Siderophores and competition for iron govern myxobacterial predation dynamics.

Bacterial predators are decisive organisms that shape microbial ecosystems. In this study, we investigated the role of iron and siderophores during the predatory interaction between two rhizosphere bacteria: Myxococcus xanthus, an epibiotic predator, and Sinorhizobium meliloti, a bacterium that establishes nitrogen-fixing symbiosis with legumes. The results show that iron enhances the motility of the predator and facilitates its predatory capability, and that intoxication by iron is not used by the predator to prey, although oxidative stress increases in both bacteria during predation.

predation: an updated overview.

Bacterial predators are widely distributed across a variety of natural environments. Understanding predatory interactions is of great importance since they play a defining role in shaping microbial communities in habitats such as soils. is a soil-dwelling bacterial predator that can prey on Gram-positive and Gram-negative bacteria and even on eukaryotic microorganisms.

Transcriptomic response of to the predatory attack of .

Bacterial predation impacts microbial community structures, which can have both positive and negative effects on plant and animal health and on environmental sustainability. is an epibiotic soil predator with a broad range of prey, including , which establishes nitrogen-fixing symbiosis with legumes. During the - interaction, the predator must adapt its transcriptome to kill and lyse the target (predatosome), and the prey must orchestrate a transcriptional response (defensome) to protect itself against the biotic stress caused by the predatory attack.

Development versus predation: Transcriptomic changes during the lifecycle of .

is a multicellular bacterium with a complex lifecycle. It is a soil-dwelling predator that preys on a wide variety of microorganisms by using a group and collaborative epibiotic strategy. In the absence of nutrients this myxobacterium enters in a unique developmental program by using sophisticated and complex regulatory systems where more than 1,400 genes are transcriptional regulated to guide the community to aggregate into macroscopic fruiting bodies filled of environmentally resistant myxospores.

Mechanisms of Action of Non-Canonical ECF Sigma Factors.

Extracytoplasmic function (ECF) sigma factors are subunits of the RNA polymerase specialized in activating the transcription of a subset of genes responding to a specific environmental condition. The signal-transduction pathways where they participate can be activated by diverse mechanisms. The most common mechanism involves the action of a membrane-bound anti-sigma factor, which sequesters the ECF sigma factor, and releases it after the stimulus is sensed.

Copper and Melanin Play a Role in Predation on .

is a soil myxobacterium that exhibits a complex lifecycle with two multicellular stages: cooperative predation and development. During predation, myxobacterial cells produce a wide variety of secondary metabolites and hydrolytic enzymes to kill and consume the prey. It is known that eukaryotic predators, such as ameba and macrophages, introduce copper and other metals into the phagosomes to kill their prey by oxidative stress.

Transcriptome dynamics of the multicellular developmental program.

The bacterium exhibits a complex multicellular life cycle. In the presence of nutrients, cells prey cooperatively. Upon starvation, they enter a developmental cycle wherein cells aggregate to produce macroscopic fruiting bodies filled with resistant myxospores.

Metal-responsive RNA polymerase extracytoplasmic function (ECF) sigma factors.

In order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive.

The complex global response to copper in the multicellular bacterium Myxococcus xanthus.

The complex copper response of the multicellular proteobacterium M. xanthus includes structural genes similar to those described in other bacteria, such as P1B-type ATPases, multicopper oxidases, and heavy metal efflux systems. However, the two time-dependent expression profiles of the different copper systems are unique.

Myxobacteria: Moving, Killing, Feeding, and Surviving Together.

Myxococcus xanthus, like other myxobacteria, is a social bacterium that moves and feeds cooperatively in predatory groups. On surfaces, rod-shaped vegetative cells move in search of the prey in a coordinated manner, forming dynamic multicellular groups referred to as swarms. Within the swarms, cells interact with one another and use two separate locomotion systems.

In depth analysis of the mechanism of action of metal-dependent sigma factors: characterization of CorE2 from Myxococcus xanthus.

Extracytoplasmic function sigma factors represent the third pillar of signal-transduction mechanisms in bacteria. The variety of stimuli they recognize and mechanisms of action they use have allowed their classification into more than 50 groups. We have characterized CorE2 from Myxococcus xanthus, which belongs to group ECF44 and upregulates the expression of two genes when it is activated by cadmium and zinc.

Dissection of the sensor domain of the copper-responsive histidine kinase CorS from Myxococcus xanthus.

Myxococcus xanthus CorSR is a two-component system responsible for maintaining the response of this bacterium to copper. In the presence of this metal it upregulates, among others, the genes encoding the multicopper oxidase CuoA and the P1B -ATPase CopA. Dissection of the periplasmic sensor domain of the histidine kinase CorS by the analysis of a series of in-frame deletion mutants generated in this portion of the protein has revealed that copper sensing requires a region of 28 residues in the N terminus and another region of nine residues in the C terminus.

