The bacterial tyrosine kinase system CpsBCD governs the length of capsule polymers

2021 ◽  
Vol 118 (45) ◽  
pp. e2103377118
Author(s):  
Rei Nakamoto ◽  
Jeric Mun Chung Kwan ◽  
Jasmine Fei Li Chin ◽  
Hui Ting Ong ◽  
Josue Flores-Kim ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Pathogenic Bacteria ◽  
Capsular Polysaccharide ◽  
Fine Tuning ◽  
Low Molecular Weight ◽  
Tyrosine Residues ◽  
Undecaprenyl Phosphate ◽  
External Stimuli ◽  
Spatiotemporal Coordination

Many pathogenic bacteria are encased in a layer of capsular polysaccharide (CPS). This layer is important for virulence by masking surface antigens, preventing opsonophagocytosis, and avoiding mucus entrapment. The bacterial tyrosine kinase (BY-kinase) regulates capsule synthesis and helps bacterial pathogens to survive different host niches. BY-kinases autophosphorylate at the C-terminal tyrosine residues upon external stimuli, but the role of phosphorylation is still unclear. Here, we report that the BY-kinase CpsCD is required for growth in Streptococcus pneumoniae. Cells lacking a functional cpsC or cpsD accumulated low molecular weight CPS and lysed because of the lethal sequestration of the lipid carrier undecaprenyl phosphate, resulting in inhibition of peptidoglycan (PG) synthesis. CpsC interacts with CpsD and the polymerase CpsH. CpsD phosphorylation reduces the length of CPS polymers presumably by controlling the activity of CpsC. Finally, pulse–chase experiments reveal the spatiotemporal coordination between CPS and PG synthesis. This coordination is dependent on CpsC and CpsD. Together, our study provides evidence that BY-kinases regulate capsule polymer length by fine-tuning CpsC activity through autophosphorylation.

scholarly journals Role of RpoS in Fine-Tuning the Synthesis of Vi Capsular Polysaccharide in Salmonella enterica Serotype Typhi

2006 ◽  
Vol 75 (3) ◽  
pp. 1382-1392 ◽  
Author(s):  
Javier Santander ◽  
Soo-Young Wanda ◽  
Cheryl A. Nickerson ◽  
Roy Curtiss
Keyword(s):  
Salmonella Enterica ◽  
Capsular Polysaccharide ◽  
Fine Tuning ◽  
O Antigen ◽  
Native Promoter ◽  
Regulatory Systems ◽  
Polysaccharide Synthesis ◽  
Clinical Detection ◽  
Vi Capsular Polysaccharide

ABSTRACT Regulation of the synthesis of Vi polysaccharide, a major virulence determinant in Salmonella enterica serotype Typhi, is under the control of two regulatory systems, ompR-envZ and rscB-rscC, which respond to changes in osmolarity. Some serotype Typhi strains exhibit overexpression of Vi polysaccharide, which masks clinical detection of lipopolysaccharide O antigen. This variation in Vi polysaccharide and O antigen display (VW variation) has been observed since the initial studies of serotype Typhi. In this study, we report that rpoS plays a role in this increased expression in Vi polysaccharide. We constructed a variety of isogenic serotype Typhi mutants that differed in their expression levels of RpoS and examined the role of the rpoS product in synthesis of Vi polysaccharide under different osmolarity conditions. Vi polysaccharide synthesis was also examined in serotype Typhi mutants in which the native promoter of the rpoS was replaced by an araCPBAD cassette, so that the expression of rpoS was arabinose dependent. The RpoS− strains showed increased syntheses of Vi polysaccharide, which at low and medium osmolarities masked O antigen detection. In contrast, RpoS+ strains showed lower syntheses of Vi polysaccharide, and an increased detection of O antigen was observed. During exponential growth, when rpoS is unstable or present at low levels, serotype Typhi RpoS+ strains overexpress the Vi polysaccharide at levels comparable to those for RpoS− strains. Our results show that RpoS is another regulator of Vi polysaccharide synthesis and contributes to VW variation in serotype Typhi, which has implications for the development of recombinant attenuated Salmonella vaccines in humans.

scholarly journals Stimulation of Fc gamma RIIIA results in phospholipase C-gamma 1 tyrosine phosphorylation and p56lck activation.

