scholarly journals Phage Reduce Stability for Regaining Infectivity during Antagonistic Coevolution with Host Bacterium

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 118 ◽  
Author(s):  
Yihui Yuan ◽  
Qin Peng ◽  
Shaowen Zhang ◽  
Tingting Liu ◽  
Shuo Yang ◽  
...  
Keyword(s):  
First Generation ◽  
Transmembrane Domain ◽  
Polymorphism Analysis ◽  
Host Bacterium ◽  
Cell Wall Polysaccharide ◽  
Wild Type ◽  
Associated Proteins ◽  
In The Wild ◽  
Bacterial Mutants ◽  
Type Phage

The coevolution between phage and host bacterium is an important force that drives the evolution of the microbial community, yet the coevolution mechanisms have still not been well analyzed. Here, by analyzing the interaction between a Bacillus phage vB_BthS_BMBphi and its host bacterium, the coevolution mechanisms of the first-generation phage-resistant bacterial mutants and regained-infectivity phage mutants were studied. The phage-resistant bacterial mutants showed several conserved mutations as a potential reason for acquiring phage resistance, including the mutation in flagellum synthesis protein FlhA and cell wall polysaccharide synthesis protein DltC. All the phage-resistant bacterial mutants showed a deleted first transmembrane domain of the flagellum synthesis protein FlhA. Meanwhile, the regain-infectivity phage mutants all contained mutations in three baseplate-associated phage tail proteins by one nucleotide, respectively. A polymorphism analysis of the three mutant nucleotides in the wild-type phage revealed that the mutations existed before the interaction of the phage and the bacterium, while the wild-type phage could not infect the phage-resistant bacterial mutants, which might be because the synchronized mutations of the three nucleotides were essential for regaining infectivity. This study for the first time revealed that the synergism mutation of three phage baseplate-associated proteins were essential for the phages’ regained infectivity. Although the phage mutants regained infectivity, their storage stability was decreased and the infectivity against the phage-resistant bacterial mutants was reduced, suggesting the phage realized the continuation of the species by way of “dying to survive”.

scholarly journals Replacement of both tryptophan residues at 388 and 412 completely abolished cytochalasin B photolabelling of the GLUT1 glucose transporter

1994 ◽  
Vol 302 (2) ◽  
pp. 355-361 ◽  
Author(s):  
K Inukai ◽  
T Asano ◽  
H Katagiri ◽  
M Anai ◽  
M Funaki ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Cytochalasin B ◽  
Transmembrane Domain ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Site Directed Mutagenesis ◽  
Transport Activity ◽  
Wild Type ◽  
In The Wild ◽  
Glut1 Glucose Transporter

A mutated GLUT1 glucose transporter, a Trp-388, 412 mutant whose tryptophans 388 and 412 were both replaced by leucines, was constructed by site-directed mutagenesis and expressed in Chinese hamster ovary cells. Glucose transport activity was decreased to approx. 30% in the Trp-388, 412 mutant compared with that in the wild type, a similar decrease in transport activity had been observed previously in the Trp-388 mutant and the Trp-412 mutant which had leucine at 388 and 412 respectively. Cytochalasin B labelling of the Trp-388 mutant was only decreased rather than abolished, a result similar to that obtained previously for the Trp-412 mutant. Cytochalasin B labelling was finally abolished completely in the Trp-388, 412 mutant, while cytochalasin B binding to this mutant was decreased to approx. 30% of that of the wild-type GLUT1 at the concentration used for photolabelling. This level of binding is thought to be adequate to detect labelling, assuming that the labelling efficiency of these transporters is similar. These findings suggest that cytochalasin B binds to the transmembrane domain of the glucose transporter in the vicinity of helix 10-11, and is inserted covalently by photoactivation at either the 388 or the 412 site.

scholarly journals The abnormal oocyte phenotype is correlated with the presence of blood transposon in Drosophila melanogaster.

