scholarly journals Gliding Mutants of Myxococcus xanthuswith High Reversal Frequencies and Small Displacements

1999 ◽  
Vol 181 (8) ◽  
pp. 2593-2601 ◽  
Author(s):  
Alfred M. Spormann ◽  
Dale Kaiser
Keyword(s):  
Single Cell ◽  
Cell Movement ◽  
Gliding Motility ◽  
Wild Type ◽  
Epistasis Analysis ◽  
Type Iv ◽  
Reversal Frequency ◽  
Order Of Magnitude ◽  
Dependent Cell ◽  
Mutant Cells

ABSTRACT Myxococcus xanthus cells move on a solid surface by gliding motility. Several genes required for gliding motility have been identified, including those of the A- and S-motility systems as well as the mgl and frz genes. However, the cellular defects in gliding movement in many of these mutants were unknown. We conducted quantitative, high-resolution single-cell motility assays and found that mutants defective inmglAB or in cglB, an A-motility gene, reversed the direction of gliding at frequencies which were more than 1 order of magnitude higher than that of wild type cells (2.9 min−1for ΔmglAB mutants and 2.7 min−1 forcglB mutants, compared to 0.17 min−1 for wild-type cells). The average gliding speed of ΔmglABmutant cells was 40% of that of wild-type cells (on average 1.9 μm/min for ΔmglAB mutants, compared to 4.4 μm/min for wild-type cells). The mglA-dependent reversals and gliding speeds were dependent on the level of intracellular MglA protein: mglB mutant cells, which contain only 15 to 20% of the wild-type level of MglA protein, glided with an average reversal frequency of about 1.8 min−1 and an average speed of 2.6 μm/min. These values range between those exhibited by wild-type cells and by ΔmglAB mutant cells. Epistasis analysis of frz mutants, which are defective in aggregation and in single-cell reversals, showed that a frzD mutation, but not a frzE mutation, partially suppressed themglA phenotype. In contrast to mgl mutants,cglB mutant cells were able to move with wild-type speeds only when in close proximity to each other. However, under those conditions, these mutant cells were found to glide less often with those speeds. By analyzing double mutants, the high reversing movements and gliding speeds of cglB cells were found to be strictly dependent on type IV pili, encoded by S-motility genes, whereas the high-reversal pattern ofmglAB cells was only partially reduced by apilR mutation. These results suggest that the MglA protein is required for both control of reversal frequency and gliding speed and that in the absence of A motility, type IV pilus-dependent cell movement includes reversals at high frequency. Furthermore, mglAB mutants behave as if they were severely defective in A motility but only partially defective in S motility.

scholarly journals Genetic and Molecular Analysis of cglB, a Gene Essential for Single-Cell Gliding in Myxococcus xanthus

1999 ◽  
Vol 181 (14) ◽  
pp. 4381-4390 ◽  
Author(s):  
Ana M. Rodriguez ◽  
Alfred M. Spormann
Keyword(s):  
Single Cell ◽  
Myxococcus Xanthus ◽  
Gliding Motility ◽  
Open Reading Frames ◽  
Wild Type Allele ◽  
Wild Type ◽  
Isolated Cells ◽  
Type Allele ◽  
C Terminus ◽  
Mutant Cells

ABSTRACT Gliding movements of individual isolated Myxococcus xanthus cells depend on the genes of the A-motility system (agl and cgl genes). Mutants carrying defects in those genes are unable to translocate as isolated cells on solid surfaces. The motility defect of cgl mutants can be transiently restored to wild type by extracellular complementation upon mixing mutant cells with wild-type or other motility mutant cells. To develop a molecular understanding of the function of a Cgl protein in gliding motility, we cloned the cglB wild-type allele by genetic complementation of the mutant phenotype. The nucleotide sequence of a 2.85-kb fragment was determined and shown to encode two complete open reading frames. The CglB protein was determined to be a 416-amino-acid putative lipoprotein with an unusually high cysteine content. The CglB antigen localized to the membrane fraction. The swarming and gliding defects of a constructed ΔcglBmutant were fully restored upon complementation with thecglB wild-type allele. Experiments with a cglBallele encoding a CglB protein with a polyhistidine tag at the C terminus showed that this allele also promoted wild-type levels of swarming and single-cell gliding, but was unable to stimulate ΔcglB cells to move. Possible functions of CglB as a mechanical component or as a signal protein in single cell gliding are discussed.

