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 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.

scholarly journals Myxococcus xanthus as a Model Organism for Peptidoglycan Assembly and Bacterial Morphogenesis

2021 ◽  
Vol 9 (5) ◽  
pp. 916
Author(s):  
Huan Zhang ◽  
Srutha Venkatesan ◽  
Beiyan Nan
Keyword(s):  
De Novo ◽  
Myxococcus Xanthus ◽  
Model Organism ◽  
Life Stages ◽  
Negative Bacterium ◽  
Ideal Model ◽  
Daughter Cells ◽  
Bacterial Division ◽  
Cell Shapes ◽  
Rare Opportunity

A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis, because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.

scholarly journals Basal-Level Effects of (p)ppGpp in the Absence of Branched-Chain Amino Acids in Actinobacillus pleuropneumoniae

2020 ◽  
Vol 202 (8) ◽  
Author(s):  
Gang Li ◽  
Qian Zhao ◽  
Tian Luan ◽  
Yangbo Hu ◽  
Yueling Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
De Novo ◽  
Model Organism ◽  
Stringent Response ◽  
Actinobacillus Pleuropneumoniae ◽  
Branched Chain Amino Acids ◽  
Content Type ◽  
Phenotypic Differences ◽  
Branched Chain

ABSTRACT The (p)ppGpp-mediated stringent response (SR) is a highly conserved regulatory mechanism in bacterial pathogens, enabling adaptation to adverse environments, and is linked to pathogenesis. Actinobacillus pleuropneumoniae can cause damage to the lungs of pigs, its only known natural host. Pig lungs are known to have a low concentration of free branched-chain amino acids (BCAAs) compared to the level in plasma. We had investigated the role for (p)ppGpp in viability and biofilm formation of A. pleuropneumoniae. Now, we sought to determine whether (p)ppGpp was a trigger signal for the SR in A. pleuropneumoniae in the absence of BCAAs. Combining transcriptome and phenotypic analyses of the wild type (WT) and an relA spoT double mutant [which does not produce (p)ppGpp], we found that (p)ppGpp could repress de novo purine biosynthesis and activate antioxidant pathways. There was a positive correlation between GTP and endogenous hydrogen peroxide content. Furthermore, the growth, viability, morphology, and virulence were altered by the inability to produce (p)ppGpp. Genes involved in the biosynthesis of BCAAs were constitutively upregulated, regardless of the existence of BCAAs, without accumulation of (p)ppGpp beyond a basal level. Collectively, our study shows that the absence of BCAAs was not a sufficient signal to trigger the SR in A. pleuropneumoniae. (p)ppGpp-mediated regulation in A. pleuropneumoniae is different from that described for the model organism Escherichia coli. Further work will establish whether the (p)ppGpp-dependent SR mechanism in A. pleuropneumoniae is conserved among other veterinary pathogens, especially those in the Pasteurellaceae family. IMPORTANCE (p)ppGpp is a key player in reprogramming transcriptomes to respond to nutritional challenges. Here, we present transcriptional and phenotypic differences of A. pleuropneumoniae grown in different chemically defined media in the absence of (p)ppGpp. We show that the deprivation of branched-chain amino acids (BCAAs) does not elicit a change in the basal-level (p)ppGpp, but this level is sufficient to regulate the expression of BCAA biosynthesis. The mechanism found in A. pleuropneumoniae is different from that of the model organism Escherichia coli but similar to that found in some Gram-positive bacteria. This study not only broadens the research scope of (p)ppGpp but also further validates the complexity and multiplicity of (p)ppGpp regulation in microorganisms that occupy different biological niches.

scholarly journals A Novel Tool for the Generation of Conditional Knockouts To Study Gene Function across the Plasmodium falciparum Life Cycle

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Marta Tibúrcio ◽  
Annie S. P. Yang ◽  
Kazuhide Yahata ◽  
Pablo Suárez-Cortés ◽  
Hugo Belda ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Genetic Modification ◽  
Gene Deletion ◽  
Genetically Modify ◽  
Complex Life Cycle ◽  
Mosquito Vector ◽  
Parasite Line ◽  
Content Type ◽  
First Time