Genetics ◽  
1989 ◽  
Vol 123 (3) ◽  
pp. 485-494
Author(s):  
G Lavorgna ◽  
C Malva ◽  
A Manzi ◽  
S Gigliotti ◽  
F Graziani
Keyword(s):  
Drosophila Melanogaster ◽  
Sequence Analysis ◽  
Restriction Enzyme ◽  
Polymorphism Analysis ◽  
Restriction Map ◽  
Dna Rearrangement ◽  
Restriction Enzyme Site ◽  
Wild Type ◽  
Chromosome Walking ◽  
In The Wild

Abstract The abnormal oocyte mutation (2;44) originates in the wild: it confers no visible phenotype on homozygous abo males or females, but homozygous abo females produce defective eggs and the probability of their developing into adults is much lower than that of heterozygous sister females. We isolated by chromosome walking 200 kb of DNA from region 32. This paper reports that a restriction enzyme site polymorphism analysis in wild type and mutant stocks allowed us to identify a DNA rearrangement present only in stocks carrying the abo mutation. The rearrangement is caused by a DNA insert on the abo chromosome in region 32E which, by restriction map and sequence analysis, was identified as copia-like blood transposon. The transposon, in strains that had remained in abo homozygous conditions for several generations and had lost the abo maternal-effect, was no longer present in region 32E. Certain features of the abo mutation, discussed in the light of this finding, may be ascribed to the nature of the particular allele studied.

scholarly journals Complexome profiling on the lpa2 mutant reveals insights into PSII biogenesis and new PSII associated proteins

2021 ◽  
Author(s):  
Benjamin Spaniol ◽  
Julia Lang ◽  
Benedikt Venn ◽  
Lara Schake ◽  
Frederik K Sommer ◽  
...  
Keyword(s):  
Complex Dynamics ◽  
Oxygen Evolving Complex ◽  
Cytochrome B6f Complex ◽  
Wild Type ◽  
Low Light ◽  
Chlorophyll Breakdown ◽  
Associated Proteins ◽  
In The Wild ◽  
Oxygen Evolving ◽  
B6f Complex

We have identified the homolog of LOW PSII ACCUMULATION 2 (LPA2) in Chlamydomonas. A Chlamydomonas lpa2 mutant grew slower in low light and was hypersensitive to high light. PSII maximum quantum efficiency was reduced by 38%. Synthesis and stability of newly made PSII core subunits D1, D2, CP43, and CP47 were not impaired. Complexome profiling revealed that in the mutant CP43 was reduced to ~23%, D1, D2, and CP47 to ~30% of wild-type levels, while small PSII core subunits and components of the oxygen evolving complex were reduced at most by factor two. PSII supercomplexes, dimers, and monomers were reduced to 7%, 26%, and 60% of wild-type levels, while RC47 was increased ~6-fold. Our data indicate that LPA2 acts at a step during PSII assembly without which PSII monomers and especially further assemblies become intrinsically unstable and prone to degradation. Levels of ATP synthase and LHCII were 29% and 27% higher in the mutant than in the wild type, whereas levels of the cytochrome b6f complex were unaltered. While the abundance of PSI core subunits and antennae hardly changed, LHCI antennae were more disconnected in the lpa2 mutant, presumably as an adaptive response to reduce excitation of PSI. The disconnection of LHCA2,9 together with PSAH and PSAG was the prime response, but independent and additional disconnection of LHCA1,3-8 along with PSAK occurred as well. Finally, based on co-migration profiles, we identified three novel putative PSII associated proteins with potential roles in regulating PSII complex dynamics, assembly, and chlorophyll breakdown.

scholarly journals A Chlamydomonas outer arm dynein mutant missing the alpha heavy chain.

1991 ◽  
Vol 113 (3) ◽  
pp. 615-622 ◽  
Author(s):  
H Sakakibara ◽  
D R Mitchell ◽  
R Kamiya
Keyword(s):  
Cross Section ◽  
Heavy Chain ◽  
Fragment Length Polymorphism ◽  
Beat Frequency ◽  
Polymorphism Analysis ◽  
Wild Type ◽  
Heavy Chains ◽  
Flagellar Beat ◽  
Section Electron ◽  
In The Wild