scholarly journals Colony spreading of the gliding bacterium Flavobacterium johnsoniae in the absence of the motility adhesin SprB

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Keiko Sato ◽  
Masami Naya ◽  
Yuri Hatano ◽  
Yoshio Kondo ◽  
Mari Sato ◽  
...  
Keyword(s):  
Soft Agar ◽  
Gliding Motility ◽  
Wild Type ◽  
Initial Cell ◽  
Flavobacterium Johnsoniae ◽  
Seeking Behavior ◽  
Colony Spreading ◽  
Gliding Bacterium ◽  
Mutant Cells ◽  
Scanning Electron

AbstractColony spreading of Flavobacterium johnsoniae is shown to include gliding motility using the cell surface adhesin SprB, and is drastically affected by agar and glucose concentrations. Wild-type (WT) and ΔsprB mutant cells formed nonspreading colonies on soft agar, but spreading dendritic colonies on soft agar containing glucose. In the presence of glucose, an initial cell growth-dependent phase was followed by a secondary SprB-independent, gliding motility-dependent phase. The branching pattern of a ΔsprB colony was less complex than the pattern formed by the WT. Mesoscopic and microstructural information was obtained by atmospheric scanning electron microscopy (ASEM) and transmission EM, respectively. In the growth-dependent phase of WT colonies, dendritic tips spread rapidly by the movement of individual cells. In the following SprB-independent phase, leading tips were extended outwards by the movement of dynamic windmill-like rolling centers, and the lipoproteins were expressed more abundantly. Dark spots in WT cells during the growth-dependent spreading phase were not observed in the SprB-independent phase. Various mutations showed that the lipoproteins and the motility machinery were necessary for SprB-independent spreading. Overall, SprB-independent colony spreading is influenced by the lipoproteins, some of which are involved in the gliding machinery, and medium conditions, which together determine the nutrient-seeking behavior.

scholarly journals A Dictyostelium mutant deficient in severin, an F-actin fragmenting protein, shows normal motility and chemotaxis.

1989 ◽  
Vol 108 (3) ◽  
pp. 985-995 ◽  
Author(s):  
E André ◽  
M Brink ◽  
G Gerisch ◽  
G Isenberg ◽  
A Noegel ◽  
...  
Keyword(s):  
Cell Function ◽  
Polyclonal Antibodies ◽  
Deae Cellulose ◽  
Cell Movement ◽  
Processing System ◽  
Chemical Mutagenesis ◽  
Deficient Mutant ◽  
Wild Type ◽  
Coding Region ◽  
Mutant Cells

A severin deficient mutant of Dictyostelium discoideum has been isolated by the use of colony immunoblotting after chemical mutagenesis. In homogenates of wild-type cells, severin is easily detected as a very active F-actin fragmenting protein. Tests for severin in the mutant, HG1132, included viscometry for the assay of F-actin fragmentation in fractions from DEAE-cellulose columns, labeling of blots with monoclonal and polyclonal antibodies, and immunofluorescent-labeling of cryosections. Severin could not be detected in the mutant using these methods. The mutation in HG1132 is recessive and has been mapped to linkage group VII. The mutant failed to produce the normal severin mRNA, but small amounts of a transcript that was approximately 100 bases larger than the wild-type mRNA were detected in the mutant throughout all stages of development. On the DNA level a new Mbo II restriction site was found in the mutant within the coding region of the severin gene. The severin deficient mutant cells grew at an approximately normal rate, aggregated and formed fruiting bodies with viable spores. By the use of an image processing system, speed of cell movement, turning rates, and precision of chemotactic orientation in a stable gradient of cyclic AMP were quantitated, and no significant differences between wild-type and mutant cells were found. Thus, under the culture conditions used, severin proved to be neither essential for growth of D. discoideum nor for any cell function that is important for aggregation or later development.

scholarly journals Flavobacterium johnsoniae gldN and gldO Are Partially Redundant Genes Required for Gliding Motility and Surface Localization of SprB

2009 ◽  
Vol 192 (5) ◽  
pp. 1201-1211 ◽  
Author(s):  
Ryan G. Rhodes ◽  
Mudiarasan Napoleon Samarasam ◽  
Abhishek Shrivastava ◽  
Jessica M. van Baaren ◽  
Soumya Pochiraju ◽  
...  
Keyword(s):  
Protein Secretion ◽  
Deletion Mutant ◽  
Gliding Motility ◽  
Selection Strategy ◽  
Wild Type ◽  
Flavobacterium Johnsoniae ◽  
Redundant Genes ◽  
Surface Localization ◽  
Gliding Bacterium ◽  
Mutant Cells

