scholarly journals Occurrence of cross-resistance and β-lactam seesaw effect in glycopeptide-, lipopeptide- and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels

2020 ◽  
Vol 75 (5) ◽  
pp. 1182-1186 ◽  
Author(s):  
Kelly M Hines ◽  
Tianwei Shen ◽  
Nathaniel K Ashford ◽  
Adam Waalkes ◽  
Kelsi Penewit ◽  
...  
Keyword(s):  
Cell Wall ◽  
Susceptibility Testing ◽  
Membrane Lipid ◽  
Cross Resistance ◽  
Membrane Composition ◽  
Membrane Lipid Composition ◽  
Usa300 Strain ◽  
Associated Proteins ◽  
The Relationship

Abstract Background Glycopeptides (GPs), lipopeptides (LPs) and lipoglycopeptides (LGPs) are related antimicrobials important for the management of invasive MRSA infections. Cross-resistance among these antibiotics in MRSA is well documented, as is the observation that susceptibility of MRSA to β-lactams increases as susceptibility to GPs and LPs decreases (i.e. the seesaw effect). Efforts to understand the relationship between GP/LP/LGP cross-resistance and the seesaw effect have focused on the PBPs, but the role of lipid metabolism has not been investigated. Objectives Since the cell membrane is structurally and metabolically integrated with the cell wall and anchors associated proteins, including PBPs, we examined the relationship between membrane lipid composition and the phenomena of cross-resistance among GPs/LPs/LGPs and the β-lactam seesaw effect. Methods We selected for daptomycin, vancomycin and dalbavancin resistance using the USA300 strain JE2 and evaluated the resulting mutants by WGS, MS-based lipidomics and antimicrobial susceptibility testing to assess the relationship between membrane composition, cross-resistance, and the seesaw effect. Results We observed cross-resistance to GPs/LPs/LGPs among the selected strains and the seesaw effect against various β-lactams, depending on the PBP targets of the particular β-lactam. We found that modification of membrane composition occurs not only in daptomycin-selected strains, but also vancomycin- and dalbavancin-selected strains. Significantly, we observed that the abundance of most phosphatidylglycerols positively correlates with MICs of GPs/LPs/LGPs and negatively correlates with the MICs of β-lactams. Conclusions These studies demonstrate a major association between membrane remodelling, cross-resistance and the seesaw effect.

scholarly journals Occurrence of cross-resistance and beta-lactam seesaw effect in glycopeptide, lipopeptide, and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels

2019 ◽  
Author(s):  
Kelly M. Hines ◽  
Tianwei Shen ◽  
Nate K. Ashford ◽  
Adam Waalkes ◽  
Kelsi Penewit ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Membrane Lipid ◽  
Cross Resistance ◽  
Membrane Composition ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Penicillin Binding Proteins ◽  
Mrsa Strains ◽  
The Relationship

ABSTRACTTreatment of methicillin-resistantStaphylococcus aureus(MRSA) infections is challenging and is associated with high rates of therapeutic failure. The glycopeptide (GP) vancomycin and the lipopeptide (LP) daptomycin are still relied upon to manage invasive MRSA infections; however, resistance to these antibiotics has emerged and there is evidence of cross-resistance between them. It has been observed that the susceptibility of MRSA to beta-lactams increases as susceptibility to GPs and LPs decreases, a phenomenon termed the seesaw effect. Recent efforts to understand the mechanism underlying the seesaw effect have focused on the penicillin binding proteins (PBPs). However, while daptomycin resistance is largely mediated by remodeling of membrane lipid composition, the role of membrane lipids in producing cross-resistance and the seesaw effect has not yet been investigated. Here, we evaluate the lipid profiles, cross susceptibilities, and beta-lactam susceptibilities of a collection of isogenic MRSA strains selected against daptomycin, vancomycin or dalbavancin (a lipoglycopeptide; LGP) to assess the relationship between membrane composition, cross-resistance, and the seesaw effect. We found that modification of membrane composition occurs not only in daptomycin-selected strains, but also vancomycin- and dalbavancin-selected strains. Significantly, we observed that typically the levels of short-chain phosphatidylglycerols (PGs) negatively correlate with MICs of GP/LP/LGP and positively correlate with MIC of certain beta-lactams, the latter being dependent on the primary PBP target of the particular beta-lactam. Furthermore, changes to certain PGs with long-chain fatty acids correlate well with presence of the seesaw effect. These studies demonstrate a major association between membrane remodeling and the seesaw effect.

