scholarly journals MtrP, a putative methyltransferase in Corynebacteria, is required for optimal membrane transport of trehalose mycolates

2020 ◽  
Vol 295 (18) ◽  
pp. 6108-6119 ◽  
Author(s):  
Arek K. Rainczuk ◽  
Stephan Klatt ◽  
Yoshiki Yamaryo-Botté ◽  
Rajini Brammananth ◽  
Malcolm J. McConville ◽  
...  
Keyword(s):  
Cell Walls ◽  
Double Mutant ◽  
Pathogenic Bacteria ◽  
Genetic Locus ◽  
Methyltransferase Activity ◽  
Mycolic Acids ◽  
Bacterial Cell Membrane ◽  
The Individual ◽  
Cytoplasmic Side ◽  
Long Chain

Pathogenic bacteria of the genera Mycobacterium and Corynebacterium cause severe human diseases such as tuberculosis (Mycobacterium tuberculosis) and diphtheria (Corynebacterium diphtheriae). The cells of these species are surrounded by protective cell walls rich in long-chain mycolic acids. These fatty acids are conjugated to the disaccharide trehalose on the cytoplasmic side of the bacterial cell membrane. They are then transported across the membrane to the periplasm where they act as donors for other reactions. We have previously shown that transient acetylation of the glycolipid trehalose monohydroxycorynomycolate (hTMCM) enables its efficient transport to the periplasm in Corynebacterium glutamicum and that acetylation is mediated by the membrane protein TmaT. Here, we show that a putative methyltransferase, encoded at the same genetic locus as TmaT, is also required for optimal hTMCM transport. Deletion of the C. glutamicum gene NCgl2764 (Rv0224c in M. tuberculosis) abolished acetyltrehalose monocorynomycolate (AcTMCM) synthesis, leading to accumulation of hTMCM in the inner membrane and delaying its conversion to trehalose dihydroxycorynomycolate (h2TDCM). Complementation with NCgl2764 normalized turnover of hTMCM to h2TDCM. In contrast, complementation with NCgl2764 derivatives mutated at residues essential for methyltransferase activity failed to rectify the defect, suggesting that NCgl2764/Rv0224c encodes a methyltransferase, designated here as MtrP. Comprehensive analyses of the individual mtrP and tmaT mutants and of a double mutant revealed strikingly similar changes across several lipid classes compared with WT bacteria. These findings indicate that both MtrP and TmaT have nonredundant roles in regulating AcTMCM synthesis, revealing additional complexity in the regulation of trehalose mycolate transport in the Corynebacterineae.

scholarly journals The Synthesis of Modified Trehalose Glycolipids: Towards Understanding Mincle and MCL Binding

2021 ◽  
Author(s):  
◽  
Jessica Helen Bird
Keyword(s):  
Cell Walls ◽  
Biological Activities ◽  
Chain Fatty Acid ◽  
Wild Type ◽  
Mycobacterium Species ◽  
Immunostimulatory Activity ◽  
Long Chain Fatty Acid ◽  
Mycolic Acids ◽  
Adjuvant Therapies ◽  
Long Chain

<p>Trehalose glycolipids are a diverse family of long-chain fatty acid diesters isolated from the cell walls of bacteria, in particular Mycobacterium species including M. tuberculosis. These molecules possess an array of biological activities which contribute to the survival and virulence of the organism,however, it is their activity as potent stimulators of innate and early adaptive immunity for which they are of interest. In particular, trehalose glycolipids have an application as adjuvants in vaccines and immunotherapies, for diseases such as tuberculosis (TB) and cancer. Recently, the macrophage-inducible C-type lectin, Mincle, and the macrophage C-type lectin, MCL, were identified as receptors for trehalose glycolipids, however, the exact mechanisms by which these receptors recognise and bind glycolipids is, as yet, unknown.This thesis presents the synthesis of a variety of structurally diverse trehalose glycolipid analogues. As such, three mycolic acids bearing a C22 α-chain and diversified meromycolate branches were prepared from an epoxide intermediate, itself prepared in eight steps from commercially available starting materials. The mycolic acids were then coupled to TMS-trehalose and subsequently deprotected to give the mono-and diester derivatives, 1a-cand 2c, which will be assessed for their immunostimulatory activity through the activation of wild type and Mincle-/-murine macrophages. This work provides a first step towards determining how the structures of trehalose glycolipids influence Mincle and MCL binding and activity, and allow for the development of improved trehalose glycolipids for use in adjuvant therapies.</p>

scholarly journals The Synthesis of Modified Trehalose Glycolipids: Towards Understanding Mincle and MCL Binding

