Murein components rescue developmental sporulation of Myxococcus xanthus

1982 ◽  
Vol 152 (1) ◽  
pp. 462-470 ◽  
Author(s):  
L J Shimkets ◽  
D Kaiser
Keyword(s):  
Fruiting Body ◽  
High Cell Density ◽  
Myxococcus Xanthus ◽  
Sodium Dodecyl ◽  
Protein Composition ◽  
Diaminopimelic Acid ◽  
Nutrient Level ◽  
High Cell ◽  
Wild Type ◽  
Nutrient Rich Medium

Murein (peptidoglycan) components are able to rescue sporulation in certain sporulation-defective mutants of Myxococcus xanthus. N-Acetylglucosamine, N-acetylmuramic acid, diaminopimelic acid, and D-alanine each increase the number of spores produced by SpoC mutants. When all four components are included they have a synergistic effect, raising the number of spores produced by SpoC mutants to the wild-type level. Murein-rescued spores are resistant to heat and sonic oscillation and germinate when plated on a nutrient-rich medium. They appear to be identical to fruiting body spores in their ultrastructure, in their protein composition, and in their resistance to boiling sodium dodecyl sulfate. Murein rescue of sporulation, like fruiting body sporulation, requires high cell density, a low nutrient level, and a solid surface.

scholarly journals Myxococcus xanthus sasN Encodes a Regulator That Prevents Developmental Gene Expression during Growth

1998 ◽  
Vol 180 (23) ◽  
pp. 6215-6223 ◽  
Author(s):  
Di Xu ◽  
Chun Yang ◽  
Heidi B. Kaplan
Keyword(s):  
Cell Density ◽  
Fruiting Body ◽  
Growth And Development ◽  
High Cell Density ◽  
Myxococcus Xanthus ◽  
High Cell ◽  
Wild Type ◽  
Hydrophobic Region ◽  
Body Development ◽  
Fruiting Body Development

ABSTRACT Myxococcus xanthus multicellular fruiting body development is initiated by nutrient limitation at high cell density. Five clustered point mutations (sasB5, -14, -15, -16, and -17) can bypass the starvation and high-cell-density requirements for expression of the4521 developmental reporter gene. These mutants express4521 at high levels during growth and development in anasgB background, which is defective in generation of the cell density signal, A signal. A 1.3-kb region of the sasBlocus cloned from the wild-type chromosome restored the SasB+ phenotype to the five mutants. DNA sequence analysis of the 1.3-kb region predicted an open reading frame, designated SasN. The N terminus of SasN appears to contain a strongly hydrophobic region and a leucine zipper motif. SasN showed no significant sequence similarities to known proteins. A strain containing a newly constructedsasN-null mutation and Ω4521 Tn5lac in an otherwise wild-type background expressed 4521 at a high level during growth and development. A similar sasN-null mutant formed abnormal fruiting bodies and sporulated at about 10% the level of wild type. These data indicate that the wild-typesasN gene product is necessary for normal M. xanthus fruiting body development and functions as a critical regulator that prevents 4521 expression during growth.

scholarly journals Identification of Major Sporulation Proteins of Myxococcus xanthus Using a Proteomic Approach

2007 ◽  
Vol 189 (8) ◽  
pp. 3187-3197 ◽  
Author(s):  
John L. Dahl ◽  
Farah K. Tengra ◽  
David Dutton ◽  
Jinyuan Yan ◽  
Tracy M. Andacht ◽  
...  
Keyword(s):  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
Sodium Dodecyl ◽  
Protein S ◽  
Differentially Expressed ◽  
Insertion Mutagenesis ◽  
Wild Type ◽  
Proteomic Approach ◽  
Mutant Strains ◽  
Genes Encoding

ABSTRACT Myxococcus xanthus is a soil-dwelling, gram-negative bacterium that during nutrient deprivation is capable of undergoing morphogenesis from a vegetative rod to a spherical, stress-resistant spore inside a domed-shaped, multicellular fruiting body. To identify proteins required for building stress-resistant M. xanthus spores, we compared the proteome of liquid-grown vegetative cells with the proteome of mature fruiting body spores. Two proteins, protein S and protein S1, were differentially expressed in spores, as has been reported previously. In addition, we identified three previously uncharacterized proteins that are differentially expressed in spores and that exhibit no homology to known proteins. The genes encoding these three novel major spore proteins (mspA, mspB, and mspC) were inactivated by insertion mutagenesis, and the development of the resulting mutant strains was characterized. All three mutants were capable of aggregating, but for two of the strains the resulting fruiting bodies remained flattened mounds of cells. The most pronounced structural defect of spores produced by all three mutants was an altered cortex layer. We found that mspA and mspB mutant spores were more sensitive specifically to heat and sodium dodecyl sulfate than wild-type spores, while mspC mutant spores were more sensitive to all stress treatments examined. Hence, the products of mspA, mspB, and mspC play significant roles in morphogenesis of M. xanthus spores and in the ability of spores to survive environmental stress.