Dietary Selenium or Zinc Supplementation Restores Brain Lipid Composition and Membrane Fluidity in Protein-Undernourished Rats

2016 ◽  
Vol 38 (6) ◽  
pp. 397-406
Author(s):  
Olusegun L. Adebayo ◽  
Bamidele A. Salau ◽  
Rajat Sandhir ◽  
Gbenga A. Adenuga
Keyword(s):  
Membrane Fluidity ◽  
Lipid Composition ◽  
Zinc Supplementation ◽  
Protective Role ◽  
Membrane Lipid ◽  
Limited Information ◽  
Total Lipids ◽  
Major Focus ◽  
Membrane Lipid Composition

Studies have shown that protein undernutrition (PU) modifies the membrane lipid composition in the intestine and liver, as well as in plasma and other areas. However, there is limited information on the effect of PU on synaptosomal membrane lipid composition and fluidity and the protective role of selenium (Se) and zinc (Zn), which is a major focus of the present study. For 10 weeks, rats were fed diets containing 16% casein, which constituted the adequate protein diet, or 5% casein, representing the PU diet. The animals were supplemented with Se and Zn at a concentration of 0.15 and 227 mg L-1, respectively, in drinking water for 3 weeks. The results showed a significant increase in total lipids, glycolipids, triglycerides, cholesterol, and the cholesterol/phospholipid (Chol/PL) ratio, and a significant reduction in phospholipids and membrane fluidity. Se and Zn supplementation to PU rats, however, significantly lowered total lipids, glycolipids, triglycerides, cholesterol, and the Chol/PL ratio, while phospholipids and membrane fluidity were significantly restored. It is concluded that a perturbed lipid composition induced by PU affects the membrane structure and fluidity, which in turn influences membrane functions. The study suggests that Se and Zn supplementation might be beneficial in restoring the lipid dyshomeostasis associated with PU.

Regulation of TRPV5 and TRPV6 by associated proteins

2006 ◽  
Vol 290 (6) ◽  
pp. F1295-F1302 ◽  
Author(s):  
Stan F. J. van de Graaf ◽  
Joost G. J. Hoenderop ◽  
René J. M. Bindels
Keyword(s):  
Molecular Mechanisms ◽  
Hormonal Control ◽  
Trp Channel ◽  
Intestinal Lumen ◽  
Blood Compartment ◽  
Associated Proteins ◽  
The Relationship ◽  
Insight Into ◽  
Prime Target

The epithelial Ca2+ channels TRPV5 and TRPV6 are the most Ca2+-selective members of the TRP channel superfamily. These channels are the prime target for hormonal control of the active Ca2+ flux from the urine space or intestinal lumen to the blood compartment. Insight into their regulation is, therefore, pivotal in our understanding of the (patho)physiology of Ca2+ homeostasis. The recent elucidation of TRPV5/6-associated proteins has provided new insight into the molecular mechanisms underlying the regulation of these channels. In this review, we describe the various means of TRPV5/6 regulation, the role of channel-associated proteins herein, and the relationship between both processes.

scholarly journals Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling

2019 ◽  
Vol 116 (50) ◽  
pp. 25106-25114 ◽  
Author(s):  
Wenqian Li ◽  
Jun Yan ◽  
Yan Yu
Keyword(s):  
Immune Responses ◽  
Immune Regulation ◽  
Spatial Organization ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Membrane Composition ◽  
Intracellular Compartments ◽  
Synergistic Regulation ◽  
The Relationship