ABSTRACT Cells of the gliding bacterium Flavobacterium johnsoniae move rapidly over surfaces. Mutations in gldN cause a partial defect in gliding. A novel bacteriophage selection strategy was used to aid construction of a strain with a deletion spanning gldN and the closely related gene gldO in an otherwise wild-type F. johnsoniae UW101 background. Bacteriophage transduction was used to move a gldN mutation into F. johnsoniae UW101 to allow phenotypic comparison with the gldNO deletion mutant. Cells of the gldN mutant formed nonspreading colonies on agar but retained some ability to glide in wet mounts. In contrast, cells of the gldNO deletion mutant were completely nonmotile, indicating that cells require GldN, or the GldN-like protein GldO, to glide. Recent results suggest that Porphyromonas gingivalis PorN, which is similar in sequence to GldN, has a role in protein secretion across the outer membrane. Cells of the F. johnsoniae gldNO deletion mutant were defective in localization of the motility protein SprB to the cell surface, suggesting that GldN may be involved in secretion of components of the motility machinery. Cells of the gldNO deletion mutant were also deficient in chitin utilization and were resistant to infection by bacteriophages, phenotypes that may also be related to defects in protein secretion.

scholarly journals Agrobacterium tumefaciens Twin-Arginine-Dependent Translocation Is Important for Virulence, Flagellation, and Chemotaxis but Not Type IV Secretion

2003 ◽  
Vol 185 (3) ◽  
pp. 760-771 ◽  
Author(s):  
Zhiyong Ding ◽  
Peter J. Christie
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Type Iv Secretion ◽  
Anaerobic Growth ◽  
Induction Medium ◽  
Rich Medium ◽  
Wild Type ◽  
Prolonged Incubation ◽  
Type Iv ◽  
Tat System ◽  
Mutant Cells

ABSTRACT This study characterized the contribution of the twin-arginine translocation (TAT) pathway to growth, motility, and virulence of the phytopathogen Agrobacterium tumefaciens. In contrast to wild-type strain A348, a tatC null mutant failed to export the green fluorescent protein fused to the trimethylamine N-oxide reductase (TorA) signal sequence or to grow on nitrate as a sole electron acceptor during anaerobic growth. The tatC mutant displayed defects in growth rate and cell division but not in cell viability, and it also released abundant levels of several proteins into the culture supernatant when grown in rich medium or in vir induction minimal medium. Nearly all A348 cells were highly motile in both rich and minimal media. By contrast, approximately 0.1% of the tatC mutant cells were motile in rich medium, and <0.01% were motile in vir induction medium. Nonmotile tatC mutant cells lacked detectable flagella, whereas motile tatC mutant cells collected from the edge of a motility halo possessed flagella but not because of reversion to a functional TAT system. Motile tatC cells failed to exhibit chemotaxis toward sugars under aerobic conditions or towards nitrate under anaerobic conditions. The tatC mutant was highly attenuated for virulence, only occasionally (∼15% of inoculations) inciting formation of small tumors on plants after a prolonged incubation period of 6 to 8 weeks. However, an enriched subpopulation of motile tatC mutants exhibited enhanced virulence compared to the nonmotile variants. Finally, the tatC mutant transferred T-DNA and protein effectors to plant cells and a mobilizable IncQ plasmid to agrobacterial recipients at wild-type levels. Together, our findings establish that, in addition to its role in secretion of folded cofactor-bound enzymes functioning in alternative respiration, the TAT system of A. tumefaciens is an important virulence determinant. Furthermore, this secretion pathway contributes to flagellar biogenesis and chemotactic responses but not to sensory perception of plant signals or the assembly of a type IV secretion system.

scholarly journals Single Cells Exhibit Differing Behavioral Phases during Early Stages of Pseudomonas aeruginosa Swarming

2019 ◽  
Vol 201 (19) ◽  
Author(s):  
Chinedu S. Madukoma ◽  
Peixian Liang ◽  
Aleksandar Dimkovikj ◽  
Jianxu Chen ◽  
Shaun W. Lee ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Motility ◽  
Single Cell ◽  
High Cell Density ◽  
Single Cells ◽  
High Cell ◽  
Wild Type ◽  
Content Type ◽  
Type Iv ◽  
The Many