1992 ◽  
Vol 176 (6) ◽  
pp. 1745-1750 ◽  
Author(s):  
L Azzoni ◽  
M Kamoun ◽  
T W Salcedo ◽  
P Kanakaraj ◽  
B Perussia
Keyword(s):  
T Cells ◽  
Tyrosine Kinase ◽  
Nk Cells ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Phosphorylation ◽  
Protein Tyrosine ◽  
Tyrosine Residues ◽  
Stimulation Of

Binding of ligand to the alpha subunit of Fc gamma RIIIA(CD16), expressed at the natural killer (NK) cell membrane in association with homo or heterodimers of proteins of the zeta family, results in phosphorylation of several proteins on tyrosine residues. We have analyzed the role of protein tyrosine phosphorylation in the regulation of molecular events induced upon stimulation of Fc gamma RIIIA in NK cells and in T cells expressing the Fc gamma RIII alpha chain in association with endogenous zeta 2 homodimers and devoid of other (CD3, CD2) transducing molecules. Our data indicate that treatment of these cells with protein tyrosine kinase inhibitors prevents not only Fc gamma RIIIA-induced protein tyrosine phosphorylation but also phosphatidylinositol 4,5 diphosphate hydrolysis and increased intracellular Ca2+ concentration, indicating a primary role of tyrosine kinase(s) in the induction of these early activation events. Occupancy of Fc gamma RIIIA by ligand results in phospholipase C (PLC)-gamma 1 tyrosine phosphorylation in NK cells and in Fc gamma RIIIA-transfected CD3-/CD2- T cells, and induces functional activation of p56lck in Fc gamma RIIIA alpha/zeta 2-transfected T cells, suggesting the possibility that the receptor-induced PLC-gamma 1 activation occurs upon phosphorylation of its tyrosine residues mediated by this kinase and is, at least in part, responsible for the signal transduction mediated via CD16 upon ligand binding.

scholarly journals Mutational Analysis of the Carboxy-Terminal (YGX)4 Repeat Domain of CpsD, an Autophosphorylating Tyrosine Kinase Required for Capsule Biosynthesis in Streptococcus pneumoniae

2003 ◽  
Vol 185 (10) ◽  
pp. 3009-3019 ◽  
Author(s):  
Judy K. Morona ◽  
Renato Morona ◽  
David C. Miller ◽  
James C. Paton
Keyword(s):  
Streptococcus Pneumoniae ◽  
Tyrosine Kinase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Capsular Polysaccharide ◽  
Wild Type ◽  
Protein Tyrosine ◽  
Tyrosine Residues ◽  
Repeat Domain ◽  
Carboxy Terminal

ABSTRACT In Streptococcus pneumoniae, CpsB, CpsC, and CpsD are essential for encapsulation, and mutants containing deletions of cpsB, cpsC, or cpsD exhibit rough colony morphologies. CpsD is an autophosphorylating protein-tyrosine kinase, CpsC is required for CpsD tyrosine phosphorylation, and CpsB is a phosphotyrosine-protein phosphatase. We have previously shown that autophosphorylation of CpsD at tyrosine attenuates its activity and consequently reduces the level of encapsulation and negatively regulates CPS production. In this study, we further investigated the role of the carboxy-terminal (YGX)4 repeat domain of CpsD in encapsulation. A CpsD truncation mutant in which the entire (YGX)4 repeat domain was removed was indistinguishable from a strain in which the entire cpsD gene had been deleted, indicating that the carboxy-terminal (YGX)4 tail is required for CpsD activity in capsular polysaccharide production. Double mutants having a single tyrosine residue at position 2, 3, or 4 in the (YGX)4 repeat domain and lacking CpsB exhibited a rough colony morphology, indicating that in the absence of an active protein-tyrosine phosphatase, phosphorylation of just one of the tyrosine residues in the (YGX)4 repeat was sufficient to inactivate CpsD. When various mutants in which CpsD had either one or combinations of two or three tyrosine residues in the (YGX)4 repeat domain were examined, only those with three tyrosine residues in the (YGX)4 repeat domain were indistinguishable from the wild-type strain. The mutants with either one or two tyrosine residues exhibited mucoid colony morphologies. Further analysis of the mucoid strains indicated that the mucoid phenotype was not due to overproduction of capsular polysaccharide, as these strains actually produced less capsular polysaccharide than the wild-type strain. Thus, the tyrosine residues in the (YGX)4 repeat domain are essential for normal functioning of CpsD.

Fine tuning of molecular and supramolecular properties of simple trianglimines – the role of the functional group

RSC Advances ◽  
2016 ◽  
Vol 6 (58) ◽  
pp. 53358-53369 ◽  
Author(s):  
J. Gajewy ◽  
J. Szymkowiak ◽  
M. Kwit
Keyword(s):  
Molecular Weight ◽  
Asymmetric Synthesis ◽  
Functional Group ◽  
Fine Tuning ◽  
Low Molecular Weight

Readily available chiral, triangular poly-azamacrocycles can act as receptors, low molecular weight supergelators and ligands in asymmetric synthesis.

