scholarly journals Myxococcus xanthus Displays Frz-Dependent Chemokinetic Behavior during Vegetative Swarming

1998 ◽  
Vol 180 (2) ◽  
pp. 440-443 ◽  
Author(s):  
Mandy J. Ward ◽  
Kenny C. Mok ◽  
David R. Zusman
Keyword(s):  
Signal Transduction ◽  
Life Cycle ◽  
Cell Density ◽  
Myxococcus Xanthus ◽  
Microscopic Analysis ◽  
Time Lapse ◽  
Complex Life Cycle ◽  
Signal Transduction System ◽  
Nutrient Levels ◽  
Time Lapse Video

ABSTRACT Myxococcus xanthus has been shown to utilize both directed (tactic) and undirected (kinetic) movements during different stages of its complex life cycle. We have used time-lapse video microscopic analysis to separate tactic and kinetic behaviors associated specifically with vegetatively swarming cells. Isolated individual cells separated by a thin agar barrier from mature swarms showed significant increases in gliding velocity compared to that of similar cells some distance from the swarm. This orthokinetic behavior was independent of the frequency of reversals of gliding direction (klinokinesis) but did require both the Frz signal transduction system and S-motility. We propose that M. xanthus uses Frz-dependent, auto-orthokinetic behavior to facilitate the dispersal of cells under conditions where both cell density and nutrient levels are high.

scholarly journals An ABC Transporter Plays a Developmental Aggregation Role in Myxococcus xanthus

1998 ◽  
Vol 180 (21) ◽  
pp. 5697-5703 ◽  
Author(s):  
Mandy J. Ward ◽  
Kenny C. Mok ◽  
David P. Astling ◽  
Helen Lew ◽  
David R. Zusman
Keyword(s):  
Signal Transduction ◽  
Life Cycle ◽  
Abc Transporter ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Complex Life Cycle ◽  
Upstream Region ◽  
Atp Binding ◽  
Cloning And Sequencing ◽  
Atp Binding Cassette

ABSTRACT Myxococcus xanthus is a gram-negative bacterium which has a complex life cycle. Autochemotaxis, a process whereby cells release a self-generated signaling molecule, may be the principal mechanism facilitating directed motility in both the vegetative swarming and developmental aggregation stages of this life cycle. The process requires the Frz signal transduction system, including FrzZ, a protein which is composed of two domains, both showing homology to the enteric chemotaxis response regulator CheY. The first domain of FrzZ (FrzZ1), when expressed as bait in the yeast two-hybrid system and screened against a library, was shown to potentially interact with the C-terminal portion of a protein encoding an ATP-binding cassette (AbcA). The activation domain-AbcA fusion protein did not interact with the second domain of FrzZ (FrzZ2) or with two other M. xanthus response regulator-containing proteins presented as bait, suggesting that the FrzZ1-AbcA interaction may be specific. Cloning and sequencing of the upstream region of the abcA gene showed the ATP-binding cassette to be linked to a large hydrophobic, potentially membrane-spanning domain. This domain organization is characteristic of a subgroup of ABC transporters which perform export functions. Cloning and sequencing downstream of abcAindicated that the ABC transporter is at the start of an operon containing three open reading frames. An insertion mutation in theabcA gene resulted in cells displaying the frizzy aggregation phenotype, providing additional evidence that FrzZ and AbcA may be part of the same signal transduction pathway. Cells with mutations in genes downstream of abcA showed no developmental defects. Analysis of the proposed exporter role of AbcA in cell mixing experiments showed that the ABC transporter mutant could be rescued by extracellular complementation. We speculate that the AbcA protein may be involved in the export of a molecule required for the autochemotactic process.

scholarly journals Nanoprinting onto cells

2005 ◽  
Vol 3 (8) ◽  
pp. 393-398 ◽  
Author(s):  
Adam S.G Curtis ◽  
Matthew J Dalby ◽  
Nikolaj Gadegaard
Keyword(s):  
Gene Expression ◽  
Flat Surface ◽  
Cell Signalling ◽  
Time Lapse ◽  
Signal Transduction System ◽  
Similar Time ◽  
Video Studies ◽  
Cell Gene Expression ◽  
Cell Gene ◽  
Time Lapse Video

Growing cells on surfaces bearing nanotopography signals makes many changes in cell gene expression and downstream changes in phenotype but the mechanisms for this have, so far, been obscure. We consider the question of whether the topography directly nanoimprints onto the cell as a component of the signal transduction system. Evidence we present from SEM, TEM and fluorescence detection of the arrangements of cytoskeletal components is consistent with the possibility that cells are nanoimprinted by the substrate. The nanoprinting does not interfere with integrin-mediated adhesion processes and may perhaps work through them. Time-lapse video studies of cells moving from areas bearing nanotopography to flat areas and vice versa suggests that the nanoimprinting takes 1–6 h to appear on the cell and a similar time to disappear when the cell moves from a flat surface to a nanotopographic one and back. This nanoprinting of cells would appear to be a novel type of cell signalling.

scholarly journals Neutral and Phospholipids of the Myxococcus xanthus Lipodome during Fruiting Body Formation and Germination