A novel Chlamydomonas flagellar mutant (oda-11) missing the alpha heavy chain of outer arm dynein but retaining the beta and gamma heavy chains was isolated. Restriction fragment length polymorphism analysis with an alpha heavy chain locus genomic probe indicated that the oda-11 mutation was genetically linked with the structural gene of the alpha heavy chain. In cross-section electron micrographs, the oda-11 axoneme lacked the outermost appendage of the outer arm, indicating that the alpha heavy chain should be located in this region in the wild-type outer arm. This mutant swam at 119 microns/s at 25 degrees C, i.e., at an intermediate speed between those of wild type (194 microns/s) and of oda-1 (62 microns/s), a mutant missing the entire outer dynein arm. The flagellar beat frequency (approximately 50 Hz) was also between those of wild type (approximately 60 Hz) and oda-1 (approximately 26 Hz). These results indicate that the outer dynein arm of Chlamydomonas can be assembled without the alpha heavy chain, and that the outer arm missing the alpha heavy chain retains partial function.

scholarly journals Characterization of Regulatory Pathways in Xylella fastidiosa: Genes and Phenotypes Controlled by algU

2007 ◽  
Vol 73 (21) ◽  
pp. 6748-6756 ◽  
Author(s):  
Xiang Yang Shi ◽  
C. Korsi Dumenyo ◽  
Rufina Hernandez-Martinez ◽  
Hamid Azad ◽  
Donald A. Cooksey
Keyword(s):  
Microarray Analysis ◽  
Biofilm Formation ◽  
Xylella Fastidiosa ◽  
Bacterial Pathogens ◽  
Regulatory Gene ◽  
Cell Aggregation ◽  
Wild Type ◽  
Regulatory Pathways ◽  
In The Wild ◽  
Bacterial Mutants

ABSTRACT Many virulence genes in plant bacterial pathogens are coordinately regulated by “global” regulatory genes. Conducting DNA microarray analysis of bacterial mutants of such genes, compared with the wild type, can help to refine the list of genes that may contribute to virulence in bacterial pathogens. The regulatory gene algU, with roles in stress response and regulation of the biosynthesis of the exopolysaccharide alginate in Pseudomonas aeruginosa and many other bacteria, has been extensively studied. The role of algU in Xylella fastidiosa, the cause of Pierce's disease of grapevines, was analyzed by mutation and whole-genome microarray analysis to define its involvement in aggregation, biofilm formation, and virulence. In this study, an algU::nptII mutant had reduced cell-cell aggregation, attachment, and biofilm formation and lower virulence in grapevines. Microarray analysis showed that 42 genes had significantly lower expression in the algU::nptII mutant than in the wild type. Among these are several genes that could contribute to cell aggregation and biofilm formation, as well as other physiological processes such as virulence, competition, and survival.

scholarly journals His20 Provides the Sole Functionally Significant Side Chain in the Essential TonB Transmembrane Domain

2007 ◽  
Vol 189 (7) ◽  
pp. 2825-2833 ◽  
Author(s):  
Ray A. Larsen ◽  
Gail E. Deckert ◽  
Kyle A. Kastead ◽  
Surendranathan Devanathan ◽  
Kimberly L. Keller ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Cytoplasmic Membrane ◽  
Transmembrane Domain ◽  
Protonmotive Force ◽  
Wild Type ◽  
Carboxy Terminus ◽  
Amino Terminal ◽  
In The Wild ◽  
Mutant Phenotypes

ABSTRACT The cytoplasmic membrane protein TonB couples the protonmotive force of the cytoplasmic membrane to active transport across the outer membrane of Escherichia coli. The uncleaved amino-terminal signal anchor transmembrane domain (TMD; residues 12 to 32) of TonB and the integral cytoplasmic membrane proteins ExbB and ExbD are essential to this process, with important interactions occurring among the several TMDs of all three proteins. Here, we show that, of all the residues in the TonB TMD, only His20 is essential for TonB activity. When alanyl residues replaced all TMD residues except Ser16 and His20, the resultant “all-Ala Ser16 His20” TMD TonB retained 90% of wild-type iron transport activity. Ser16Ala in the context of a wild-type TonB TMD was fully active. In contrast, His20Ala in the wild-type TMD was entirely inactive. In more mechanistically informative assays, the all-Ala Ser16 His20 TMD TonB unexpectedly failed to support formation of disulfide-linked dimers by TonB derivatives bearing Cys substitutions for the aromatic residues in the carboxy terminus. We hypothesize that, because ExbB/D apparently cannot efficiently down-regulate conformational changes at the TonB carboxy terminus through the all-Ala Ser16 His20 TMD, the TonB carboxy terminus might fold so rapidly that disulfide-linked dimers cannot be efficiently trapped. In formaldehyde cross-linking experiments, the all-Ala Ser16 His20 TMD also supported large numbers of apparently nonspecific contacts with unknown proteins. The all-Ala Ser16 His20 TMD TonB retained its dependence on ExbB/D. Together, these results suggest that a role for ExbB/D might be to control rapid and nonspecific folding that the unregulated TonB carboxy terminus otherwise undergoes. Such a model helps to reconcile the crystal/nuclear magnetic resonance structures of the TonB carboxy terminus with conformational changes and mutant phenotypes observed at the TonB carboxy terminus in vivo.