ABSTRACT Pseudomonas aeruginosa is among the many bacteria that swarm, where groups of cells coordinate to move over surfaces. It has been challenging to determine the behavior of single cells within these high-cell-density swarms. To track individual cells within P. aeruginosa swarms, we imaged a fluorescently labeled subset of the larger population. Single cells at the advancing swarm edge varied in their motility dynamics as a function of time. From these data, we delineated four phases of early swarming prior to the formation of the tendril fractals characteristic of P. aeruginosa swarming by collectively considering both micro- and macroscale data. We determined that the period of greatest single-cell motility does not coincide with the period of greatest collective swarm expansion. We also noted that flagellar, rhamnolipid, and type IV pilus motility mutants exhibit substantially less single-cell motility than the wild type. IMPORTANCE Numerous bacteria exhibit coordinated swarming motion over surfaces. It is often challenging to assess the behavior of single cells within swarming communities due to the limitations of identifying, tracking, and analyzing the traits of swarming cells over time. Here, we show that the behavior of Pseudomonas aeruginosa swarming cells can vary substantially in the earliest phases of swarming. This is important to establish that dynamic behaviors should not be assumed to be constant over long periods when predicting and simulating the actions of swarming bacteria.

scholarly journals Twitching Motility Is Essential for Virulence in Dichelobacter nodosus

2008 ◽  
Vol 190 (9) ◽  
pp. 3323-3335 ◽  
Author(s):  
Xiaoyan Han ◽  
Ruth M. Kennan ◽  
John K. Davies ◽  
Leslie A. Reddacliff ◽  
Om P. Dhungyel ◽  
...  
Keyword(s):  
Cell Movement ◽  
Foot Rot ◽  
Twitching Motility ◽  
Wild Type ◽  
Cell Adherence ◽  
Secretion Pathway ◽  
Dichelobacter Nodosus ◽  
Fimbrial Subunit ◽  
Type Iv ◽  
Protease Secretion

ABSTRACTType IV fimbriae are essential virulence factors ofDichelobacter nodosus, the principal causative agent of ovine foot rot. ThefimAfimbrial subunit gene is required for virulence, butfimAmutants exhibit several phenotypic changes and it is not certain if the effects on virulence result from the loss of type IV fimbria-mediated twitching motility, cell adherence, or reduced protease secretion. We showed that mutation of either thepilTorpilUgene eliminated the ability to carry out twitching motility. However, thepilTmutants displayed decreased adhesion to epithelial cells and reduced protease secretion, whereas thepilUmutants had wild-type levels of extracellular protease secretion and adherence. These data provided evidence that PilT is required for the type IV fimbria-dependent protease secretion pathway inD. nodosus. It was postulated that sufficient fimbrial retraction must occur in thepilUmutants to allow protease secretion, but not twitching motility, to take place. Although no cell movement was detected in apilUmutant ofD. nodosus, aberrant motion was detected in an equivalent mutant ofPseudomonas aeruginosa. These observations explain how inD. nodosusprotease secretion can occur in apilUmutant but not in apilTmutant. In addition, virulence studies with sheep showed that both thepilTandpilUmutants were avirulent, providing evidence that mutation of the type IV fimbrial system affects virulence by eliminating twitching motility, not by altering cell adherence or protease secretion.

scholarly journals Dictyostelium RasG Is Required for Normal Motility and Cytokinesis, But Not Growth

1997 ◽  
Vol 138 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Richard I. Tuxworth ◽  
Janet L. Cheetham ◽  
Laura M. Machesky ◽  
George B. Spiegelmann ◽  
Gerald Weeks ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Movement ◽  
Ras Proteins ◽  
Wild Type ◽  
Principal Role ◽  
Ras Protein ◽  
Wide Range ◽  
And Control ◽  
Mutant Cells ◽  
Lamellipodia Formation

RasG is the most abundant Ras protein in growing Dictyostelium cells and the closest relative of mammalian Ras proteins. We have generated null mutants in which expression of RasG is completely abolished. Unexpectedly, RasG− cells are able to grow at nearly wild-type rates. However, they exhibit defective cell movement and a wide range of defects in the control of the actin cytoskeleton, including a loss of cell polarity, absence of normal lamellipodia, formation of unusual small, punctate polymerized actin structures, and a large number of abnormally long filopodia. Despite their lack of polarity and abnormal cytoskeleton, mutant cells perform normal chemotaxis. However, rasG− cells are unable to perform normal cytokinesis, becoming multinucleate when grown in suspension culture. Taken together, these data suggest a principal role for RasG in coordination of cell movement and control of the cytoskeleton.