Receptors of innate immune cells function synergistically to detect pathogens and elicit appropriate immune responses. Many receptor pairs also appear “colocalized” on the membranes of phagosomes, the intracellular compartments for pathogen ingestion. However, the nature of the seemingly receptor colocalization and the role it plays in immune regulation are unclear, due to the inaccessibility of intracellular phagocytic receptors. Here, we report a geometric manipulation technique to directly probe the role of phagocytic receptor “colocalization” in innate immune regulation. Using particles with spatially patterned ligands as phagocytic targets, we can decouple the receptor pair, Dectin-1 and Toll-like receptor (TLR)2, to opposite sides on a single phagosome or bring them into nanoscale proximity without changing the overall membrane composition. We show that Dectin-1 enhances immune responses triggered predominantly by TLR2 when their centroid-to-centroid proximity is <500 nm, but this signaling synergy diminishes upon receptor segregation beyond this threshold distance. Our results demonstrate that nanoscale proximity, not necessarily colocalization, between Dectin-1 and TLR2 is required for their synergistic regulation of macrophage immune responses. This study elucidates the relationship between the spatial organization of phagocytic receptors and innate immune responses. It showcases a technique that allows spatial manipulation of receptors and their signal cross-talk on phagosomes inside living cells.

scholarly journals P4-199: Role of γ secretase in the cellular membrane lipid composition

2008 ◽  
Vol 4 ◽  
pp. T729-T730
Author(s):  
Jessica Hommes ◽  
Jochen Walter ◽  
Bernadette Breiden ◽  
Irfan Y. Tamboli ◽  
Günter Schwarzmann
Keyword(s):  
Lipid Composition ◽  
Cellular Membrane ◽  
Membrane Lipid ◽  
Membrane Lipid Composition

scholarly journals Direct and indirect interactions promote complexes of the lipoprotein LbcA, the CtpA protease and its substrates, and other cell wall proteins in Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Dolonchapa Chakraborty ◽  
Andrew J. Darwin
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Protein Complexes ◽  
Associated Proteins ◽  
Carboxyl Terminal ◽  
Multiple Species ◽  
Processing Protease ◽  
Enzyme Complexes

The Pseudomonas aeruginosa lipoprotein LbcA was discovered because it copurified with and promoted the activity of CtpA, a carboxyl-terminal processing protease (CTP) required for type III secretion system function, and for virulence in a mouse model of acute pneumonia. In this study we explored the role of LbcA by determining its effect on the proteome and its participation in protein complexes. lbcA and ctpA null mutations had strikingly similar effects on the proteome, suggesting that assisting CtpA might be the most impactful role of LbcA in the bacterial cell. Independent complexes containing LbcA and CtpA, or LbcA and substrate, were isolated from P. aeruginosa cells, indicating that LbcA facilitates proteolysis by recruiting the protease and its substrates independently. An unbiased examination of proteins that copurified with LbcA revealed an enrichment for proteins associated with the cell wall. One of these copurification partners was found to be a new CtpA substrate, and the first substrate that is not a peptidoglycan hydrolase. Many of the other LbcA copurification partners are known or predicted peptidoglycan hydrolases. However, some of these LbcA copurification partners were not cleaved by CtpA, and an in vitro assay revealed that while CtpA and all of its substrates bound to LbcA directly, these non-substrates did not. Subsequent experiments suggested that the non substrates might co-purify with LbcA by participating in multi-enzyme complexes containing LbcA-binding CtpA substrates. IMPORTANCE Carboxyl-terminal processing proteases (CTPs) are widely conserved and associated with the virulence of several bacteria, including CtpA in Pseudomonas aeruginosa . CtpA copurifies with the uncharacterized lipoprotein, LbcA. This study shows that the most impactful role of LbcA might be to promote CtpA-dependent proteolysis, and that it achieves this as a scaffold for CtpA and its substrates. It also reveals that LbcA copurification partners are enriched for cell wall-associated proteins, one of which is a novel CtpA substrate. Some of the LbcA copurification partners are not cleaved by CtpA, but might copurify with LbcA because they participate in multi-enzyme complexes containing CtpA substrates. These findings are important, because CTPs and their associated proteins affect peptidoglycan remodeling and virulence in multiple species.

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