scholarly journals act Operon Control of Developmental Gene Expression in Myxococcus xanthus

2002 ◽  
Vol 184 (4) ◽  
pp. 1172-1179 ◽  
Author(s):  
Thomas M. A. Gronewold ◽  
Dale Kaiser
Keyword(s):  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
The Other ◽  
Loss Of Function ◽  
Wild Type ◽  
Developmental Gene ◽  
Developmental Gene Expression ◽  
Mutant Strains ◽  
Genes Encoding ◽  
Signal Production

ABSTRACT Cell-bound C-signal guides the building of a fruiting body and triggers the differentiation of myxospores. Earlier work has shown that transcription of the csgA gene, which encodes the C-signal, is directed by four genes of the act operon. To see how expression of the genes encoding components of the aggregation and sporulation processes depends on C-signaling, mutants with loss-of-function mutations in each of the act genes were investigated. These mutations were found to have no effect on genes that are normally expressed up to 3 h into development and are C-signal independent. Neither the time of first expression nor the rate of expression increase was changed in actA, actB, actC, or actD mutant strains. Also, there was no effect on A-signal production, which normally starts before 3 h. By contrast, the null act mutants have striking defects in C-signal production. These mutations changed the expression of four gene reporters that are related to aggregation and sporulation and are expressed at 6 h or later in development. The actA and actB null mutations substantially decreased the expression of all these reporters. The other act null mutations caused either premature expression to wild-type levels (actC) or delayed expression (actD), which ultimately rose to wild-type levels. The pattern of effects on these reporters shows how the C-signal differentially regulates the steps that together build a fruiting body and differentiate spores within it.

scholarly journals Proteins Associated with the Myxococcus xanthus Extracellular Matrix

2007 ◽  
Vol 189 (21) ◽  
pp. 7634-7642 ◽  
Author(s):  
Patrick D. Curtis ◽  
James Atwood ◽  
Ron Orlando ◽  
Lawrence J. Shimkets
Keyword(s):  
Extracellular Matrix ◽  
Biofilm Formation ◽  
Myxococcus Xanthus ◽  
Sodium Dodecyl ◽  
Wild Type ◽  
Fruiting Body Formation ◽  
Ecm Proteins ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
In The Wild

ABSTRACT Fruiting body formation of Myxococcus xanthus, like biofilm formation of many other organisms, involves the production of an extracellular matrix (ECM). While the polysaccharide component has been studied, the protein component has been largely unexplored. Proteins associated with the ECM were solubilized from purified ECM by boiling with sodium dodecyl sulfate and were identified by liquid chromatography-tandem mass spectrometry of tryptic fragments. The ECM is enriched in proteins of novel function; putative functions were assigned for only 5 of the 21 proteins. Thirteen putative ECM proteins had lipoprotein secretion signals. The genes for many ECM proteins were disrupted in the wild-type (WT), fibA, and pilA backgrounds. Disruption of the MXAN4860 gene had no effect in the WT or fibA background but in the pilA background resulted in a 24-h delay in aggregation and sporulation compared to its parent. The results of this study show that the M. xanthus ECM proteome is diverse and novel.

scholarly journals Chlamydomonas flagellar mutants lacking radial spokes and central tubules. Structure, composition, and function of specific axonemal components.

1978 ◽  
Vol 76 (3) ◽  
pp. 729-747 ◽  
Author(s):  
G B Witman ◽  
J Plummer ◽  
G Sander
Keyword(s):  
Lattice Spacing ◽  
Sodium Dodecyl ◽  
Internal Standard ◽  
Protein Composition ◽  
Wild Type ◽  
Microscope Examination ◽  
Radial Spokes ◽  
Dynein Arms ◽  
High Molecular Weight Proteins ◽  
And Function

