Infectious polymorphic toxins delivered by outer membrane exchange discriminate kin in myxobacteria
- University of Wyoming, United States
- University of California, United States
Figures
Figure 1
SitA1 is the swarm inhibition determinant.
(A) sitBAI1 operon found on one of the Mx-alpha elements that was lost from DK1622. SS, signal sequence. (B) Swarm inhibition assays with indicated motile and nonmotile strains. White arrow …
Figure 2 with 3 supplements
SitA polymorphic toxins found on Mx-alpha units are delivered by OME.
(A) Strain DK101 (the ancestor of DK1622) carries three Mx-alpha repeats, whereas DK1622 retains only one copy. Each Mx-alpha unit contains a unique sitBAI cassette. SitB proteins contain type I …
Figure 2—figure supplement 1
Morphology of SitA-poisoned target cells.
Target cells (red) were competed with sitBAI inhibitor strains or a ∆sitBAI mock inhibitor control at a 20 to 1 ratio. After 24 hr on agar media, cells were harvested and placed on glass slides for …
Figure 2—figure supplement 2
SitA-CTD expression in M. xanthus is toxic.
(A) Culture growth of strains was measured over 24 hr, in the presence or absence of IPTG. Each strain expressed a SitA-CTD or a control protein (tdTomato) from an IPTG-inducible promoter. Red …
Figure 2—figure supplement 3
Heterologous sitAI cassettes from M. fulvus HW-1 are active in DK1622.
sitA3Mf1 (SitA3 homolog, LILAB_02580) and its associated sitI3Mf1, or sitA1Mf1 (SitA1 homolog, LILAB_05795) and its associated sitB1Mf1 and sitI1Mf1, were expressed in DK1622. Competitive indices …
Figure 3 with 1 supplement
Toxic function of SitA1 and SitA3 CTDs.
(A) SitA3-CTD is a toxic tRNase. Expression of the indicated CTDs was induced with arabinose in E. coli, and cell growth monitored by measuring the optical density of the cultures at 600 nm (OD600). …
Figure 3—figure supplement 1
Alignment of SitA3-CTD with CdiA-CTD tRNase toxins.
SitA3-CTD shares homology with CdiA-CTD domains from Burkholderia pseudomallei 1026b (BP1026B_II2207) and Yersinia pseudotuberculosis YPIII (Ga0077885_11584). Predicted nuclease active-site residues …
Figure 4
sitAI alleles determine the social compatibility of M. xanthus swarms.
(A) M. xanthus colonies expressing identical sitAI cassettes merge (as illustrated by the green arrow) when spotted adjacent to one another (top of each column). Strains that express different sitAI …
Figure 5 with 1 supplement
SitA toxins are serially transferred by OME.
(A) Viable cells (CFU) of a target population as a function of inhibitor to target cell ratio quantifies the efficiency of SitA1 and OME delivery. Strains were co-cultured on agar for 48 hr at …
Figure 5—figure supplement 1
TraA is not transferred during OME.
(A) TraA-mCherry fusion protein is functional. Cells expressing TraA-mCherry were mixed with either traA+ (top) or ∆traA (bottom) donors that express an OM lipoprotein reporter, SSOM-sfGFP. Arrows …
Figure 6
SitB contributes to SitA function and serial transfer.
(A) The indicated SitA1 inhibitor strains were co-cultured with target cells at three different inhibitor to target ratios. Competitive index was measured at 24 hr by counting the ratios of …
Figure 7
TraA and SitA are dominant determinants of competitive outcome within TraA recognition groups.
(A) Line graphs represent strain ratio over time when the three indicated, DK1622-derived strains, which were fluorescently labelled, were competed with wild isolates (A66, A88, DK801). These …
Figure 8
Model for serial transfer of SitA.
(A) SitA is delivered cell-to-cell by OME. After OME, SitA may enter the cytoplasm or linger (lag) in the OM. (B) In the delayed entry model, the infected cell can undergo OME of SitA to another …
Additional files
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Supplementary file 1
Homologs of SitA toxins.
- https://doi.org/10.7554/eLife.29397.016
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Supplementary file 2
Strains, plasmids, and primers used in this study.
- https://doi.org/10.7554/eLife.29397.017
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Supplementary file 3
Alignment of representative SitA toxins and their predicted functional annotations.
- https://doi.org/10.7554/eLife.29397.018
