Isolement et caractérisation chimique des lipopolysaccharides de type R dans une souche hypovirulente de Yersinia pestis

1998 ◽  
Vol 44 (5) ◽  
pp. 477-481 ◽  
Author(s):  
S Minka ◽  
M Bruneteau
Keyword(s):  
Biological Activity ◽  
Hydrochloric Acid ◽  
Yersinia Pestis ◽  
Primary Structure ◽  
Gel Electrophoresis ◽  
Lipid A ◽  
Solvent Mixture ◽  
Chloroform Methanol

The lipopolysaccharides LPS I and LPS II, isolated from the hypovirulent EV40 strain of Yersinia pestis, are composed only of type R lipopolysaccharides. This type consists of two forms, a and b, depending on their solubility pattern in a solvent mixture containing varying proportions of chloroform, methanol, hexane, and hydrochloric acid. LPS I consists of one subtype, RIb, while LPS II consists of two subtypes, RIIa and RIIb. Analysis by gel electrophoresis shows that the mass of these lipopolysaccharide forms are in the vicinity of 2000-3000 Da. The RIb and RIIb subtypes, which are found in the majority of lipopolysaccharide I and II fractions, are composed of ketoses and amines that are similar to those occurring in LPS I and LPS II. In contrast, the two subtypes RIIa and RIIb are different both in terms of the composition of lipid A and the extent of its substitution. Certain fractions of RIIa contain only lipid A and 3-deoxy-D-manno-octulosonic acid (KDO), while other fractions of RIIb possess a lipid A, which is not substituted by arabinose. The whole set of these R-type lipopolysaccharide forms are excellent models for the study of the role of the primary structure of the polysaccharide region, and for the effect of lipid A substitution on the biological activity of bacterial lipopolysaccharides.Key words: Yersinia pestis, hypovirulence, lipopolysaccharides, R type.[Journal translation]

Distinct biological activity of lipopolysaccharides with different lipid a acylation status from mutant strains of Yersinia pestis and some members of genus Psychrobacter

2014 ◽  
Vol 79 (12) ◽  
pp. 1333-1338 ◽  
Author(s):  
K. V. Korneev ◽  
A. N. Kondakova ◽  
N. P. Arbatsky ◽  
K. A. Novototskaya-Vlasova ◽  
E. M. Rivkina ◽  
...  
Keyword(s):  
Biological Activity ◽  
Yersinia Pestis ◽  
Lipid A ◽  
Mutant Strains

Biological activity of novel thyroid hormone analogues: role of Na+ taurocholate cotransporting polypeptide in liver selectivity

2015 ◽  
Author(s):  
Giulia Brigante ◽  
Bo Carlsson ◽  
Simone Kersseboom ◽  
Robin P Peeters ◽  
Theo J Visser
Keyword(s):  
Biological Activity ◽  
Thyroid Hormone

scholarly journals Studies on the Role of Methylated Bases in the Biological Activity of Soluble Ribonucleic Acid

1964 ◽  
Vol 239 (9) ◽  
pp. 2918-2926
Author(s):  
Alan Peterkofsky ◽  
Celia Jesensky ◽  
Arthur Bank ◽  
Alan H. Mehler
Keyword(s):  
Biological Activity ◽  
Ribonucleic Acid

scholarly journals Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata

2021 ◽  
Vol 22 (12) ◽  
pp. 6557
Author(s):  
Li-Ying Ren ◽  
Heng Zhao ◽  
Xiao-Ling Liu ◽  
Tong-Kai Zong ◽  
Min Qiao ◽  
...  
Keyword(s):  
Biological Activity ◽  
Abscisic Acid ◽  
Lignin Degradation ◽  
Molecular Mechanisms ◽  
Receptor Protein ◽  
Gastrodia Elata ◽  
Upregulated Genes ◽  
Aba Biosynthesis ◽  
Seed Coats

