scholarly journals A New Transformation-Deficient Mutant ofHaemophilus influenzae Rd with Normal DNA Uptake

1998 ◽  
Vol 180 (3) ◽  
pp. 746-748 ◽  
Author(s):  
M. L. Gwinn ◽  
R. Ramanathan ◽  
H. O. Smith ◽  
J.-F. Tomb
Keyword(s):  
Haemophilus Influenzae ◽  
Mutant Strain ◽  
Competence Development ◽  
Transformation Frequency ◽  
Dna Uptake ◽  
Deficient Mutant ◽  
Wild Type ◽  
Gram Negative ◽  
Ofhaemophilus Influenzae

ABSTRACT Haemophilus influenzae Rd is a gram-negative natural transformer. A mutant strain, RJ248, that has normal DNA uptake and translocation but whose transformation frequency is 300 times lower than that of wild-type H. influenzae and whose phage recombination is 8 times lower was isolated. The affected gene,comM, is induced during competence development in wild-typeH. influenzae but not in RJ248.

scholarly journals Chemical Composition and Antimicrobial Activities of Essential Oils of Four Lines of Origanum Vulgare Subsp. Hirtum (Link) Ietswaart Grown in Hungary

2007 ◽  
Vol 2 (11) ◽  
pp. 1934578X0700201 ◽  
Author(s):  
Katalin Veres ◽  
Erzsébet Varga ◽  
Zsuzsanna Schelz ◽  
József Molnár ◽  
Jenő Bernáth ◽  
...  
Keyword(s):  
Essential Oils ◽  
Staphylococcus Epidermidis ◽  
Antimicrobial Activities ◽  
Deficient Mutant ◽  
Wild Type ◽  
Bacterial Strains ◽  
Origanum Vulgare ◽  
Gram Negative ◽  
E Coli ◽  
Yeast Strains

The essential oils of four lines of Origanum vulgare L. subsp. hirtum (Link) Ietswaart cultivated in Hungary were analysed by GC and GC-MS methods. These oils were found to contain carvacrol, γ-terpinene and p-cymene as main constituents. The antimicrobial activities of the various oils and their authentic individual components were tested on Gram-positive and Gram-negative bacterial strains, two Saccharomyces cerevisiae strains and two Candida albicans strains. No difference in sensitivity was found between Escherichia coli, Staphylococcus epidermidis and the yeast strains tested, but there were marked differences in sensitivity between the proton pump-deficient mutant of E. coli and its wild type as regards the growth inhibition and MIC values.

Genetic analysis of developmental mechanisms in hydra. XIX. Stimulation of regeneration by injury in the regeneration-deficient mutant strain, reg-16

Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 521-528
Author(s):  
E. Kobatake ◽  
T. Sugiyama
Keyword(s):  
Mutant Strain ◽  
Deficient Mutant ◽  
Wild Type ◽  
Regenerative Capacity ◽  
Activation Level ◽  
Original Number ◽  
Morphogenetic Potential ◽  
Hydra Magnipapillata ◽  
Strain Mechanisms ◽  
Stimulation Of

A mutant strain of Hydra magnipapillata, reg-16, has a very low regenerative capacity. After head removal, it usually restores 10–20% of the original number of tentacles in 7 days. A procedure was found to markedly improve tentacle regeneration in this strain. The closed wound located at the apical regenerating tip of the decapitated polyp was gently reopened using a pair of forceps. Reg-16 polyps treated in this way at 24 and 48 h after head removal restored nearly all of the original number of tentacles in 7 days. A lateral tissue transplantation procedure was employed to examine the effect of wound reopening on the morphogenetic potential of decapitated reg-16 polyps. Wound reopening produced a significant increase in head activation level without producing a preceding decrease in head inhibition level. This and other observations suggest that the coupled activation-inhibition changes that normally occur after head removal from the wild-type hydra do not occur in this strain. Mechanisms responsible for the wound reopening effect and the absence of activation-inhibition coupling in the mutant strain reg-16 are discussed.