2021 ◽  
Author(s):  
◽  
Jessica Helen Bird
Keyword(s):  
Cell Walls ◽  
Biological Activities ◽  
Chain Fatty Acid ◽  
Wild Type ◽  
Mycobacterium Species ◽  
Immunostimulatory Activity ◽  
Long Chain Fatty Acid ◽  
Mycolic Acids ◽  
Adjuvant Therapies ◽  
Long Chain

<p>Trehalose glycolipids are a diverse family of long-chain fatty acid diesters isolated from the cell walls of bacteria, in particular Mycobacterium species including M. tuberculosis. These molecules possess an array of biological activities which contribute to the survival and virulence of the organism,however, it is their activity as potent stimulators of innate and early adaptive immunity for which they are of interest. In particular, trehalose glycolipids have an application as adjuvants in vaccines and immunotherapies, for diseases such as tuberculosis (TB) and cancer. Recently, the macrophage-inducible C-type lectin, Mincle, and the macrophage C-type lectin, MCL, were identified as receptors for trehalose glycolipids, however, the exact mechanisms by which these receptors recognise and bind glycolipids is, as yet, unknown.This thesis presents the synthesis of a variety of structurally diverse trehalose glycolipid analogues. As such, three mycolic acids bearing a C22 α-chain and diversified meromycolate branches were prepared from an epoxide intermediate, itself prepared in eight steps from commercially available starting materials. The mycolic acids were then coupled to TMS-trehalose and subsequently deprotected to give the mono-and diester derivatives, 1a-cand 2c, which will be assessed for their immunostimulatory activity through the activation of wild type and Mincle-/-murine macrophages. This work provides a first step towards determining how the structures of trehalose glycolipids influence Mincle and MCL binding and activity, and allow for the development of improved trehalose glycolipids for use in adjuvant therapies.</p>

Immunomodulatory Effect of “Dr. M.S. Reddy’s Multiple Mixed Strain Probiotic Therapy” to Cure or Prevent Hospital Acquired (Nosocomial) Infections due to Clostridium difficile (C. diff), other Pathogenic Bacteria, and Autoimmune Diseases

2018 ◽  
Vol 11 (1) ◽  
pp. 3937-3949
Author(s):  
Malireddy S Reddy
Keyword(s):  
Immune System ◽  
Gastrointestinal Tract ◽  
Pathogenic Bacteria ◽  
Molecular Level ◽  
Host Immune System ◽  
Hospital Acquired Infections ◽  
The World ◽  
Probiotic Strains ◽  
The Individual ◽  
Hospital Acquired

The worldwide popularity of Dr. M.S. Reddy’s Multiple Mixed Strain Probiotic Therapy to treat or prevent the hospital acquired infections (nosocomial infections) arose a great interest in the medical community around the world (Reddy and Reddy, 2016; 2017). The following questions were raised on this subject: Does Multiple Mixed Strain Probiotics directly inhibit the pathogenic bacteria (C. diff) in the gastrointestinal tract or indirectly through modulation of the host immune system or both? To be more specific, what is the exact and/or hypothetical mechanism at molecular level behind the breakthrough discovery of Dr. M.S. Reddy’s Multiple Mixed Strain Probiotic Therapy?  To answer these questions, the specific immunomodulation regulatory functions of the individual Probiotic strains (on host) have beenresearched, investigated andoutlined in this article.  A detailed explanation(s) and hypotheses have been proposed outlining the possible cumulativedirect bacteriological and indirect immunomodulatory effects (at the molecular level) of the Multiple Mixed Strain Probiotics used in Dr. M.S. Reddy’s Multiple Mixed Strain Probiotic Therapy to successfully treat C. diff infection.  A detailed scientific and research attempts were made to correlate the Probiotic induced immune activities in relation to the reduction of the symptoms associated with the hospital acquired Clostridium difficile infection during and after the Multiple Mixed Strain Probioitc Therapy.  Results of the clinical trials, microbiological tests on feces, and the clinical blood tests significantly revealed that the reasons for the success of Dr. Reddy’s Multiple Mixed Strain Probiotic Therapy are multifold. Presumably, it is predominantly due to the immunomodulatory effect they have exerted on the host immune system along with the direct inhibition of C. diff bacteria by multiple Probiotics, due to the production of bacteriocins, lactic acid and nutritional competency.In addition, the size of the individual cells of the Probiotic strains in the Multiple Mixed Strain Probiotics and their significant effect on immunomodulation has been thoroughly discussed. Results clearly proved that if Probiotics are absent in the GI tract during C. diff infection, the chances of patient survival is zero.  This is because of the excess immune stimulation and incurable damage to the epithelial cell barrier of the gastrointestinal tract caused by C. diff bacteria.  The results also revealed, without any doubt, as of to-datethe latest discovery of Dr. M.S. Reddy’s Multiple Mixed Strain Probiotic Therapy is the best way to cure the deadly hospital acquired infections affecting millions of people around the world, with high degree of mortality.  This has been attested by several practicng medical professionals and scientists around the world (Reddy and Reddy, 2017).

