ABSTRACT
Chemical analyses, NMR spectroscopy, and mass spectrometry were used to elucidate the structure of the rough lipopolysaccharide (LPS) isolated from Acinetobacter lwoffii F78. As a prominent feature, the core region of this LPS contained the disaccharide alpha-Kdo-(2-->8)-alpha-Kdo (Kdo=3-deoxy-d-D-manno-oct-2-ulopyranosonic acid), which so far has been identified only in chlamydial LPS. In serological investigations, the anti-chlamydial LPS monoclonal antibody S25-2, which is specific for the epitope alpha-Kdo-(2-->8)-alpha-Kdo, reacted with A. lwoffii F78 LPS. Thus, an LPS was identified outside Chlamydiaceae that contains a Chlamydia-specific LPS epitope in its core region.
Subject(s)
Acinetobacter calcoaceticus/chemistry , Chlamydia/immunology , Chlamydiaceae/chemistry , Epitopes/immunology , Lipopolysaccharides/chemistry , Lipopolysaccharides/immunology , Chromatography, Thin Layer , Immunochemistry , Lipopolysaccharides/isolation & purification , Magnetic Resonance Spectroscopy , Molecular Structure , Oligosaccharides/chemistry , Spectrometry, Mass, Electrospray Ionization , Spectroscopy, Fourier Transform Infrared , Tandem Mass SpectrometryABSTRACT
For most prokaryotic organisms, amino acid biosynthesis represents a significant portion of their overall energy budget. The difference in the cost of synthesis between amino acids can be striking, differing by as much as 7-fold. Two prokaryotic organisms, Escherichia coli and Bacillus subtilis, have been shown to preferentially utilize less costly amino acids in highly expressed genes, indicating that parsimony in amino acid selection may confer a selective advantage for prokaryotes. This study confirms those findings and extends them to 4 additional prokaryotic organisms: Chlamydia trachomatis, Chlamydophila pneumoniae AR39, Synechocystis sp. PCC 6803, and Thermus thermophilus HB27. Adherence to codon-usage biases for each of these 6 organisms is inversely correlated with a coding region's average amino acid biosynthetic cost in a fashion that is independent of chemoheterotrophic, photoautotrophic, or thermophilic lifestyle. The obligate parasites C. trachomatis and C. pneumoniae AR39 are incapable of synthesizing many of the 20 common amino acids. Removing auxotrophic amino acids from consideration in these organisms does not alter the overall trend of preferential use of energetically inexpensive amino acids in highly expressed genes.
Subject(s)
Adaptation, Biological , Bacterial Proteins/genetics , Codon , Energy Metabolism , Genome, Bacterial , Amino Acids , Bacillus subtilis/chemistry , Bacillus subtilis/genetics , Bacterial Proteins/chemistry , Base Composition , Bias , Chlamydiaceae/chemistry , Chlamydiaceae/genetics , Escherichia coli/chemistry , Escherichia coli/genetics , Protein Biosynthesis , Selection, Genetic , Synechocystis/chemistry , Synechocystis/genetics , Thermus thermophilus/chemistry , Thermus thermophilus/geneticsABSTRACT
The antigen-binding fragments (Fab) of two murine monoclonal antibodies (mAb) S25-2 and S45-18, specific for carbohydrate epitopes in the lipopolysacchaide of the bacterial family Chlamydiaceae, have been crystallized in the presence and absence of synthetic oligosaccharides corresponding to their respective haptens. Crystals of both Fabs show different morphology depending on the presence of antigens. The sequence of mAb S45-18 was determined and shows a remarkable homology to that reported for mAb S25-2. These crystals offer an unparalleled opportunity to compare the structure and modes of binding of two homologous antibodies to similar but distinct carbohydrate epitopes.
