Genetic clusters carrying <i>che</i> genes in <i>M. xanthus</i>.

<p>Genetic organization of the genes composing the eight <i>che</i> clusters encoding the putative components of the chemosensory apparatus in <i>Myxococcus xanthus</i>. Predicted genes are indicated with their locus_tag, and their annotations and assigned names. The color code indicates homologous genes.</p

List of <i>M. xanthus</i> MCPs.^b

a<p> =  Histidine kinase, Adenylate cyclase, Mcp, Phosphatase</p>b<p> =  Methyl accepting Chemotaxis Protein</p>c<p> =  Cyclase/Histidine kinases Associated Sensory Extracellular</p>d<p> =  CAlcium channels and CHEmotaxis receptors</p

Functional Organization of a Multimodular Bacterial Chemosensory Apparatus

<div><p>Chemosensory systems (CSS) are complex regulatory pathways capable of perceiving external signals and translating them into different cellular behaviors such as motility and development. In the δ-proteobacterium <i>Myxococcus xanthus</i>, chemosensing allows groups of cells to orient themselves and aggregate into specialized multicellular biofilms termed fruiting bodies. <i>M. xanthus</i> contains eight predicted CSS and 21 chemoreceptors. In this work, we systematically deleted genes encoding components of each CSS and chemoreceptors and determined their effects on <i>M. xanthus</i> social behaviors. Then, to understand how the 21 chemoreceptors are distributed among the eight CSS, we examined their phylogenetic distribution, genomic organization and subcellular localization. We found that, <i>in vivo</i>, receptors belonging to the same phylogenetic group colocalize and interact with CSS components of the respective phylogenetic group. Finally, we identified a large chemosensory module formed by three interconnected CSS and multiple chemoreceptors and showed that complex behaviors such as cell group motility and biofilm formation require regulatory apparatus composed of multiple interconnected Che-like systems.</p></div

<i>M. xanthus</i> MCPs and CSS are organized in three taxonomic groups.

<p>(A) Concatamers of <i>M. xanthus</i> Che protein sequences were generated as described in Methods. Based on PP values, the eight concatamers can be divided into Group 1 (green background), Group 2 (blue background) and Group 3 (pink background). (B) The tree generated for the 21 <i>M. xanthus</i> MCP homologs shows a similar partition in three groups. The MCPs in black belong to <i>che</i> operons, while the MCPs in color are the orphans. (C) A tree generated with the MCP conserved protein sequences involved in the MCP-CheW interaction (Vu et al., 2012) gives rise to the same distribution as in (B). The alignment of the protein sequences involved in the MCP-CheW interaction from <i>T. maritime </i><a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004164#pgen.1004164-Vu1" target="_blank">[41]</a> and <i>M. xanthus</i> MCPs is shown. Colors indicate residues with the same properties. Numbers at nodes in (A) and (B) indicate posterior probabilities (PP) computed by MrBayes and bootstrap values (BV) computed by PhyML. Only PP and BV above 0.5 and 50% are shown. The scale bars represent the average number of substitutions per site.</p

MCPs colocalization analysis.

<p>(A) Fluorescence micrographs of <i>mcp5-mCherry mcpM-gfp</i> and <i>frzCD-gfp aglZ-mCherry</i> cells are shown as examples. From (B) to (G) scatterplots of individual red and green pixel intensities of double-labeled cells are shown. (H) Average Pearson's correlation coefficients (PCCs) each calculated from ten scatterplots per strain.</p

<i>ΔcheA</i> triple mutants have restored phenotypes as compared to single and double mutants.

<p>(A) Motility was measured after 48 h. The colony spreading of each mutant was normalized with the one of a <i>ΔpilA</i> strain <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004164#pgen.1004164-Battesti1" target="_blank">[68]</a> completely incapable of S motility, to exclude cell growth effects. Error bars indicate standard deviations. The star corresponds to <i>p</i><0.005. (B) <i>ΔcheA</i> fruiting body formation images at 72 h are shown.</p

MCP-GFP fusions localize in multiple dynamic clusters in cells.

<p>(A) In the first row, fluorescence (left) and overlay between fluorescence and phase contrast images (right) are shown for each MCP-GFP. In the bottom row, <i>n</i> clusters (numbers indicated above the histograms) were analyzed for each <i>mcp-gfp</i> strain and their relative position in cells in the <i>y</i>-axis is shown (0.0 indicate the center of the cell along the <i>y</i>-axis). Bars indicate the fraction of clusters localizing in the corresponding position in the <i>y</i>-axis. (B) Average number of clusters for each MCP-GFP. (<b>C</b>) Box plots indicate the medians of the product of the relative cell length and the total distance covered by the MCP-GFP clusters *  = <i>p</i><0.05; **  = <i>p</i><0. 5E-04 (refer also to Methods, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004164#pgen.1004164.s011" target="_blank">Table S2</a> and <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004164#pgen.1004164.s004" target="_blank">Figure S4</a>).</p

List of <i>M. xanthus</i> CheB and CheR.

<p>* incomplete CheR domain.</p><p>** CheR short Nter domain + CheR S-adenosyl-L-methionine binding domain.</p

List of <i>M. xanthus</i> CheA, CheW and CheY.

<p>List of <i>M. xanthus</i> CheA, CheW and CheY.</p

Genetic clusters carrying <i>che</i> genes in <i>M. xanthus</i>.

<p>Genetic organization of the genes composing the eight <i>che</i> clusters encoding the putative components of the chemosensory apparatus in <i>Myxococcus xanthus</i>. Predicted genes are indicated with their locus_tag, and their annotations and assigned names. The color code indicates homologous genes.</p