Gastrodia elata is a well-known medicinal and heterotrophic orchid. Its germination, limited by the impermeability of seed coat lignin and inhibition by abscisic acid (ABA), is triggered by symbiosis with fungi such as Mycena spp. However, the molecular mechanisms of lignin degradation by Mycena and ABA biosynthesis and signaling in G. elata remain unclear. In order to gain insights into these two processes, this study analyzed the transcriptomes of these organisms during their dynamic symbiosis. Among the 25 lignin-modifying enzyme genes in Mycena, two ligninolytic class II peroxidases and two laccases were significantly upregulated, most likely enabling Mycena hyphae to break through the lignin seed coats of G. elata. Genes related to reduced virulence and loss of pathogenicity in Mycena accounted for more than half of annotated genes, presumably contributing to symbiosis. After coculture, upregulated genes outnumbered downregulated genes in G. elata seeds, suggesting slightly increased biological activity, while Mycena hyphae had fewer upregulated than downregulated genes, indicating decreased biological activity. ABA biosynthesis in G. elata was reduced by the downregulated expression of 9-cis-epoxycarotenoid dioxygenase (NCED-2), and ABA signaling was blocked by the downregulated expression of a receptor protein (PYL12-like). This is the first report to describe the role of NCED-2 and PYL12-like in breaking G. elata seed dormancy by reducing the synthesis and blocking the signaling of the germination inhibitor ABA. This study provides a theoretical basis for screening germination fungi to identify effective symbionts and for reducing ABA inhibition of G. elata seed germination.

scholarly journals Differential Role of Threonine and Tyrosine Phosphorylation in the Activation and Activity of the Yeast MAPK Slt2

2021 ◽  
Vol 22 (3) ◽  
pp. 1110
Author(s):  
Gema González-Rubio ◽  
Ángela Sellers-Moya ◽  
Humberto Martín ◽  
María Molina
Keyword(s):  
Cell Wall ◽  
Biological Activity ◽  
Biological Significance ◽  
Mitogen Activated Protein Kinase ◽  
Activation Loop ◽  
High Increase ◽  
Dual Specificity ◽  
Mitogen Activated Protein ◽  
Full Activation

The Mitogen-Activated Protein Kinase (MAPK) Slt2 is central to signaling through the yeast Cell Wall Integrity (CWI) pathway. MAPKs are regulated by phosphorylation at both the threonine and tyrosine of the conserved TXY motif within the activation loop (T190/Y192 in Slt2). Since phosphorylation at both sites results in the full activation of MAPKs, signaling through MAPK pathways is monitored with antibodies that detect dually phosphorylated forms. However, most of these antibodies also recognize monophosphorylated species, whose relative abundance and functionality are diverse. By using different phosphospecific antibodies and phosphate-affinity (Phos-tag) analysis on distinct Slt2 mutants, we determined that Y192- and T190-monophosphorylated species coexist with biphosphorylated Slt2, although most of the Slt2 pool remains unphosphorylated following stress. Among the monophosphorylated forms, only T190 exhibited biological activity. Upon stimulation, Slt2 is first phosphorylated at Y192, mainly by the MAPKK Mkk1, and this phosphorylation is important for the subsequent T190 phosphorylation. Similarly, dephosphorylation of Slt2 by the Dual Specificity Phosphatase (DSP) Msg5 is ordered, with dephosphorylation of T190 depending on previous Y192 dephosphorylation. Whereas Y192 phosphorylation enhances the Slt2 catalytic activity, T190 is essential for this activity. The conserved T195 residue is also critical for Slt2 functionality. Mutations that abolish the activity of Slt2 result in a high increase in inactive Y192-monophosphorylated Slt2. The coexistence of different Slt2 phosphoforms with diverse biological significance highlights the importance of the precise detection of the Slt2 phosphorylation status.

Structural comparisons of pyrodextrins during thermal degradation process: The role of hydrochloric acid

2021 ◽  
Vol 349 ◽  
pp. 129174
Author(s):  
Huijia Mao ◽  
Zhijun Chen ◽  
Jie Li ◽  
Xueyang Zhai ◽  
Hongyan Li ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Thermal Degradation Process

scholarly journals Role of peptide backbone conformation on biological activity of chemotactic peptides.

1991 ◽  
Vol 266 (28) ◽  
pp. 18460-18468
Author(s):  
A.R. Dentino ◽  
P.A. Raj ◽  
K.K. Bhandary ◽  
M.E. Wilson ◽  
M.J. Levine
Keyword(s):  
Biological Activity ◽  
Peptide Backbone ◽  
Backbone Conformation ◽  
Chemotactic Peptides ◽  
Peptide Backbone Conformation
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