scholarly journals Multiple Mechanisms of Action for Inhibitors of Histidine Protein Kinases from Bacterial Two-Component Systems

1999 ◽  
Vol 43 (7) ◽  
pp. 1693-1699 ◽  
Author(s):  
Jamese J. Hilliard ◽  
Raul M. Goldschmidt ◽  
Lisa Licata ◽  
Ellen Z. Baum ◽  
Karen Bush
Keyword(s):  
Pathogenic Bacteria ◽  
Response Regulator ◽  
Membrane Integrity ◽  
Bacterial Killing ◽  
Gram Positive Bacteria ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Bacterial Cell Membrane ◽  
Cellular Incorporation

ABSTRACT Many pathogenic bacteria utilize two-component systems consisting of a histidine protein kinase (HPK) and a response regulator (RR) for signal transduction. During the search for novel inhibitors, several chemical series, including benzoxazines, benzimidazoles, bis-phenols, cyclohexenes, trityls, and salicylanilides, were identified that inhibited the purified HPK-RR pairs KinA-Spo0F and NRII-NRI, with 50% inhibitory concentrations (IC50s) ranging from 1.9 to >500 μM and MICs ranging from 0.5 to >16 μg/ml for gram-positive bacteria. However, additional observations suggested that mechanisms other than HPK inhibition might contribute to antibacterial activity. In the present work, representative compounds from the six different series of inhibitors were analyzed for their effects on membrane integrity and macromolecular synthesis. At 4× MIC, 17 of 24 compounds compromised the integrity of the bacterial cell membrane within 10 min, as measured by uptake of propidium iodide. In this set, compounds with lower IC50s tended to cause greater membrane disruption. Eleven of 12 compounds inhibited cellular incorporation of radiolabeled thymidine and uridine >97% in 5 min and amino acids >80% in 15 min. The HPK inhibitor that allowed >25% precursor incorporation had no measurable MIC (>16 μg/ml). Fifteen of 24 compounds also caused hemolysis of equine erythrocytes. Thus, the antibacterial HPK inhibitors caused a rapid decrease in cellular incorporation of RNA, DNA, and protein precursors, possibly as a result of the concomitant disruption of the cytoplasmic membrane. Bacterial killing by these HPK inhibitors may therefore be due to multiple mechanisms, independent of HPK inhibition.

Antibacterial Effects of Long-Chain Polyphosphates on Selected Spoilage and Pathogenic Bacteria

2008 ◽  
Vol 71 (7) ◽  
pp. 1401-1405 ◽  
Author(s):  
JEREMY A. OBRITSCH ◽  
DOJIN RYU ◽  
LUCINA E. LAMPILA ◽  
LLOYD B. BULLERMAN
Keyword(s):  
Food Industry ◽  
Pathogenic Bacteria ◽  
Antimicrobial Activities ◽  
Lag Phase ◽  
E Coli ◽  
Inhibition Of Growth ◽  
K 12 ◽  
Chain Lengths ◽  
And Staphylococcus Aureus ◽  
Long Chain