2015 ◽  
Vol 81 (19) ◽  
pp. 6538-6547 ◽  
Author(s):  
Tilman Ahrendt ◽  
Hendrik Wolff ◽  
Helge B. Bode
Keyword(s):  
Life Cycle ◽  
Lipid Profile ◽  
De Novo ◽  
Membrane Lipids ◽  
Myxococcus Xanthus ◽  
Model Organism ◽  
Ether Lipid ◽  
Complex Life Cycle ◽  
Fruiting Body Formation ◽  
Content Type

ABSTRACTMyxobacteria are well-known for their complex life cycle, including the formation of spore-filled fruiting bodies. The model organismMyxococcus xanthusexhibits a highly complex composition of neutral and phospholipids, including triacylglycerols (TAGs), diacylglycerols (DAGs), phosphatidylethanolamines (PEs), phosphatidylglycerols (PGs), cardiolipins (CLs), and sphingolipids, including ceramides (Cers) and ceramide phosphoinositols (Cer-PIs). In addition, ether lipids have been shown to be involved in development and signaling. In this work, we describe the lipid profile ofM. xanthusduring its entire life cycle, including spore germination. PEs, representing one of the major components of the bacterial membrane, decreased by about 85% during development from vegetative rods to round myxospores, while TAGs first accumulated up to 2-fold before they declined 48 h after the induction of sporulation. Presumably, membrane lipids are incorporated into TAG-containing lipid bodies, serving as an intermediary energy source for myxospore formation. The ceramides Cer(d-19:0/iso-17:0) and Cer(d-19:0/16:0) accumulated 6-fold and 3-fold, respectively, after 24 h of development, identifying them to be novel putative biomarkers forM. xanthussporulation. The most abundant ether lipid, 1-iso-15:0-alkyl-2,3-di-iso-15:0-acyl glycerol (TG1), exhibited a lipid profile different from that of all TAGs during sporulation, reinforcing its signaling character. The absence of all these lipid profile changes in mutants during development supports the importance of lipids in myxobacterial development. During germination of myxospores, only thede novobiosynthesis of new cell membrane fatty acids was observed. The unexpected accumulation of TAGs also during germination might indicate a function of TAGs as intermediary storage lipids during this part of the life cycle as well.

scholarly journals Expression and Physiological Role of Three Myxococcus xanthus Copper-Dependent P1B-Type ATPases during Bacterial Growth and Development

2010 ◽  
Vol 76 (18) ◽  
pp. 6077-6084 ◽  
Author(s):  
Aurelio Moraleda-Muñoz ◽  
Juana Pérez ◽  
Antonio Luis Extremera ◽  
José Muñoz-Dorado
Keyword(s):  
Life Cycle ◽  
Expression Profiles ◽  
Myxococcus Xanthus ◽  
Physiological Role ◽  
Copper Homeostasis ◽  
Cellular Damage ◽  
Complex Life Cycle ◽  
Sequence Motifs ◽  
Dual Effect

ABSTRACT 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. This dual effect forces the cells to maintain a tight homeostasis. M. xanthus encodes a large number of genes with similarities to others reported previously to be involved in copper homeostasis, most of which are redundant. We have identified three genes that encode copper-translocating P1B-ATPases (designated copA, copB, and copC) that exhibit the sequence motifs and modular organizations of those that extrude Cu+. The expression of the ATPase copC has not been detected, but copA and copB are differentially regulated by the addition of external copper. However, while copB expression peaks at 2 h, copA is expressed at higher levels, and the maximum is reached much later. The fact that these expression profiles are nearly identical to those exhibited by the multicopper oxidases cuoA and cuoB suggests that the pairs CuoB-CopB and CuoA-CopA sequentially function to detoxify the cell. The deletion of any ATPase alters the expression profiles of other genes involved in copper homeostasis, such as the remaining ATPases or the Cus systems, yielding cells that are more resistant to the metal.

scholarly journals A DnaK Homolog in Myxococcus xanthus Is Involved in Social Motility and Fruiting Body Formation

1998 ◽  
Vol 180 (2) ◽  
pp. 218-224 ◽  
Author(s):  
Zhaomin Yang ◽  
Yongzhi Geng ◽  
Wenyuan Shi
Keyword(s):  
Life Cycle ◽  
Myxococcus Xanthus ◽  
Complex Life Cycle ◽  
Phenotypic Characterization ◽  
Fruiting Body Formation ◽  
Gram Negative ◽  
Body Formation ◽  
The Social ◽  
Cellular Aggregation ◽  
Social Motility

ABSTRACT Myxococcus xanthus is a gram-negative soil bacterium which exhibits a complex life cycle and social behavior. In this study, two developmental mutants of M. xanthus were isolated through Tn5 transposon mutagenesis. The mutants were found to be defective in cellular aggregation as well as in sporulation. Further phenotypic characterization indicated that the mutants were defective in social motility but normal in directed cell movements. Both mutations were cloned by a transposon-tagging method. Sequence analysis indicated that both insertions occurred in the same gene, which encodes a homolog of DnaK. Unlike the dnaK genes in other bacteria, this M. xanthus homolog appears not to be regulated by temperature or heat shock and is constitutively expressed during vegetative growth and under starvation. The defects of the mutants indicate that this DnaK homolog is important for the social motility and development of M. xanthus.

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