scholarly journals Importance of Angomonas deanei KAP4 for kDNA arrangement, cell division and maintenance of the host-bacterium relationship

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Camila Silva Gonçalves ◽  
Carolina Moura Costa Catta-Preta ◽  
Bruno Repolês ◽  
Jeremy C. Mottram ◽  
Wanderley De Souza ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Symbiotic Bacterium ◽  
Host Bacterium ◽  
Mitochondrial Enzymes ◽  
Wild Type ◽  
Dna Damage And Repair ◽  
Cell Structures ◽  
Repair Mechanisms ◽  
Associated Proteins ◽  
Mutualistic Relationship

AbstractAngomonas deanei coevolves in a mutualistic relationship with a symbiotic bacterium that divides in synchronicity with other host cell structures. Trypanosomatid mitochondrial DNA is contained in the kinetoplast and is composed of thousands of interlocked DNA circles (kDNA). The arrangement of kDNA is related to the presence of histone-like proteins, known as KAPs (kinetoplast-associated proteins), that neutralize the negatively charged kDNA, thereby affecting the activity of mitochondrial enzymes involved in replication, transcription and repair. In this study, CRISPR-Cas9 was used to delete both alleles of the A. deanei KAP4 gene. Gene-deficient mutants exhibited high compaction of the kDNA network and displayed atypical phenotypes, such as the appearance of a filamentous symbionts, cells containing two nuclei and one kinetoplast, and division blocks. Treatment with cisplatin and UV showed that Δkap4 null mutants were not more sensitive to DNA damage and repair than wild-type cells. Notably, lesions caused by these genotoxic agents in the mitochondrial DNA could be repaired, suggesting that the kDNA in the kinetoplast of trypanosomatids has unique repair mechanisms. Taken together, our data indicate that although KAP4 is not an essential protein, it plays important roles in kDNA arrangement and replication, as well as in the maintenance of symbiosis.

scholarly journals Functional Nonequivalency of Actin Isovariants inArabidopsis

2002 ◽  
Vol 13 (1) ◽  
pp. 251-261 ◽  
Author(s):  
Muthugapatti K. Kandasamy ◽  
Elizabeth C. McKinney ◽  
Richard B. Meagher
Keyword(s):  
Actin Filaments ◽  
Normal Development ◽  
Regulatory Sequences ◽  
Actin Gene ◽  
Direct Proportion ◽  
Wild Type ◽  
Vegetative Tissues ◽  
Associated Proteins ◽  
In The Wild ◽  
Insight Into

Plants encode at least two ancient and divergent classes of actin, reproductive and vegetative, and each class produces several subclasses of actin isovariants. To gain insight into the functional significance of the actin isovariants, we generated transgenicArabidopsis lines that expressed a reproductive actin, ACT1, under the control of the regulatory sequences of a vegetative actin gene, ACT2. In the wild-type plants, ACT1 is predominantly expressed in the mature pollen, growing pollen tubes, and ovules, whereas ACT2 is constitutively and strongly expressed in all vegetative tissues and organs, but not in pollen. Misexpression of ACT1 in vegetative tissues causes dwarfing of plants and altered morphology of most organs, and the effects are in direct proportion to protein expression levels. Similar overexpression of ACT2 has little effect. Immunolocalization of actin in leaf cells from transgenic plants with highest levels of ACT1 protein revealed massive polymerization, bundling, and reorganization of actin filaments. This phenomenon suggests that misexpression of ACT1 isovariant in vegetative tissues affects the dynamics of actin and actin-associated proteins, in turn disrupting the organization of actin cytoskeleton and normal development of plants.