The antimicrobial activities of four long-chain food-grade polyphosphates were studied at concentrations allowed in the food industry (&lt;5,000 ppm) in defined basal media by determining the inhibition of growth of three gram-negative and four gram-positive spoilage and pathogenic bacteria. Both generation time and lag phase of Escherichia coli K-12, E. coli O157: H7, and Salmonella Typhimurium were increased with all of the polyphosphates tested. Bacillus subtilis and Staphylococcus aureus were more sensitive to polyphosphates, but not in all cases, with multiphased growth. The growth of Lactobacillus plantarum was inhibited by polyphosphates at concentrations above 750 ppm, but the lag time of Listeria monocytogenes was shortened by the presence of polyphosphates. No single polyphosphate was maximally inhibitory against all bacteria. Polyphosphates with chain lengths of 12 to 15 were significantly different from those with chain lengths of 18 to 21 depending on the organism and concentrations of polyphosphate used. Overall, higher polyphosphate concentrations resulted in greater inhibition of bacterial growth.

scholarly journals Redundant Function of cmaA2 and mmaA2 in Mycobacterium tuberculosis cis Cyclopropanation of Oxygenated Mycolates

2010 ◽  
Vol 192 (14) ◽  
pp. 3661-3668 ◽  
Author(s):  
Daniel Barkan ◽  
Vivek Rao ◽  
George D. Sukenick ◽  
Michael S. Glickman
Keyword(s):  
Fatty Acids ◽  
Mycobacterium Tuberculosis ◽  
Genetic Analysis ◽  
Biosynthetic Pathway ◽  
Cell Envelope ◽  
Mycolic Acid ◽  
Acid Modification ◽  
Mycolic Acids ◽  
Powerful Approach ◽  
Long Chain

ABSTRACT The Mycobacterium tuberculosis cell envelope contains a wide variety of lipids and glycolipids, including mycolic acids, long-chain branched fatty acids that are decorated by cyclopropane rings. Genetic analysis of the mycolate methyltransferase family has been a powerful approach to assign functions to each of these enzymes but has failed to reveal the origin of cis cyclopropanation of the oxygenated mycolates. Here we examine potential redundancy between mycolic acid methyltransferases by generating and analyzing M. tuberculosis strains lacking mmaA2 and cmaA2, mmaA2 and cmaA1, or mmaA1 alone. M. tuberculosis lacking both cmaA2 and mmaA2 cannot cis cyclopropanate methoxymycolates or ketomycolates, phenotypes not shared by the mmaA2 and cmaA2 single mutants. In contrast, a combined loss of cmaA1 and mmaA2 had no effect on mycolic acid modification compared to results with a loss of mmaA2 alone. Deletion of mmaA1 from M. tuberculosis abolishes trans cyclopropanation without accumulation of trans-unsaturated oxygenated mycolates, placing MmaA1 in the biosynthetic pathway for trans-cyclopropanated oxygenated mycolates before CmaA2. These results define new functions for the mycolic acid methyltransferases of M. tuberculosis and indicate a substantial redundancy of function for MmaA2 and CmaA2, the latter of which can function as both a cis and trans cyclopropane synthase for the oxygenated mycolates.

scholarly journals Nontypeable Pneumococci Can Be Divided into Multiple cps Types, Including One Type Expressing the Novel Gene pspK

mBio ◽  
2012 ◽  
Vol 3 (3) ◽  
Author(s):  
In Ho Park ◽  
Kyung-Hyo Kim ◽  
Ana Lucia Andrade ◽  
David E. Briles ◽  
Larry S. McDaniel ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Capsular Polysaccharide ◽  
Genetic Locus ◽  
The Novel ◽  
Content Type ◽  
Capsule Production ◽  
Polysaccharide Synthesis ◽  
Definition Of ◽  
Survival Mechanisms ◽  
Helical Region