ABSTRACT Plasmodium falciparum has a complex life cycle that involves interaction with multiple tissues inside the human and mosquito hosts. Identification of essential genes at all different stages of the P. falciparum life cycle is urgently required for clinical development of tools for malaria control and eradication. However, the study of P. falciparum is limited by the inability to genetically modify the parasite throughout its life cycle with the currently available genetic tools. Here, we describe the detailed characterization of a new marker-free P. falciparum parasite line that expresses rapamycin-inducible Cre recombinase across the full life cycle. Using this parasite line, we were able to conditionally delete the essential invasion ligand AMA1 in three different developmental stages for the first time. We further confirm efficient gene deletion by targeting the nonessential kinase FIKK7.1. IMPORTANCE One of the major limitations in studying P. falciparum is that so far only asexual stages are amenable to rapid conditional genetic modification. The most promising drug targets and vaccine candidates, however, have been refractory to genetic modification because they are essential during the blood stage or for transmission in the mosquito vector. This leaves a major gap in our understanding of parasite proteins in most life cycle stages and hinders genetic validation of drug and vaccine targets. Here, we describe a method that supports conditional gene deletion across the P. falciparum life cycle for the first time. We demonstrate its potential by deleting essential and nonessential genes at different parasite stages, which opens up completely new avenues for the study of malaria and drug development. It may also allow the realization of novel vaccination strategies using attenuated parasites.

scholarly journals Distinct Prominent Roles for Enzymes of Plasmodium berghei Heme Biosynthesis in Sporozoite and Liver Stage Maturation

2016 ◽  
Vol 84 (11) ◽  
pp. 3252-3262 ◽  
Author(s):  
Zaira Rizopoulos ◽  
Kai Matuschewski ◽  
Joana M. Haussig
Keyword(s):  
Life Cycle ◽  
De Novo ◽  
Aminolevulinic Acid ◽  
Vital Role ◽  
Heme Biosynthesis ◽  
Cycle Progression ◽  
Liver Stage ◽  
Content Type ◽  
Targeted Gene Deletion ◽  
Complex Regulation

Malarial parasites have evolved complex regulation of heme supply and disposal to adjust to heme-rich and -deprived host environments. In addition to its own pathway for heme biosynthesis,Plasmodiumlikely harbors mechanisms for heme scavenging from host erythrocytes. Elaborate compartmentalization ofde novoheme synthesis into three subcellular locations, including the vestigial plastid organelle, indicates critical roles in life cycle progression. In this study, we systematically profile the essentiality of heme biosynthesis by targeted gene deletion of enzymes in early steps of this pathway. We show that disruption of endogenous heme biosynthesis leads to a first detectable defect in oocyst maturation and sporogony in theAnophelesvector, whereas blood stage propagation, colonization of mosquito midguts, or initiation of oocyst development occurs indistinguishably from that of wild-type parasites. Although sporozoites are produced by parasites lacking an intact pathway for heme biosynthesis, they are absent from mosquito salivary glands, indicative of a vital role for heme biosynthesis only in sporozoite maturation. Rescue of the first defect in sporogony permitted analysis of potential roles in liver stages. We show that liver stage parasites benefit from but do not strictly depend upon their own aminolevulinic acid synthase and that they can scavenge aminolevulinic acid from the host environment. Together, our experimental genetics analysis ofPlasmodiumenzymes for heme biosynthesis exemplifies remarkable shifts between the use of endogenous and host resources during life cycle progression.

scholarly journals Protein Prenylation and Hsp40 in Thermotolerance of Plasmodium falciparum Malaria Parasites

mBio ◽  
2021 ◽  
Author(s):  
Emily S. Mathews ◽  
Andrew J. Jezewski ◽  
Audrey R. Odom John
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Malaria Parasite ◽  
Plasmodium Falciparum Malaria ◽  
Complex Life Cycle ◽  
Large Temperature ◽  
Protein Prenylation ◽  
Content Type

During its complex life cycle, the malaria parasite survives dramatic environmental stresses, including large temperature shifts. Protein prenylation is required during asexual replication of Plasmodium falciparum , and the canonical heat shock protein 40 protein (HSP40; PF3D7_1437900) is posttranslationally modified with a 15-carbon farnesyl isoprenyl group.

scholarly journals Role of Two Metacaspases in Development and Pathogenicity of the Rice Blast Fungus Magnaporthe oryzae

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jessie Fernandez ◽  
Victor Lopez ◽  
Lisa Kinch ◽  
Mariel A. Pfeifer ◽  
Hillery Gray ◽  
...  
Keyword(s):  
Cell Death ◽  
Food Security ◽  
Life Cycle ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Complex Life Cycle ◽  
Content Type