scholarly journals Activation and Transfer of the Chromosomal Phage Resistance Mechanism AbiV in Lactococcus lactis

2009 ◽  
Vol 75 (10) ◽  
pp. 3358-3361 ◽  
Author(s):  
Jakob Haaber ◽  
Sylvain Moineau ◽  
Karin Hammer
Keyword(s):  
Reverse Transcriptase ◽  
Lactococcus Lactis ◽  
Resistance Mechanism ◽  
Upstream Region ◽  
Phage Resistance ◽  
Wild Type ◽  
First Report ◽  
In The Wild ◽  
Resistant Mutants ◽  
Type Phage

ABSTRACT AbiV is a chromosomally encoded phage resistance mechanism that is silent in the wild-type phage-sensitive strain Lactococcus lactis subsp. cremoris MG1363. Spontaneous phage-resistant mutants of L. lactis MG1363 were analyzed by reverse transcriptase PCR and shown to express AbiV. This expression was related to a reorganization in the upstream region of abiV. Transfer of abiV between two lactococcal strains, most likely by conjugation, was also demonstrated. To our knowledge, this is the first report of natural transfer of a chromosomally encoded phage resistance mechanism.

scholarly journals Galactosylation of the Secondary Cell Wall Polysaccharide ofBacillus anthracisand Its Contribution to Anthrax Pathogenesis

2017 ◽  
Vol 200 (5) ◽  
Author(s):  
Alice Chateau ◽  
Justin Mark Lunderberg ◽  
So Young Oh ◽  
Teresa Abshire ◽  
Arthur Friedlander ◽  
...  
Keyword(s):  
Cell Wall ◽  
Glutamic Acid ◽  
Bacillus Anthracis ◽  
Secondary Cell Wall ◽  
Cell Wall Polysaccharide ◽  
Wild Type ◽  
Content Type ◽  
Bacterial Inoculum ◽  
Associated Proteins

ABSTRACTBacillus anthracis, the causative agent of anthrax disease, elaborates a secondary cell wall polysaccharide (SCWP) that is essential for bacterial growth and cell division.B. anthracisSCWP is comprised of trisaccharide repeats with the structure, [→4)-β-ManNAc-(1→4)-β-GlcNAc(O3-α-Gal)-(1→6)-α-GlcNAc(O3-α-Gal,O4-β-Gal)-(1→]6-12. The genes whose products promote the galactosylation ofB. anthracisSCWP are not yet known. We show here that the expression ofgalE1, encoding a UDP-glucose 4-epimerase necessary for the synthesis of UDP-galactose, is required forB. anthracisSCWP galactosylation. ThegalE1mutant assembles surface (S) layer and S layer-associated proteins that associate with ketal-pyruvylated SCWP via their S layer homology domains similarly to wild-typeB. anthracis, but the mutant displays a defect in γ-phage murein hydrolase binding to SCWP. Furthermore, deletion ofgalE1diminishes the capsulation ofB. anthraciswith poly-d-γ-glutamic acid (PDGA) and causes a reduction in bacterial virulence. These data suggest that SCWP galactosylation is required for the physiologic assembly of theB. anthraciscell wall envelope and for the pathogenesis of anthrax disease.IMPORTANCEUnlike virulentBacillus anthracisisolates,B. anthracisstrain CDC684 synthesizes secondary cell wall polysaccharide (SCWP) trisaccharide repeats without galactosyl modification, exhibits diminished growthin vitroin broth cultures, and is severely attenuated in an animal model of anthrax. To examine whether SCWP galactosylation is a requirement for anthrax disease, we generated variants ofB. anthracisstrains Sterne 34F2 and Ames lacking UDP-glucose 4-epimerase by mutating the genesgalE1andgalE2. We identifiedgalE1as necessary for SCWP galactosylation. Deletion ofgalE1decreased the poly-d-γ-glutamic acid (PDGA) capsulation of the vegetative form ofB. anthracisand increased the bacterial inoculum required to produce lethal disease in mice, indicating that SCWP galactosylation is indeed a determinant of anthrax disease.

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