Keeping DNA Out, Letting It In

2019 ◽  
pp. 183-196
Author(s):  
Janet R. Gilsdorf
Keyword(s):  
Genetic Diversity ◽  
Cell Wall ◽  
Haemophilus Influenzae ◽  
Clinical Management ◽  
Cell Walls ◽  
Dna Uptake ◽  
Molecular Tools ◽  
Gram Negative ◽  
Challenging Environment ◽  
Basic Biology

All three meningitis bacteria (meningococci, Haemophilus influenzae, and pneumococci) are able to soak up DNA from their environments; thus, they all exhibit substantial genetic diversity. Those whose cell walls stain Gram negative (meningococci and H. influenzae) use DNA uptake signal sequences to take up the DNA, while pneumococci, which stain Gram positive and thus possess a different kind of cell wall, use a unique and less well understood mechanism. Although these interesting and important scientific discoveries have little to do with the clinical management of meningitis, they reveal a lot about the basic biology of H. influenzae and other meningitis-causing bacteria. By using the molecular tools that permit bacteria to acquire new DNA from their environments, H. influenzae bacteria are able to refashion themselves. In this way, at least a few of the bacteria in the enormous population of bacteria that live in humans are able to cope with whatever challenging environment they happen to fall into, including their transit from the throat, where they normally live, to the blood and meninges, where they cause meningitis.

scholarly journals Role of Porphyromonas gingivalis FeoB2 in Metal Uptake and Oxidative Stress Protection

2006 ◽  
Vol 74 (7) ◽  
pp. 4214-4223 ◽  
Author(s):  
Jia He ◽  
Hiroshi Miyazaki ◽  
Cecilia Anaya ◽  
Fan Yu ◽  
W. Andrew Yeudall ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mutant Strain ◽  
Parental Strain ◽  
Atmospheric Oxygen ◽  
Host Cells ◽  
Deficient Mutant ◽  
Wild Type ◽  
Stress Protection ◽  
Oxidative Stress Protection

ABSTRACT Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. It exhibits a high degree of aerotolerance and is able to survive in host cells, indicating that efficient oxidative stress protection mechanisms must be present in this organism. Manganese homeostasis plays a major role in oxidative stress protection in a variety of organisms; however, the transport and role of this metal in P. gingivalis is not well understood. Analysis of the genome of P. gingivalis W83 revealed the presence of two genes encoding homologs of a ferrous iron transport protein, FeoB1 and FeoB2. FeoB2 has been implicated in manganese accumulation in P. gingivalis. We sought to determine the role of the FeoB2 protein in metal transport as well as its contribution to resistance to oxygen radicals. Quantitative reverse transcriptase PCR analyses demonstrated that expression of feoB2 is induced in the presence of oxygen. The role of FeoB2 was investigated using an isogenic mutant strain deficient in the putative transporter. We characterized the FeoB2-mediated metal transport using 55Fe2+ and 54Mn2+. The FeoB2-deficient mutant had dramatically reduced rates of manganese uptake (0.028 pmol/min/107 bacteria) compared with the parental strain (0.33 pmol/min/107 bacteria) (after 20 min of uptake using 50 nM of 54Mn2+). The iron uptake rates, however, were higher in the mutant strain (0.75 pmol/min/107 bacteria) than in the wild type (0.39 pmol/min/107 bacteria). Interestingly, reduced survival rates were also noted for the mutant strain after exposure to H2O2 and to atmospheric oxygen compared to the parental strain cultured under the same conditions. In addition, in vitro infection of host cells with the wild type, the FeoB2-deficient mutant, and the same-site revertant revealed that the mutant had a significantly decreased capability for intracellular survival in the host cells compared to the wild-type strain. Our results demonstrate that feoB2 encodes a major manganese transporter required for protection of the bacterium from oxidative stress generated by atmospheric oxygen and H2O2. Furthermore, we show that FeoB2 and acquisition of manganese are required for intracellular survival of P. gingivalis in host cells.

DNA-binding vesicles released from the surface of a competence-deficient mutant of Haemophilus influenzae

1982 ◽  
Vol 152 (1) ◽  
pp. 441-450
Author(s):  
M F Concino ◽  
S H Goodgal
Keyword(s):  
Dna Binding ◽  
Haemophilus Influenzae ◽  
Binding Activity ◽  
Extracellular Dna ◽  
Dna Uptake ◽  
Purification Procedure ◽  
Deficient Mutant ◽  
Exogenous Dna ◽  
Dna Binding Activity ◽  
Nonionic Detergent

