Iso- and anteiso-fatty acids in bacteria: biosynthesis, function, and taxonomic significance.

Manual for the Identification of Medical Bacteria.

The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of leaf microbial communities, with emphasis on Pseudomonas syringae—a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. Among the diversity of bacteria that colonize leaves, none has received wider attention than P. syringae, as it gained notoriety for being the first recombinant organism (Ice− P. syringae) to be deliberately introduced into the environment. We focus on P. syringae to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions. Leaf ecosystems are dynamic and ephemeral. The physical environment surrounding phyllosphere microbes changes continuously with daily cycles in temperature, radiation, relative humidity, wind velocity, and leaf wetness. Slightly longer-term changes occur as weather systems pass. Seasonal climatic changes impose still a longer cycle. The physical and physiological characteristics of leaves change as they expand, mature, and senesce and as host phenology changes. Many of these factors influence the development of populations of P. syringae upon populations of leaves. P. syringae was first studied for its ability to cause disease on plants. However, disease causation is but one aspect of its life strategy. The bacterium can be found in association with healthy leaves, growing and surviving for many generations on the surfaces of leaves as an epiphyte. A number of genes and traits have been identified that contribute to the fitness of P. syringae in the phyllosphere. While still in their infancy, such research efforts demonstrate that the P. syringae-leaf ecosystem is a particularly attractive system with which to bridge the gap between what is known about the molecular biology of genes linked to pathogenicity and the ecology and epidemiology of associated diseases as they occur in natural settings, the field.

Bacteria in the leaf ecosystem with emphasis on Pseudomonas syringae-a pathogen, ice nucleus, and epiphyte.

(1990). The Shikimate Pathway — A Metabolic Tree with Many Branche. Critical Reviews in Biochemistry and Molecular Biology: Vol. 25, No. 5, pp. 307-384.

The shikimate pathway―a metabolic tree with many branches

Biochemistry and Molecular Biology The Shikimate Pathway - A Metabolic Tree with Many Branches

The bfmB muant of Bacillus subtilis requires branched short-chain carboxylic acids for growth because the organism is known to be defective in branced-chain α-oxo acid dehydrogenase. The DNA in the region of bfmB has now been cloned and sequenced, and the gene has been analyzed. The results show that there are three open reading frames in the area, each of which is preceded by a putative ribosome binding site, and the last of which is followed by a putative transcription termination site with inverted repeats. The amino acid sequences deduced by analysis of the reading frames are highly similar (with 32–49% identity) to the E1α, E1β and E2 components of pyruvate, 2-oxoglutarate and branched-chain α-oxo acid dehydrogenases from different sources. The thiamin diphosphate binding, putative subunit interaction and phosphorylation sites of the E1α of four reported branched-chain α-oxo acid dehydrogenases from different sources are very similar to those of the first open reading frame (E1α) of bfmB. A similar result is also obtained with the lipoylbinding site (lysine) and its domain of the E2 component of α-oxo acid dehydrogenases from different sources. The present data, along with the reported biochemical data, lead to the conclusion that bfmB encodes a branched-chain α-oxo acid dehydrogenase, which is composed of E1α, E1β and E2 genes. This organization is identical to that of the 2-oxoglutarate dehydrogenase in B. subtilis.

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1432-1033.1993.tb17858.x

The primary structure of branched-chain α-oxo acid dehydrogenase from Bacillus subtilis and its similarity to other α-oxo acid dehydrogenases

Positional preference of fatty acids in phospholipids of Bacillus cereus and its relation to growth temperature.

Fatty acid compositions of lipids from six bacteria and four yeasts were determined. Fatty acid de novo synthetases were investigated with respect to chain length specificity towards acyl-CoA primers of various chain lengths. Four species of bacteria (Bacillus subtilis, Corynebacterium cyclohexanicum, Micrococcus luteus, and Pseudomonas maltophilia) possess branched-chain fatty acids of the iso and anteiso series as the major acids. De novo synthetases from these organisms exhibited specificity towards the chain length of the primer in the order butyl-CoA > priopionyl-CoA > acetyl-CoA. The remainder, two bacteria and all four yeasts, have the straight-chain type of fatty acids only and fall into two groups: (1) Eschericia coli B, Pseudomonas fluorescens, and Saccharomyces cerevisiae, which utilize the primers in the order acetyl-CoA > priopionyl-CoA > butyryl-CoA; and (2) Candida sake, Candida tropicalis, and Rhodotorula glutinis, which show the order propionyl-CoA > acetyl-CoA > butyryl-CoA. L-alpha-Keto-beta-methylvalerate, a precursor of the branched-chain primers, can be used as a source of primer for fatty acid synthesis by the organisms with branched-chain acids but not by those with the straight-chain type. The results indicate that organisms having straight-chain fatty acids lack the branched-chain equivalents for two reasons: first, their enzymes are not active toward primers with more than three carbons, and second, they lack a system of supply suitable branched-chain primers. It appears that activities of de novo synthetases from the organisms having straight-chain fatty acids generally have much higher activities than those from the organisms possessing branched-chain fatty acids

Relationship of primer specificity of fatty acid de novo synthetase to fatty acid composition in 10 species of bacteria and yeasts.

Valine as a source of the branched short chain precursor in the biosynthesis of iso-C14, iso-C15, iso-C16 and iso-C17 fatty acids by Bacillus, subtilis

Toshi Kaneda

Papers

The primary structure of branched-chain α-oxo acid dehydrogenase from Bacillus subtilis and its similarity to other α-oxo acid dehydrogenases

Positional preference of fatty acids in phospholipids of Bacillus cereus and its relation to growth temperature.

Relationship of primer specificity of fatty acid de novo synthetase to fatty acid composition in 10 species of bacteria and yeasts.

Valine as a source of the branched short chain precursor in the biosynthesis of iso-C14, iso-C15, iso-C16 and iso-C17 fatty acids by Bacillus, subtilis

Biosynthesis of branched-chain fatty acids. V. Microbial stereospecific syntheses of D-12-methyltetradecanoic and D-14-methylhexadecanoic acids.