ABSTRACT Rice blast disease caused by Magnaporthe oryzae is a devastating disease of cultivated rice worldwide. Infections by this fungus lead to a significant reduction in rice yields and threats to food security. To gain better insight into growth and cell death in M. oryzae during infection, we characterized two predicted M. oryzae metacaspase proteins, MoMca1 and MoMca2. These proteins appear to be functionally redundant and can complement the yeast Yca1 homologue. Biochemical analysis revealed that M. oryzae metacaspases exhibited Ca2+-dependent caspase activity in vitro. Deletion of both MoMca1 and MoMca2 in M. oryzae resulted in reduced sporulation, delay in conidial germination, and attenuation of disease severity. In addition, the double ΔMomca1mca2 mutant strain showed increased radial growth in the presence of oxidative stress. Interestingly, the ΔMomca1mca2 strain showed an increased accumulation of insoluble aggregates compared to the wild-type strain during vegetative growth. Our findings suggest that MoMca1 and MoMca2 promote the clearance of insoluble aggregates in M. oryzae, demonstrating the important role these metacaspases have in fungal protein homeostasis. Furthermore, these metacaspase proteins may play additional roles, like in regulating stress responses, that would help maintain the fitness of fungal cells required for host infection. IMPORTANCE Magnaporthe oryzae causes rice blast disease that threatens global food security by resulting in the severe loss of rice production every year. A tightly regulated life cycle allows M. oryzae to disarm the host plant immune system during its biotrophic stage before triggering plant cell death in its necrotrophic stage. The ways M. oryzae navigates its complex life cycle remain unclear. This work characterizes two metacaspase proteins with peptidase activity in M. oryzae that are shown to be involved in the regulation of fungal growth and development prior to infection by potentially helping maintain fungal fitness. This study provides new insights into the role of metacaspase proteins in filamentous fungi by illustrating the delays in M. oryzae morphogenesis in the absence of these proteins. Understanding the mechanisms by which M. oryzae morphology and development promote its devastating pathogenicity may lead to the emergence of proper methods for disease control.

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 Identification of a Putative Flavin Adenine Dinucleotide-Binding Monooxygenase as a Regulator for Myxococcus xanthus Development

2015 ◽  
Vol 197 (7) ◽  
pp. 1185-1196 ◽  
Author(s):  
Shanshan Cao ◽  
Miaomiao Wu ◽  
Shihui Xu ◽  
Xiuwen Yan ◽  
Xiaohua Mao
Keyword(s):  
Gene Cluster ◽  
Fruiting Body ◽  
Flavin Adenine Dinucleotide ◽  
Myxococcus Xanthus ◽  
Model Organism ◽  
Cell Aggregation ◽  
Developmental Cycle ◽  
Content Type ◽  
Induced Aggregation ◽  
Multicellular Morphogenesis

ABSTRACTGene clusters coding for the chaperone/usher (CU) pathway are widely distributed in many important environmental and pathogenic microbes; however, information about the regulatory machineries controlling CU gene expression during multicellular morphogenesis is missing. TheMyxococcus xanthusMcu system, encoded by themcuABCDgene cluster, represents a prototype of the archaic CU family that functions in spore coat formation. Using genome-wide transposon mutagenesis, we identified MXAN2872 to be a potential regulator of themcuABCoperon and demonstrated the necessity of MXAN2872 formcuABCexpression and fruiting body morphogenesis in early development.In silico, biochemical, and genetic analyses suggest that MXAN2872 encodes a Baeyer-Villiger monooxygenase (BVMO) of flavoproteins, and the potential cofactor-binding site as well as the BVMO fingerprint sequence is important for the regulatory role of the MXAN2872 protein. The expression profile ofmcuAin strains with an MXAN2872 deletion and point mutation agrees well with the timing of cell aggregation of these mutants. Furthermore, McuA could not be detected either in afruA-null mutant, where starvation-induced aggregation was completely blocked, or in the glycerol-induced spores, where sporulation was uncoupled from cell aggregation. In sum, the present work uncovers a positive role for MXAN2872, a metabolic enzyme-encoding gene, in controllingM. xanthusdevelopment. MXAN2872 functions by affecting the onset of cell aggregation, thereby leading to a secondary effect on the timing ofmcuABCexpression of this model organism.IMPORTANCEIdentification of the players that driveMyxococcus xanthusfruiting body formation is necessary for studying the mechanism of multicellular morphogenesis in this model organism. This study identifies MXAN2872, a gene encoding a putative flavin adenine dinucleotide-binding monooxygenase, to be a new interesting regulator regulating the timing of developmental aggregation. In addition, MXAN2872 seems to affect the expression of the chaperone/usher gene clustermcuin a manner that is aggregation dependent. Thus, in organisms characterized by a developmental cycle, expression of the chaperone/usher pathway can be controlled by morphological checkpoints, demonstrating another layer of complexity in the regulation of this conserved protein secretion pathway.

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.

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