scholarly journals Tyrosine Kinase-Directed Ubiquitin Ligases Cbl and Cbl-b Enforce Hematopoietic Stem Cell Quiescence By Negatively Regulating c-Kit and FLT3

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4313-4313
Author(s):  
Wei An ◽  
Scott Nadeau ◽  
Bhopal Mohapatra ◽  
Dan Feng ◽  
Neha Zutshi ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Ubiquitin Ligases ◽  
Fine Tuning ◽  
Double Knockout ◽  
Hematopoietic Stem ◽  
Mechanistic Basis

Abstract Maintenance of quiescent hematopoietic stem cells (HSCs) is essential for life-long hematopoiesis. A prominent category of HSC quiescence regulators that determine HSC fate by directly interacting with niche-derived growth factors are receptor tyrosine kinases (RTKs). Cbl and Cbl-b are E3 ubiquitin ligases that are directed to activated tyrosine kinases and negatively regulate a number of cellular activation pathways. Previously, we established a conditional Cbl and Cbl-b double knockout (DKO) mouse strain using MMTV-Cre to delete floxed Cbl on a Cbl-b-null background, and identified that Cbl and Cbl-b function redundantly in controlling the growth factor-induced proliferation of HSCs. These DKO mice developed a rapidly fatal myeloproliferative disorder (MPD) accompanied by expansion of the HSC compartment. However, how the negative regulatory functions of Cbl-family proteins are integrated into HSC homeostatic program and the mechanistic basis for their role remain unknown. Here, we utilize mouse models to examine the functional role of Cbl and Cbl-b in regulating HSCs and its potential mechanistic basis. Transplant analyses revealed that DKO HSCs are the disease-initiating cells. However, in vitro serial colony-forming assays showed that DKO HSCs possess a reduced colony-forming ability despite their hyper-proliferative status. Cell cycle analyses demonstrated a smaller pool of quiescent long-term HSCs in DKO mice. Non-responder assays in vivo showed a reduced frequency of functional HSCs in the DKO LSK compartment and serial HSC transplantation demonstrated compromised reconstitution ability of DKO HSCs, especially at the 2nd round of transplantation. Mechanistically, DKO HSCs exhibit sustained signaling in response to c-Kit and FLT3 ligands, especially via p-Akt but also p-Erk and p-S6. The ligand-induced cell surface c-Kit and FLT3 receptor downregulation was slower in DKO HSCs. Furthermore, while c-Kit and FLT3 ligands promote higher proliferation of DKO bone marrow cells, this hyper-proliferation leads to loss of colony-forming potential that is significantly reversed by respective kinase inhibitors. Together, our data reveal a novel and physiologically essential role of Cbl and Cbl-b in the enforcement of HSC quiescence and protection against exhaustion by fine-tuning the signaling pathways downstream of tyrosine kinase-coupled receptors such as c-Kit and FLT3. These findings could have significant implications for hematological neoplasms associated with mutations of Cbl. Disclosures No relevant conflicts of interest to declare.

scholarly journals Membrane linkage of a Streptococcus pneumoniae Wzy capsular polysaccharide occurs through an acylglycerol

2020 ◽  
Author(s):  
Thomas R. Larson ◽  
Janet Yother
Keyword(s):  
Streptococcus Pneumoniae ◽  
Pathogenic Bacteria ◽  
Capsular Polysaccharide ◽  
Repeat Unit ◽  
Capsular Polysaccharides ◽  
Outer Face ◽  
Gram Positive ◽  
Bacterial Surface ◽  
Gram Positive Bacteria ◽  
Undecaprenyl Phosphate

ABSTRACTCapsular polysaccharides (capsules) protect bacteria from environmental insults and can contribute to virulence in pathogenic bacteria. Their appropriate display on the bacterial surface is critical to their functions. In Gram-positive bacteria, most capsules are synthesized by the Wzy polymerase-dependent pathway, which is also utilized in the synthesis of many capsules and O-antigens of Gram-negative bacteria. Synthesis of capsule repeat units initiates on undecaprenyl-phosphate on the inner face of the cytoplasmic membrane, with polymerization occurring on the outer face of the membrane. In Gram-positive bacteria, the capsule can be transferred to peptidoglycan, as in Streptococcus pneumoniae where a direct glycosidic bond to the peptidoglycan N-acetylglucosamine occurs. In S. pneumoniae, capsule can also be detected on the membrane, and this has generally been assumed to reflect polysaccharide that is linked to undecaprenyl-phosphate and in the process of synthesis. We provide evidence here, however, that final membrane linkage occurs through an acylglycerol, and essentially all of the polysaccharide is transferred from the initial undecaprenyl-phosphate acceptor to an alternate acceptor. This step allows for recycling of undecaprenyl-phosphate and represents an additional terminal step in capsule synthesis. In this regard, capsule synthesis resembles that of the wall- and lipoteichoic acids of S. pneumoniae, wherein a common repeat unit and polymer structure are synthesized by the Wzy pathway with divergence at the terminal step that results in linkages to peptidoglycan and a membrane acylglycerol anchor.IMPORTANCELinkage of capsular polysaccharides to the bacterial cell surface is a critical step in assuring the ability of these polymers to fulfill their functions, such as the resistance to complement-mediated phagocytosis that can be essential for pathogenic organisms to survive in host environments. Knowledge of the mechanisms by which these linkages occur is incomplete. In this study, we provide evidence for linkage of an S. pneumoniae Wzy capsule to an acylglycerol, the most abundant class of lipids in the membrane. This linkage provides a terminal acceptor for capsule that occurs in addition to that of peptidoglycan. Transfer to these terminal receptors is an essential step in CPS synthesis, as failure to do so can be lethal for the cell.