ABSTRACTAlthough virulence ofStreptococcus pneumoniaeis associated with its capsule, some pathogenicS. pneumoniaeisolates lack capsules and are serologically nontypeable (NT). We obtained 64 isolates that were identified as NT “pneumococci” (i.e., bacteria satisfying the conventional definition but without the multilocus sequence typing [MLST]-based definition ofS. pneumoniae) by the traditional criteria. All 64 were optochin sensitive and hadlytA, and 63 hadply. Twelve isolates hadcpsA, suggesting the presence of a conventional but defective capsular polysaccharide synthesis (cps) locus. The 52cpsA-negative isolates could be divided into three null capsule clades (NCC) based onaliC(aliB-like ORF1),aliD(aliB-like ORF2), and our newly discovered gene,pspK, in theircpsloci.pspKencodes a protein with a long alpha-helical region containing an LPxTG motif and a YPT motif known to bind human pIgR. There were nine isolates in NCC1 (pspK+but negative foraliCandaliD), 32 isolates in NCC2 (aliC+aliD+but negative forpspK), and 11 in NCC3 (aliD+but negative foraliCandpspK). Among 52cpsA-negative isolates, 41 were identified asS. pneumoniaeby MLST analysis. All NCC1 and most NCC2 isolates wereS. pneumoniae, whereas all nine NCC3 and two NCC2 isolates were notS. pneumoniae. Several NCC1 and NCC2 isolates from multiple individuals had identical MLST andcpsregions, showing that unencapsulatedS. pneumoniaecan be infectious among humans. Furthermore, NCC1 and NCC2S. pneumoniaeisolates could colonize mice as well as encapsulatedS. pneumoniae, althoughS. pneumoniaewith an artificially disruptedcpslocus did not. Moreover, an NCC1 isolate withpspKdeletion did not colonize mice, suggesting thatpspKis critical for colonization. Thus, PspK may provide pneumococci a means of surviving in the nasopharynx without capsule.IMPORTANCEThe presence of a capsule is critical for many pathogenic bacteria, including pneumococci. Reflecting the pathogenic importance of the pneumococcal capsule, pneumococcal vaccines are designed to elicit anticapsule antibodies. Additional evidence for the pathogenic importance of the pneumococcal capsule is the fact that in pneumococci all the genes necessary for capsule production are together in one genetic locus, which is called thecpslocus. However, there are occasional pathogenic pneumococci without capsules, and how they survive in the host without the capsule is unknown. Here, we show that in these acapsular pneumococci, thecpsloci have been replaced with various novel genes and they can colonize mouse nasopharynges as well as capsulated pneumococci. Since the genes that replace thecpsloci are likely to be important in host survival, they may show new and/or alternative capsule-independent survival mechanisms used by pneumococci.

Synthesis of cell wall glucan, chitin, and protein by regenerating protoplasts and mycelia of Trichoderma reesei

1990 ◽  
Vol 36 (3) ◽  
pp. 211-217 ◽  
Author(s):  
Robert Messner ◽  
Christian P. Kubicek
Keyword(s):  
Cell Wall ◽  
Trichoderma Reesei ◽  
Cell Walls ◽  
Cell Wall Protein ◽  
Protoplast Regeneration ◽  
Secretory Proteins ◽  
Soluble Cell ◽  
Cell Wall Biogenesis ◽  
The Individual ◽  
Specific Labelling

The synthesis of constituent polymers of the cell wall by either growing mycelia or regenerating protoplasts of Trichoderma reesei QM 9414 was investigated by following the incorporation of radioactive precursors of the individual polymers (i.e., N[14C] acetyl-glucosamine, [3H] and [14C]glucose, [14C]mannose, and [35S]methionine) into individual fractions. N-Acetyl-glucosamine and glucose were found to become specifically incorporated into cell wall chitin and glucan by both mycelia and regenerating protoplasts, indicating the activity of chitin and glucan synthases in both systems. Cell wall glucan from regenerating protoplasts, however, consisted only of α-glucan and specifically lacked β-glucan which is found in mycelial cell walls. Mannose became metabolized to glucose before its label appeared in the cell wall, and was thus unsuitable for specific labelling. [35S]Methionine was found in a small (< 21 kDa) polypeptide from the first alkali-soluble cell wall fraction, but also in cell wall bound secretory proteins, i. e., β-glucosidase. These results indicate that cell wall biogenesis in T. reesei, in contrast to a report by other authors, is similar to that of other filamentous fungi. Key words: Trichoderma reesei, protoplast regeneration, cell wall polymer, β-glucan, cell wall protein.