scholarly journals A forward genetic screen identifies a negative regulator of rapid Ca2+-dependent cell egress (MS1) in the intracellular parasite Toxoplasma gondii

2017 ◽  
Vol 292 (18) ◽  
pp. 7662-7674 ◽  
Author(s):  
James M. McCoy ◽  
Rebecca J. Stewart ◽  
Alessandro D. Uboldi ◽  
Dongdi Li ◽  
Jan Schröder ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Genetic Screen ◽  
Gliding Motility ◽  
Negative Regulator ◽  
Host Cells ◽  
Wild Type ◽  
Forward Genetic Screen ◽  
Apicomplexan Parasites ◽  
Dependent Cell ◽  
Dependent Protein

Toxoplasma gondii, like all apicomplexan parasites, uses Ca2+ signaling pathways to activate gliding motility to power tissue dissemination and host cell invasion and egress. A group of “plant-like” Ca2+-dependent protein kinases (CDPKs) transduces cytosolic Ca2+ flux into enzymatic activity, but how they function is poorly understood. To investigate how Ca2+ signaling activates egress through CDPKs, we performed a forward genetic screen to isolate gain-of-function mutants from an egress-deficient cdpk3 knockout strain. We recovered mutants that regained the ability to egress from host cells that harbored mutations in the gene Suppressor of Ca2+-dependent Egress 1 (SCE1). Global phosphoproteomic analysis showed that SCE1 deletion restored many Δcdpk3-dependent phosphorylation events to near wild-type levels. We also show that CDPK3-dependent SCE1 phosphorylation is required to relieve its suppressive activity to potentiate egress. In summary, our work has uncovered a novel component and suppressor of Ca2+-dependent cell egress during Toxoplasma lytic growth.

scholarly journals Pattern-formation mechanisms in motility mutants of Myxococcus xanthus

2012 ◽  
Vol 2 (6) ◽  
pp. 774-785 ◽  
Author(s):  
Jörn Starruß ◽  
Fernando Peruani ◽  
Vladimir Jakovljevic ◽  
Lotte Søgaard-Andersen ◽  
Andreas Deutsch ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Cell Motility ◽  
Collective Motion ◽  
Myxococcus Xanthus ◽  
Vortex Formation ◽  
Careful Analysis ◽  
Gliding Motility ◽  
Formation Mechanisms ◽  
Wild Type ◽  
Type Iv

Formation of spatial patterns of cells is a recurring theme in biology and often depends on regulated cell motility. Motility of the rod-shaped cells of the bacterium Myxococcus xanthus depends on two motility machineries, type IV pili (giving rise to S-motility) and the gliding motility apparatus (giving rise to A-motility). Cell motility is regulated by occasional reversals. Moving M. xanthus cells can organize into spreading colonies or spore-filled fruiting bodies, depending on their nutritional status. To ultimately understand these two pattern-formation processes and the contributions by the two motility machineries, as well as the cell reversal machinery, we analyse spatial self-organization in three M. xanthus strains: (i) a mutant that moves unidirectionally without reversing by the A-motility system only, (ii) a unidirectional mutant that is also equipped with the S-motility system, and (iii) the wild-type that, in addition to the two motility systems, occasionally reverses its direction of movement. The mutant moving by means of the A-engine illustrates that collective motion in the form of large moving clusters can arise in gliding bacteria owing to steric interactions of the rod-shaped cells, without the need of invoking any biochemical signal regulation. The two-engine strain mutant reveals that the same phenomenon emerges when both motility systems are present, and as long as cells exhibit unidirectional motion only. From the study of these two strains, we conclude that unidirectional cell motion induces the formation of large moving clusters at low and intermediate densities, while it results in vortex formation at very high densities. These findings are consistent with what is known from self-propelled rod models, which strongly suggests that the combined effect of self-propulsion and volume exclusion interactions is the pattern-formation mechanism leading to the observed phenomena. On the other hand, we learn that when cells occasionally reverse their moving direction, as observed in the wild-type, cells form small but strongly elongated clusters and self-organize into a mesh-like structure at high enough densities. These results have been obtained from a careful analysis of the cluster statistics of ensembles of cells, and analysed in the light of a coagulation Smoluchowski equation with fragmentation.

Sign in / Sign up

Export Citation Format

Share Document