Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studied was the effect of some physical and chemical factors--heating, acidity, treatment with ultraviolet rays, and enzyme treatment--on the activity of the Brucella abortus 99 cell wall antigen. The activity of the antigen was determined through the microreaction of complement-fixing after Kolmer. It was found that the antigen was most sensitive to acid treatment and treatment with ultraviolet rays, and was more slightly sensitive to the effect of alkaline agents and pronase. Besides, the antigen proved heat-resistant and did not lose its activity after treatment with trypsin and alph- and beta-amylase. The chemical nature of the epitopes (the determinant groups), substantiating the activity of the antigen is briefly discussed.
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PMID:[Effect of physical and chemical factors on the antigenic activity of the cell walls of Brucella abortus 99]. 3 83

The structure of the lipid A from Rhizobium etli and Rhizobium leguminosarum lipopolysaccharides (LPSs) lacks phosphate and contains a galacturonosyl residue at its 4' position, an acylated 2-aminogluconate in place of the proximal glucosamine, and a very long chain omega-1 hydroxy fatty acid, 27-hydroxyoctacosanoic acid (27OHC28:0). The 27OHC28:0 moiety is common in lipid A's among members of the Rhizobiaceae and also among a number of the facultative intracellular pathogens that form chronic infections, e.g., Brucella abortus, Bartonella henselae, and Legionella pneumophila. In this paper, a mutant of R. leguminosarum was created by placing a kanamycin resistance cassette within acpXL, the gene which encodes the acyl carrier protein for 27OHC28:0. The result was an LPS containing a tetraacylated lipid A lacking 27OHC28:0. A small amount of the mutant lipid A may contain an added palmitic acid residue. The mutant is sensitive to changes in osmolarity and an increase in acidity, growth conditions that likely occur in the nodule microenvironment. In spite of the probably hostile microenvironment of the nodule, the acpXL mutant is still able to form nitrogen-fixing root nodules even though the appearance and development of nodules are delayed. Therefore, it is possible that the acpXL mutant has a host-inducible mechanism which enables it to adapt to these physiological changes.
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PMID:A Rhizobium leguminosarum AcpXL mutant produces lipopolysaccharide lacking 27-hydroxyoctacosanoic acid. 1261 48

The brucellae are facultative intracellular pathogens of mammals that are transmitted by contact with infected animals or contaminated materials. Several major lipidic components of the brucella cell envelope are imperfectly recognized by innate immunity, thus contributing to virulence. These components carry large proportions of acyl chains of lactobacillic acid, a long chain cyclopropane fatty acid (CFA). CFAs result from addition of a methylene group to unsaturated acyl chains and contribute to resistance to acidity, dryness and high osmolarity in many bacteria and to virulence in mycobacteria. We examined the role of lactobacillic acid in Brucella abortus virulence by creating a mutant in ORF BAB1_0476, the putative CFA synthase gene. The mutant did not incorporate [(14)C]methyl groups into lipids, lacked CFAs and synthesized the unsaturated precursors, proving that BAB1_0476 actually encodes a CFA synthase. BAB1_0476 promoter-luxAB fusion studies showed that CFA synthase expression was promoted by acid pH and high osmolarity. The mutant was not attenuated in macrophages or mice, strongly suggesting that CFAs are not essential for B. abortus intracellular life. However, when the mutant was tested under high osmolarity on agar and acid pH, two conditions likely to occur on contaminated materials and fomites, they showed reduced ability to grow or survive. Since CFA synthesis entails high ATP expenses and brucellae produce large proportions of lactobacillic acyl chains, we speculate that the CFA synthase has been conserved because it is useful for survival extracellularly, thus facilitating persistence in contaminated materials and transmission to new hosts.
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PMID:Identification and functional analysis of the cyclopropane fatty acid synthase of Brucella abortus. 2226 2