The fine structure, protein composition, and roles in flagellar movement of specific axonemal components were studied in wild-type Chlamydomonas and paralyzed mutants pf-14, pf-15A, and pf-19. Electron microscope examination of the isolated axoneme of pf-14 showed that it lacks the radial spokes but is otherwise structurally normal. Comparison of isolated axonemes of wild type and pf-14 by sodium dodecyl sulfate-acrylamide gel electrophoresis indicated that the mutant is missing a protein of 118,000 mol wt; this protein is apparently a major component of the spokes. Pf-15A and pf-19 lack the central tubules and sheath; axonemes of these mutants are missing three high molecular weight proteins which are probably components of the central tubule-central sheath complex. Under conditions where wild-type axonemes reactivated, axonemes of the three mutants remained intact but did not form bends. However, mutant and wild-type axonemes underwent identical adenosine triphosphate-induced disintegration after treatment with trypsin; the dynein arms of the mutants are therefore capable of generating interdoublet shearing forces. These findings indicated that both the radial spokes and the central tubule-central sheath complex are essential for conversion of interdoublet sliding into axonemal bending. Moreover, because axonemes of pf-14 remained intact under reactivating conditions, the nexin links alone are sufficient to limit the amount of interdoublet sliding that occurs. The axial periodicities of the central sheath, dynein arms, radial spokes, and nexin links of Chlamydomonas were determined by electron microscopy using the lattice-spacing of crystalline catalase as an internal standard. Some new ultrastructural details of the components are described.

scholarly journals Two Lipid Signals Guide Fruiting Body Development of Myxococcus xanthus

mBio ◽  
2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Swapna Bhat ◽  
Tilman Ahrendt ◽  
Christina Dauth ◽  
Helge B. Bode ◽  
Lawrence J. Shimkets
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
Chain Fatty Acid ◽  
Fatty Alcohols ◽  
Lipid Bodies ◽  
Wild Type ◽  
Bioactive Lipids ◽  
Content Type

ABSTRACTMyxococcus xanthusproduces several extracellular signals that guide fruiting body morphogenesis and spore differentiation. Mutants defective in producing a signal may be rescued by codevelopment with wild-type cells or cell fractions containing the signal. In this paper, we identify two molecules that rescue development of the E signal-deficient mutant LS1191 at physiological concentrations,iso15:0 branched-chain fatty acid (FA) and 1-iso15:0-alkyl-2,3-di-iso15:0-acyl glycerol (TG1), a development-specific monoalkyl-diacylglycerol. The physiological concentrations of the bioactive lipids were determined by mass spectrometry from developing wild-type cells using chemically synthesized standards. Synthetic TG1 restored fruiting body morphogenesis and sporulation and activated the expression of the developmentally regulated gene with locus tagMXAN_2146at physiological concentrations, unlike its nearly identical tri-iso15:0 triacylglycerol (TAG) counterpart, which has an ester linkage instead of an ether linkage.iso15:0 FA restored development at physiological concentrations, unlike palmitic acid, a straight-chain fatty acid. The addition of either lipid stimulates cell shortening, with an 87% decline in membrane surface area, concomitantly with the production of lipid bodies at each cell pole and in the center of the cell. We suggest that cells produce triacylglycerol from membrane phospholipids. Bioactive lipids may be released byprogrammedcelldeath (PCD), which claims up to 80% of developing cells, since cells undergoing PCD produce lipid bodies before lysing.IMPORTANCELike mammalian adipose tissue, many of theM. xanthuslipid body lipids are triacylglycerols (TAGs), containing ester-linked fatty acids. In both systems, ester-linked fatty acids are retrieved from TAGs with lipases and consumed by the fatty acid degradation cycle. Both mammals andM. xanthusalso produce lipids containing ether-linked fatty alcohols with alkyl or vinyl linkages, such as plasmalogens. Alkyl and vinyl linkages are not hydrolyzed by lipases, and no clear role has emerged for lipids bearing them. For example, plasmalogen deficiency in mice has detrimental consequences to spermatocyte development, myelination, axonal survival, eye development, and long-term survival, though the precise reasons remain elusive. Lipids containing alkyl- and vinyl-linked fatty alcohols are development-specific products inM. xanthus. Here, we show that one of them rescues the development of E signal-producing mutants at physiological concentrations.

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 Developmental Aggregation of Myxococcus xanthus Requires frgA, anfrz-Related Gene

2000 ◽  
Vol 182 (23) ◽  
pp. 6614-6621 ◽  
Author(s):  
Kyungyun Cho ◽  
Anke Treuner-Lange ◽  
Kathleen A. O'Connor ◽  
David R. Zusman
Keyword(s):  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
Complex Life Cycle ◽  
Fruiting Bodies ◽  
Related Gene ◽  
Wild Type ◽  
Fruiting Body Formation ◽  
Body Formation ◽  
Extracellular Signals ◽  
Directed Motility

