Why and how are peptide-lipid interactions utilized for self defence?

2001 ◽  
Vol 29 (4) ◽  
pp. 598-601 ◽  
Author(s):  
K. Matsuzaki
Keyword(s):  
Supramolecular Complex ◽  
Effective Mechanism ◽  
Bacterial Membranes ◽  
Lipid Interactions ◽  
Peptide Molecule ◽  
Transport Of Ions ◽  
Β Sheets ◽  
Micro Organisms ◽  
Microbial Action ◽  
Self Defence

Animals defend themselves against invading pathogenic micro-organisms by utilizing cationic anti-microbial peptides, which rapidly kill various micro-organisms without exerting toxicity against the host. Physicochemical peptide-lipid interactions provide attractive mechanisms for innate immunity. Many of these peptides form amphipathic secondary structures (α-helices and β-sheets) which can selectively interact with anionic bacterial membranes by electrostatic interaction. Rapid, peptide-induced membrane permeabilization is an effective mechanism of anti-microbial action. Magainin 2 from frog skin forms a dynamic peptide-lipid supramolecular-complex pore that allows mutually coupled transmembrane transport of ions and lipids. The peptide molecule is internalized upon the disintegration of the pore. Several anti-microbial peptides are known to work synergistically.

scholarly journals Structure of mushroom casing soil and its influence on yield and microflora.

1975 ◽  
Vol 23 (1) ◽  
pp. 36-47
Author(s):  
H.R. Visscher
Keyword(s):  
Vegetative Growth ◽  
Fruit Body ◽  
Soya Bean ◽  
Mushroom Compost ◽  
Bean Meal ◽  
Generative Phase ◽  
Soya Bean Meal ◽  
Micro Organisms ◽  
Microbial Action ◽  
Gaseous Metabolites

Mushroom yields were higher on more compact casing soil provided (1) a large amount of water was applied (in this case 7 litres/m2) and (2) the upper layer of the casing was ruffled or raked up before the start of the generative phase. Suppressing the diffusion of gaseous metabolites from compost to air during vegetative growth improved the yield provided a good diffusion of air is restored just prior to fructification. Many of the relevant phenomena can be attributed to CO2, but the effect of other metabolites such as acetone and ethylene on fruit body-inducing micro-organisms cannot be neglected. Microbial action appears to be involved in the stimulating effect of soya bean meal added to the mushroom compost. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Phosphatidylglyerol Lipid Binding at the Active Site of an Intramembrane Protease

2020 ◽  
Vol 253 (6) ◽  
pp. 563-576
Author(s):  
Ana-Nicoleta Bondar
Keyword(s):  
Active Site ◽  
Lipid Membranes ◽  
Lipid Binding ◽  
Rhomboid Protease ◽  
Bacterial Membranes ◽  
Lipid Interactions ◽  
Reaction Coordinates ◽  
Substrate Docking ◽  
Substrate Cleavage ◽  
Molecular Picture

AbstractTransmembrane substrate cleavage by the small Escherichia coli rhomboid protease GlpG informs on mechanisms by which lipid interactions shape reaction coordinates of membrane-embedded enzymes. Here, I review and discuss new work on the molecular picture of protein–lipid interactions that might govern the formation of the substrate–enzyme complex in fluid lipid membranes. Negatively charged PG-type lipids are of particular interest, because they are a major component of bacterial membranes. Atomistic computer simulations indicate POPG and DOPG lipids bridge remote parts of GlpG and might pre-occupy the substrate-docking site. Inhibition of catalytic activity by PG lipids could arise from ligand-like lipid binding at the active site, which could delay or prevent substrate docking. Dynamic protein–lipid H-bond networks, water access to the active site, and fluctuations in the orientation of GlpG suggest that GlpG has lipid-coupled dynamics that could shape the energy landscape of transmembrane substrate docking. Graphic Abstract

scholarly journals The specificity of combination between ristocetins and peptides related to bacterial cell wall mucopeptide precursors

1971 ◽  
Vol 124 (5) ◽  
pp. 845-852 ◽  
Author(s):  
M. Nieto ◽  
H. R. Perkins
Keyword(s):  
Cell Wall ◽  
Amino Acid ◽  
Bacterial Cell ◽  
Bacterial Cell Wall ◽  
Optical Rotatory Dispersion ◽  
Amino Acid Residues ◽  
Peptide Molecule ◽  
Micro Organisms ◽  
Specific Peptide ◽  
Absorption Characteristics