Haemophilus influenzae com-51, a mutant deficient in DNA uptake, produces an extracellular DNA-binding activity. The activity was specific for Haemophilus DNA and was isolated from cell-free competence medium after incubation for 100 to 130 min. Initial steps in the purification procedure resulted in the loss of detectable binding activity, but activity was restored by the addition of a nonionic detergent. The active fractions contained vesicles derived from the outer membrane of the cells. The vesicles were produced only under conditions that normally lead to competence development. The lack of competence of com-51 cells was not due to loss of protein synthesis in M-IV competence medium or to competition of extracellular protein for exogenous DNA. Results suggest that the inability of cells to bind DNA was due in part to the loss of DNA receptors that are released into the medium in membrane fragments.

scholarly journals Peroxisome reintroduction in Hansenula polymorpha requires Pex25 and Rho1

2011 ◽  
Vol 193 (5) ◽  
pp. 885-900 ◽  
Author(s):  
Ruchi Saraya ◽  
Arjen M. Krikken ◽  
Marten Veenhuis ◽  
Ida J. van der Klei
Keyword(s):  
Mutant Strain ◽  
De Novo ◽  
Hansenula Polymorpha ◽  
Protein Family ◽  
Yeast Cells ◽  
Deficient Mutant ◽  
Wild Type ◽  
Double Deletion ◽  
Insight Into

We identified two proteins, Pex25 and Rho1, which are involved in reintroduction of peroxisomes in peroxisome-deficient yeast cells. These are, together with Pex3, the first proteins identified as essential for this process. Of the three members of the Hansenula polymorpha Pex11 protein family—Pex11, Pex25, and Pex11C—only Pex25 was required for reintroduction of peroxisomes into a peroxisome-deficient mutant strain. In peroxisome-deficient pex3 cells, Pex25 localized to structures adjacent to the ER, whereas in wild-type cells it localized to peroxisomes. Pex25 cells were not themselves peroxisome deficient but instead contained a slightly increased number of peroxisomes. Interestingly, pex11 pex25 double deletion cells, in which both peroxisome fission (due to the deletion of PEX11) and reintroduction (due to deletion of PEX25) was blocked, did display a peroxisome-deficient phenotype. Peroxisomes reappeared in pex11 pex25 cells upon synthesis of Pex25, but not of Pex11. Reintroduction in the presence of Pex25 required the function of the GTPase Rho1. These data therefore provide new and detailed insight into factors important for de novo peroxisome formation in yeast.

scholarly journals The Lipid Lysyl-Phosphatidylglycerol Is Present in Membranes of Rhizobium tropici CIAT899 and Confers Increased Resistance to Polymyxin B Under Acidic Growth Conditions

2007 ◽  
Vol 20 (11) ◽  
pp. 1421-1430 ◽  
Author(s):  
Christian Sohlenkamp ◽  
Kanaan A. Galindo-Lagunas ◽  
Ziqiang Guan ◽  
Pablo Vinuesa ◽  
Sally Robinson ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Minimal Medium ◽  
Polymyxin B ◽  
Growth Conditions ◽  
Membrane Lipid ◽  
Low Ph ◽  
Wild Type ◽  
Rhizobium Tropici ◽  
Gram Negative ◽  
Inducible Genes

Lysyl-phosphatidylglycerol (LPG) is a well-known membrane lipid in several gram-positive bacteria but is almost unheard of in gram-negative bacteria. In Staphylococcus aureus, the gene product of mprF is responsible for LPG formation. Low pH-inducible genes, termed lpiA, have been identified in the gram-negative α-proteobacteria Rhizobium tropici and Sinorhizobium medicae in screens for acid-sensitive mutants and they encode homologs of MprF. An analysis of the sequenced bacterial genomes reveals that genes coding for homologs of MprF from S. aureus are present in several classes of organisms throughout the bacterial kingdom. In this study, we show that the expression of lpiA from R. tropici in the heterologous hosts Escherichia coli and Sinorhizobium meliloti causes formation of LPG. A wild-type strain of R. tropici forms LPG (about 1% of the total lipids) when the cells are grown in minimal medium at pH 4.5 but not when grown in minimal medium at neutral pH or in complex tryptone yeast (TY) medium at either pH. LPG biosynthesis does not occur when lpiA is deleted and is restored upon complementation of lpiA-deficient mutants with a functional copy of the lpiA gene. When grown in the low-pH medium, lpiA-deficient rhizobial mutants are over four times more susceptible to the cationic peptide polymyxin B than the wild type.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

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