ABSTRACT Myxococcus xanthus is a gram-negative bacterium which has a complex life cycle that includes multicellular fruiting body formation. Frizzy mutants are characterized by the formation of tangled filaments instead of hemispherical fruiting bodies on fruiting agar. Mutations in the frz genes have been shown to cause defects in directed motility, which is essential for both vegetative swarming and fruiting body formation. In this paper, we report the discovery of a new gene, called frgA (forfrz-related gene), which confers a subset of the frizzy phenotype when mutated. The frgA null mutant showed reduced swarming and the formation of frizzy aggregates on fruiting agar. However, this mutant still displayed directed motility in a spatial chemotaxis assay, whereas the majority offrz mutants fail to show directed movements in this assay. Furthermore, the frizzy phenotype of the frgA mutant could be complemented extracellularly by wild-type cells or strains carrying non-frz mutations. The phenotype of the frgAmutant is similar to that of the abcA mutant and suggests that both of these mutants could be defective in the production or export of extracellular signals required for fruiting body formation rather than in the sensing of such extracellular signals. ThefrgA gene encodes a large protein of 883 amino acids which lacks homologues in the databases. The frgA gene is part of an operon which includes two additional genes, frgBand frgC. The frgB gene encodes a putative histidine protein kinase, and the frgC gene encodes a putative response regulator. The frgB and frgCnull mutants, however, formed wild-type fruiting bodies.

scholarly journals Non-canonical localization of RubisCO under high light conditions in the toxic cyanobacteriumMicrocystis aeruginosaPCC7806

2019 ◽  
Author(s):  
Tino Barchewitz ◽  
Arthur Guljamow ◽  
Sven Meissner ◽  
Stefan Timm ◽  
Manja Henneberg ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Cytoplasmic Membrane ◽  
High Cell Density ◽  
High Light ◽  
Membrane Association ◽  
High Cell ◽  
Light Conditions ◽  
Wild Type ◽  
Electron Microscopic ◽  
Steady State Levels

AbstractThe frequent production of the hepatotoxin microcystin and its impact on the life-style of bloom-forming cyanobacteria are poorly understood. Here we report that microcystin interferes with the assembly and the subcellular localization of RubisCO, inMicrocystis aeruginosaPCC7806. Immunofluorescence, electron microscopic and cellular fractionation studies revealed a pronounced heterogeneity in the subcellular localization of RubisCO. At high cell density, RubisCO particles are largely separate from carboxysomes inM. aeruginosaand relocate to the cytoplasmic membrane under high-light conditions. We hypothesize that the binding of microcystin to RubisCO promotes its membrane association and enables an extreme versatility of the enzyme. Steady-state levels of the RubisCO CO2fixation product 3-phosphoglycerate are significantly higher in the microcystin-producing wild type. We also detected noticeable amounts of the RubisCO oxygenase reaction product secreted into the medium that may support the mutual interaction ofM. aeruginosawith its heterotrophic microbial community.

scholarly journals Reduced Levels of ATF-2 Predispose Mice to Mammary Tumors

2006 ◽  
Vol 27 (5) ◽  
pp. 1730-1744 ◽  
Author(s):  
Toshio Maekawa ◽  
Toshie Shinagawa ◽  
Yuji Sano ◽  
Takahiko Sakuma ◽  
Shintaro Nomura ◽  
...  
Keyword(s):  
Cell Density ◽  
Target Genes ◽  
High Cell Density ◽  
Critical Role ◽  
Susceptibility Gene ◽  
Mammary Tumors ◽  
Mrna Levels ◽  
High Cell ◽  
Wild Type ◽  
Induced Apoptosis

ABSTRACT Transcription factor ATF-2 is a nuclear target of stress-activated protein kinases, such as p38, which are activated by various extracellular stresses, including UV light. Here, we show that ATF-2 plays a critical role in hypoxia- and high-cell-density-induced apoptosis and the development of mammary tumors. Compared to wild-type cells, Atf-2 −/− mouse embryonic fibroblasts (MEFs) were more resistant to hypoxia- and anisomycin-induced apoptosis but remained equally susceptible to other stresses, including UV. Atf-2 −/− and Atf-2 +/− MEFs could not express a group of genes, such as Gadd45α, whose overexpression can induce apoptosis, in response to hypoxia. Atf-2 −/− MEFs also had a higher saturation density than wild-type cells and expressed lower levels of Maspin, the breast cancer tumor suppressor, which is also known to enhance cellular sensitivity to apoptotic stimuli. Atf-2 −/− MEFs underwent a lower degree of apoptosis at high cell density than wild-type cells. Atf-2 +/− mice were highly prone to mammary tumors that expressed reduced levels of Gadd45α and Maspin. The ATF-2 mRNA levels in human breast cancers were lower than those in normal breast tissue. Thus, ATF-2 acts as a tumor susceptibility gene of mammary tumors, at least partly, by activating a group of target genes, including Maspin and Gadd45α.

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