The affinity of ristocetin B for analogues of the C-terminal tripeptide sequence of bacterial cell wall mucopeptide precursors resembles that of vancomycin. Complex-formation requires a d-configuration in the two amino acid residues of the C-terminal dipeptide, an l-configuration is preferred in the preceding amino acid residue and positive charges on the peptide molecule decrease its affinity. The specificity of ristocetin B, however, differs from that of vancomycin in the requirements for the size of the side chains on the C-terminal dipeptide. These differences may explain the observed differences in antibiotic behaviour of vancomycin and ristocetin with particular micro-organisms. The optical rotatory dispersion and u.v.-absorption characteristics of the ristocetins are very different from those of vancomycin but nearly identical with those of ristomycin A. Aglycones prepared from ristomycin A were antibiotically active and also combined with a specific peptide.

scholarly journals Dihydrodipicolinate synthase is not inhibited by its substrate, (S)-aspartate beta-semialdehyde

2004 ◽  
Vol 377 (3) ◽  
pp. 757-762 ◽  
Author(s):  
Renwick C. J. DOBSON ◽  
Juliet A. GERRARD ◽  
F. Grant PEARCE
Keyword(s):  
Escherichia Coli ◽  
Lysine Biosynthesis ◽  
Dihydrodipicolinate Synthase ◽  
Micro Organisms ◽  
Microbial Action

DHDPS (dihydrodipicolinate synthase; EC 4.2.1.52) is the enzyme that catalyses the first unique step of lysine biosynthesis in plants and micro-organisms. As such, it has attracted much attention as a target for herbicide and anti-microbial action. DHDPS has two substrates: pyruvate and (S)-aspartate β-semialdehyde [(S)-ASA]. There are various literature reports that suggest that high levels of (S)-ASA inhibit the enzyme [Karsten (1997) Biochemistry 36, 1730–1739; Stahly (1969) Biochim. Biophys. Acta 191, 439–451], whereas others have not observed this phenomenon. We have resolved this long-running literature debate and shown unequivocally that this difference in reported behaviour can be attributed to differences in the preparation of (S)-ASA used by each researcher. DHDPS is not inhibited by its substrate; rather, the inhibition is due to an, as yet, unidentified inhibitor in preparations of the substrate generated by ozonolysis. Furthermore, we demonstrate that (R)-ASA is neither an inhibitor nor a substrate of DHDPS from Escherichia coli.

Review of the Radiation Damage Problem of Organic Specimens in Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 476-477
Author(s):  
L. Reimer
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Irradiation Time ◽  
Dose Effect ◽  
Primary Process ◽  
Thin Specimen ◽  
Secondary Damage ◽  
Small Doses ◽  
Micro Organisms ◽  
Damage Processes

Most information about a specimen is obtained by elastic scattering of electrons, but one cannot avoid inelastic scattering and therefore radiation damage by ionisation as a primary process of damage. This damage is a dose effect, being proportional to the product of lectron current density j and the irradiation time t in Coul.cm−2 as long as there is a negligible heating of the specimen.Therefore one has to determine the dose needed to produce secondary damage processes, which can be measured quantitatively by a chemical or physical effect in the thin specimen. The survival of micro-organisms or the decrease of photoconductivity and cathodoluminescence are such effects needing very small doses (see table).

Functional amyloid: widespread in Nature, diverse in purpose

2014 ◽  
Vol 56 ◽  
pp. 207-219 ◽  
Author(s):  
Chi L.L. Pham ◽  
Ann H. Kwan ◽  
Margaret Sunde
Keyword(s):  
Spider Silk ◽  
Epigenetic Inheritance ◽  
Fibrillar Structure ◽  
Cytoplasmic Polyadenylation ◽  
Functional Amyloid ◽  
Interacting Protein ◽  
Diverse Range ◽  
Element Binding Protein ◽  
Functional Amyloids ◽  
Micro Organisms

Amyloids are insoluble fibrillar protein deposits with an underlying cross-β structure initially discovered in the context of human diseases. However, it is now clear that the same fibrillar structure is used by many organisms, from bacteria to humans, in order to achieve a diverse range of biological functions. These functions include structure and protection (e.g. curli and chorion proteins, and insect and spider silk proteins), aiding interface transitions and cell–cell recognition (e.g. chaplins, rodlins and hydrophobins), protein control and storage (e.g. Microcin E492, modulins and PMEL), and epigenetic inheritance and memory [e.g. Sup35, Ure2p, HET-s and CPEB (cytoplasmic polyadenylation element-binding protein)]. As more examples of functional amyloid come to light, the list of roles associated with functional amyloids has continued to expand. More recently, amyloids have also been implicated in signal transduction [e.g. RIP1/RIP3 (receptor-interacting protein)] and perhaps in host defence [e.g. aDrs (anionic dermaseptin) peptide]. The present chapter discusses in detail functional amyloids that are used in Nature by micro-organisms, non-mammalian animals and mammals, including the biological roles that they play, their molecular composition and how they assemble, as well as the coping strategies that organisms have evolved to avoid the potential toxicity of functional amyloid.

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