Rhizobial galactoglucan determines the predatory pattern of Myxococcus xanthus and protects Sinorhizobium meliloti from predation.

Myxococcus xanthus is a social bacterium that preys on prokaryotic and eukaryotic microorganisms. Co-culture of M. xanthus with reference laboratory strains and field isolates of the legume symbiont Sinorhizobium meliloti revealed two different predatory patterns that resemble frontal and wolf-pack attacks.

The Myxococcus xanthus two-component system CorSR regulates expression of a gene cluster involved in maintaining copper tolerance during growth and development.

Myxococcus xanthus is a soil-dwelling member of the δ-Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M.

PomZ, a ParA-like protein, regulates Z-ring formation and cell division in Myxococcus xanthus.

Accurate positioning of the division site is essential to generate appropriately sized daughter cells with the correct chromosome number. In bacteria, division generally depends on assembly of the tubulin homologue FtsZ into the Z-ring at the division site. Here, we show that lack of the ParA-like protein PomZ in Myxococcus xanthus resulted in division defects with the formation of chromosome-free minicells and filamentous cells.

A novel mechanism of bacterial adaptation mediated by copper-dependent RNA polymerase σ factors.

One of the mechanisms widely used by bacteria to adapt to their environment is mediated by alternative σ factors. Here we discuss the mechanism of action of a novel metal-dependent ECF σ factor, whose ability to bind DNA depends on the redox state of copper.

Comprehensive set of integrative plasmid vectors for copper-inducible gene expression in Myxococcus xanthus.

Myxococcus xanthus is widely used as a model system for studying gliding motility, multicellular development, and cellular differentiation. Moreover, M. xanthus is a rich source of novel secondary metabolites.

CorE from Myxococcus xanthus is a copper-dependent RNA polymerase sigma factor.

The dual toxicity/essentiality of copper forces cells to maintain a tightly regulated homeostasis for this metal in all living organisms, from bacteria to humans. Consequently, many genes have previously been reported to participate in copper detoxification in bacteria. Myxococcus xanthus, a prokaryote, encodes many proteins involved in copper homeostasis that are differentially regulated by this metal.

Myxococcus xanthus induces actinorhodin overproduction and aerial mycelium formation by Streptomyces coelicolor.

Interaction of the predatory myxobacterium Myxococcus xanthus with the non-motile, antibiotic producer Streptomyces coelicolor was examined using a variety of experimental approaches. Myxococcus xanthus cells prey on S. coelicolor, forming streams of ordered cells that lyse the S.

Expression and physiological role of three Myxococcus xanthus copper-dependent P1B-type ATPases during bacterial growth and development.

Myxococcus xanthus is a soil-dwelling bacterium that exhibits a complex life cycle comprising social behavior, morphogenesis, and differentiation. In order to successfully complete this life cycle, cells have to cope with changes in their environment, among which the presence of copper is remarkable. Copper is an essential transition metal for life, but an excess of copper provokes cellular damage by oxidative stress.

Differential regulation of six heavy metal efflux systems in the response of Myxococcus xanthus to copper.

Myxococcus xanthus has to cope with changes in its environment during growth and development. Among these factors, the concentration of copper is crucial due to the essential toxic effect of this metal, which forces the cells to maintain a tight homeostasis. The M.

Myxococcus xanthus Pph2 is a manganese-dependent protein phosphatase involved in energy metabolism.

The multicellular behavior of the myxobacterium Myxococcus xanthus requires the participation of an elevated number of signal-transduction mechanisms to coordinate the cell movements and the sequential changes in gene expression patterns that lead to the morphogenetic and differentiation events. These signal-transduction mechanisms are mainly based on two-component systems and on the reversible phosphorylation of protein targets mediated by eukaryotic-like protein kinases and phosphatases. Among all these factors, protein phosphatases are the elements that remain less characterized.

Detoxification of azo dyes by a novel pH-versatile, salt-resistant laccase from Streptomyces ipomoea.

A newly identified extracellular laccase produced by Streptomyces ipomoea CECT 3341 (SilA) was cloned and overexpressed, and its physicochemical characteristics assessed together with its capability to decolorize and detoxify an azotype dye. Molecular analysis of the deduced sequence revealed that SilA contains a TAT-type signal peptide at the N-terminus and only two cupredoxine domains; this is consistent with reports describing two other Streptomyces laccases but contrasts with most laccases, which contain three cupredoxine domains. The heterologous expression and purification of SilA revealed that the homodimer is the only active form of the enzyme.