A REVIEW ON THE ROLE OF TYROSINE KINASE INHIBITORS AVAILABLE FOR THE MANAGEMENT OF CHRONIC MYELOID LEUKEMIA

2020 ◽  
Vol 7 (2) ◽  
pp. 205-211
Author(s):  
Kaynat Fatima ◽  
Syed Tasleem Raza ◽  
Ale Eba ◽  
Sanchita Srivastava ◽  
Farzana Mahdi
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Protein Kinases ◽  
Tyrosine Kinase Inhibitors ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Line Treatment ◽  
First Line ◽  
First Line Treatment

The function of protein kinases is to transfer a γ-phosphate group from ATP to serine, threonine, or tyrosine residues. Many of these kinases are linked to the initiation and development of human cancer. The recent development of small molecule kinase inhibitors for the treatment of different types of cancer in clinical therapy has proven successful. Significantly, after the G-protein-coupled receptors, protein kinases are the second most active category of drug targets. Imatinib mesylate was the first tyrosine kinase inhibitor (TKI), approved for chronic myeloid leukemia (CML) treatment. Imatinib induces appropriate responses in ~60% of patients; with ~20% discontinuing therapy due to sensitivity, and ~20% developing drug resistance. The introduction of newer TKIs such as, nilotinib, dasatinib, bosutinib, and ponatinib has provided patients with multiple options. Such agents are more active, have specific profiles of side effects and are more likely to reach the necessary milestones. First-line treatment decisions must be focused on CML risk, patient preferences and comorbidities. Given the excellent result, half of the patients eventually fail to seek first-line treatment (due to discomfort or resistance), with many of them needing a third or even further therapy lines. In the present review, we will address the role of tyrosine kinase inhibitors in therapy for chronic myeloid leukemia.

Bioenhancing Effect of Cow Urine Distillate and Pepper Extract on Antibacterial Activity of Azadirachta Indica Leaves

1970 ◽  
Vol 9 (2) ◽  
pp. 3212-3214
Author(s):  
Pramod Dhakal ◽  
Ankit a Achary ◽  
Vedamurthy Joshi
Keyword(s):  
Antibacterial Activity ◽  
Azadirachta Indica ◽  
Pathogenic Bacteria ◽  
Ethanol Extract ◽  
Watery Diarrhea ◽  
Diffusion Method ◽  
E Coli ◽  
Drug Molecules ◽  
Cow Urine

Bioenhancers are drug facilitator which do not show the typical drug activity but in combination to enhance the activity of other molecule in several way including increase the bioavailability of drug across the membrane, potentiating the drug molecules by conformational interaction, acting as receptor for drug molecules and making target cell more receptive to drugs and promote and increase the bioactivity or bioavailability or the uptake of drugs in combination therapy. The objective of the present study was to evaluate the antibacterial and activity of combination in Azadirachta indica extract with cow urine distillate and pepper extract against common pathogenic bacteria, a causative agent of watery diarrhea. It has been found that Indian indigenous cow urine and its distillate also possess bioenhancing ability. Bioenhancing role of cow urine distillate (CUD) and pepper extract was investigated on antibacterial activity of ethanol extract of Azadirachta indica. Antibacterial activity of ethanol extract neem alone and in combination with CUD and pepper extract were determined the ATCC strains against Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and E-coli by cup plate diffusion method. Ethanol extract of neem has showed more effect on P. aeruginosa, E-coli than S. aureus and K. pneumonia with combination of CUD and pepper extract. CUD and pepper did not show any inhibition of test bacteria in low concentration. The antibacterial effect of combination of extract and CUD was higher than the inhibition caused by extract alone and is suggestive of the bioenhancing role of cow urine distillate and pepper. Moreover, inhibition of test bacteria was observed with less concentration of extract on combining with CUD

Sign in / Sign up

Export Citation Format

Share Document