Statistical Thermodynamics of Rubber. II

1942 ◽  
Vol 15 (4) ◽  
pp. 806-811 ◽  
Author(s):  
Frederick T. Wall
Keyword(s):  
Point Of View ◽  
The Other ◽  
Lower Probability ◽  
Statistical Nature ◽  
Macroscopic Theory ◽  
Hooke’S Law ◽  
Hooke's Law ◽  
The Individual ◽  
Long Chain ◽  
Made In

Abstract During recent years, considerable progress has been made in connection with theories of rubber elasticity. Two general types of theories have been advanced, one from a macroscopic point of view and the other from a molecular point of view. An example of the former is the theory of Mooney, who arrived at an equation which agrees well with observation. For molecular theories, the reader is referred to the work of Guth and Mark, Kuhn, and Pelzer, who carried through calculations of a statistical nature. More recently, the author extended the statistical theory along lines which avoided some of the earlier difficulties. In the present paper, the calculations will be carried still further, and the molecular theory will be related to the macroscopic theory of Mooney. It will also be shown theoretically that, although rubber does not obey Hooke's law for ordinary elongation, it should obey Hooke's law for shear. It will be supposed that individual rubber molecules are long chain hydrocarbons capable of assuming various lengths and shapes as a result of free rotation about carbon-to-carbon valence bonds. When a piece of rubber is under no stress, the rubber molecules have a certain distribution of shapes. When the rubber is subjected to a stress, however, the molecules assume another distribution of lower probability. The theory here advanced relates this probability to the entropy of strain, thus providing a means of arriving at the mechanical properties of rubber. Two postulates are made. (1) When a macroscopic piece of rubber is strained, the components of the lengths of the individual molecules (along some set of axes) change in the same ratio as does the corresponding dimension of the piece of rubber. (2) When a piece of rubber is elongated, no change in total volume takes place. The first assumption was made in the earlier paper of this series, whereas the second was not. Experimental support for the second postulate has been given by Holt and McPherson. Our first problem is to investigate the effect of this second assumption on the equation of state for rubber.

Effect of supplementary energy and protein feeding on the true digestion of grass-silage organic matter, cell walls and nitrogen estimated by the combined synthetic-fibre-bag method in cows

1992 ◽  
Vol 72 (3) ◽  
pp. 671-678 ◽  
Author(s):  
Tuomo Varvikko ◽  
Aila Vanhatalo
Keyword(s):  
Organic Matter ◽  
Cell Walls ◽  
Latin Square ◽  
Rapeseed Meal ◽  
Concentrate Supplementation ◽  
Rumen Degradation ◽  
Grass Silage ◽  
Intestinal Digestion ◽  
Ruminal Degradation ◽  
The Individual

Four ruminally and duodenally cannulated non-lactating Finnish Ayrshire cows were used in a balanced 4 × 4 Latin square to study the effect of different concentrate supplements on the true partial and total-tract digestion (TTD) of grass silage, estimated by using the combined rumen-bag-intestinal-bag method. The cows were fed, at maintenance level, grass silage alone or supplemented with good-quality ground barley, ground barley and rapeseed meal, or ground barley and soybean meal. The determination of the proportion of grass silage degraded in the rumen (RD) was based on disappearance of feeds from nylon bags during the rumen incubation as a function of time, using the outflow rate of k = 0.0625. The intestinal digestion (ID) was estimated by the mobile-bag method with the residues that resisted degradation during the 16-h rumen incubation. Combination of these two was calculated to provide the TTD. Concentrate supplementation always caused a clear and consistent decline in rumen degradation and TTD of organic matter (OM), neutral detergent fibre (NDF) and Kjeldahl-N of grass silage but had no real influence on its ID. The type of concentrate, however, had only little effect. The average TTD of NDF was 16% lower than that of OM, but TTD of N was always very much higher than the respective value for OM. The results indicate that concentrate supplementation decreases the total-tract digestion of OM, cell walls and nitrogen of grass silage owing to impaired ruminal degradation. The combined bag method appears a convenient tool to provide digestion coefficients close to the true feed digestion of the individual feeds. Key words: Grass silage, nylon bag, mobile bag, combined bag, ruminal degradation, intestinal digestion, true digestion

Sign in / Sign up

Export Citation Format

Share Document