowledge of the motility mechanism and its regulation as a lead-in to discuss how multicellular cooperation may have emerged from several layers of regulation: chemotaxis, cell-cell signaling, and the extracellular matrix. We suggest that Myxococcus is a powerful system to investigate collective principles that may also be relevant to other cellular systems.
    Full-text · Article · Sep 2011 · FEMS microbiology reviews
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    • "Myxococcus xanthus is a Gram negative soil bacterium that displays a complex life cycle. Survival skills have been honed well and include predation of other organisms (Berleman et al., 2008), multiple motility systems that allow cells to adapt to different environmental conditions (Shi & Zusman, 1993), and the ability to develop fruiting bodies filled with heat and desiccation-resistant spores in response to starvation (Kaiser, 2003). Starvation initiates a complicated developmental pathway that involves the (p)ppGpp-dependent stringent response (Harris et al., 1998, Laue & Gill, 1995) and requires elaborate cell-cell signaling (Rolbetzki et al., 2008, Sogaard-Andersen, 2004, Sogaard-Andersen et al., 2003, Shimkets, 1999, Kim & Kaiser, 1990). "
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    ABSTRACT: Myxococcus xanthus can vary its phenotype or 'phase' to produce colonies that contain predominantly yellow or tan cells that differ greatly in their abilities to swarm, survive and develop. Yellow variants are proficient at swarming (++) and tend to lyse in liquid during stationary phase. In contrast, tan variants are deficient in swarming (+) and persist beyond stationary phase. The phenotypes and transcriptomes of yellow and tan variants were compared with mutants affected in phase variation. Thirty-seven genes were upregulated specifically in yellow variants including those for production of the yellow pigment, DKxanthene. A mutant in DKxanthene synthesis produced non-pigmented (tan) colonies but still phase varied for swarming suggesting that pigmentation is not the cause of phase variation. Disruption of a gene encoding a HTH-Xre-like regulator, highly expressed in yellow variants, abolished pigment production and blocked the ability of cells to switch from a swarm ++ to a swarm (+) phenotype, showing that HTH-Xre regulates phase variation. Among the four genes whose expression was increased in tan variants was pkn14, which encodes a serine-threonine kinase that regulates programmed cell death in Myxococcus via the MrpC-MazF toxin-antitoxin complex. High levels of phosphorylated Pkn14 may explain why tan cells enjoy enhanced survival.
    Full-text · Article · Jul 2011 · Molecular Microbiology
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    • "Such variation in the social phenotypes of clonal groups is likely to be important for competition outcomes both when physical or behavioural barriers hinder migration of genotypes across social groups (Gibbs et al. 2008) and in heterogeneous social groups as well (Buttery et al. 2009). Myxococcus xanthus (order Myxococcales, species of which are collectively known as the myxobacteria) is a prominent model organism for the study of microbial social behaviour (Berleman et al. 2008, Fiegna et al. 2006, Kaplan 2003, Shimkets 1990, Vos and Velicer 2009, Wu et al. 2007, Zusman et al. 2007). M. xanthus cells actively migrate through the soil in search of prey or other food sources using two genetically and mechanistically distinct motility systems, one of which involves cell-cell contact mediated by Type IV pili to function (Kaiser 2008). "
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    ABSTRACT: The soil bacterium Myxococcus xanthus is a model for the study of cooperative microbial behaviours such as social motility and fruiting body formation. Several M. xanthus developmental traits that are frequently quantified for laboratory strains are likely to be significant components of fitness in natural populations, yet little is known about the degree to which such traits vary in the wild and may therefore be subject to natural selection. Here, we have tested whether several key M. xanthus developmental life-history traits have diverged significantly among strains both from globally distant origins and from within a sympatric, centimetre-scale population. The isolates examined here were found to vary considerably, in a heritable manner, in their rate of developmental aggregation and in both their rate and efficiency of spore production. Isolates also varied in the nutrient-concentration threshold triggering spore formation and in the heat resistance of spores. The large diversity of developmental phenotypes documented here leads to questions regarding the relative roles of selection and genetic drift in shaping the diversity of local soil populations with respect to these developmental traits. It also raises the question of whether fitness in the wild is largely determined by traits that are expressed independent of social context or by behaviours that are expressed only in genetically heterogeneous social groups.
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