Poly(arabitol phosphate) teichoic acid in the cell wall of Agromyces cerinus subsp. cerinus VKM Ac-1340T

Transport and Catabolism of Pentitols by Listeria monocytogenes

Transposon insertion into Listeria monocytogenes lmo2665, which encodes an EIIC of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS), was found to prevent D-arabitol utilization. We confirm this result with a deletion mutant and show that Lmo2665 is also required for D-xylitol utilization. We therefore called this protein EIICAxl. Both pentitols are probably catabolized via the pentose phosphate pathway (PPP) because lmo2665 belongs to an operon, which encodes the three PTSAxl components, two sugar-P dehydrogenases, and most PPP enzymes. The two dehydrogenases oxidize the pentitol-phosphates produced during PTS-catalyzed transport to the PPP intermediate xylulose-5-P. L. monocytogenes contains another PTS, which exhibits significant sequence identity to PTSAxl. Its genes are also part of an operon encoding PPP enzymes. Deletion of the EIIC-encoding gene (lmo0508) affected neither D-arabitol nor D-xylitol utilization, although D-arabitol induces the expression of this operon. Both operons are controlled by MtlR/LicR-type transcription activators (Lmo2668 and Lmo0501, respectively). Phosphorylation of Lmo0501 by the soluble PTSAxl components probably explains why D-arabitol also induces the second pentitol operon. Listerial virulence genes are submitted to strong repression by PTS sugars, such as glucose. However, D-arabitol inhibited virulence gene expression only at high concentrations, probably owing to its less efficient utilization compared to glucose.

Reclassification of Agromyces fucosus subsp. hippuratus as Agromyces hippuratus sp. nov., comb. nov. and emended description of Agromyces fucosus

The taxonomic position of Agromyces fucosus subsp. hippuratus is revised on the basis of molecular and phenotypic data. Phylogenetic analysis based on 16S rRNA gene sequences, DNA–DNA relatedness values and differences from other species in phenotypic traits revealed in this and earlier studies suggested reclassification of A. fucosus subsp. hippuratus as a separate species, Agromyces hippuratus sp. nov., comb. nov. The type strain is VKM Ac-1352T (=JCM 9087T). An emended description of Agromyces fucosus is given.

A continuum of anionic charge: structures and functions of D-alanyl-teichoic acids in gram-positive bacteria

Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and D-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with D-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of D-alanyl-TAs, the D-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of D-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of D-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to D-alanyl-TA synthesis.

Cell wall teichoic acids: structural diversity, species specificity in the genusNocardiopsis, and chemotaxonomic perspective

Data on the structures of cell wall teichoic acids, the anionic carbohydrate-containing polymers, found in many Gram-positive bacteria have been summarized and the polymers of the actinomycete genus Nocardiopsis have been considered from the taxonomic standpoint. The structures of these polymers or their combinations have been demonstrated to be indicative of each of seven Nocardiopsis species and two subspecies, verified by the DNA-DNA relatedness data, and to correlate well with the grouping of the organisms based on 16S rDNA sequences. As each of the intrageneric taxa discussed is definable by the composition of teichoic acids, the polymers are considered to be valuable taxonomic markers for the Nocardiopsis species and subspecies. The (13)C NMR spectra of the polymers, data on the products of their chemical degradation, and distinguishing constituents of whole cell walls derived from teichoic acids are discussed, which are useful for identification of certain polymers and members of the genus Nocardiopsis at the species and subspecies level in microbiological practice.

Structural investigations on the cell surface of Erysipelothrix rhusiopathiae

The cell wall of Erysipelothrix rhusiopathiae was investigated. The corrected structure of the murein, which was published earlier, is reported here. The murein belongs to the B1delta type. It has L-alanine in position three of the peptide subunit and is crosslinked via a glycine-L-lysine-L-lysine interpeptide bridge. As expected by the complex serological situation in E. rhusiopathiae the carbohydrate moiety of the cell wall proofed to be very intricate. As accessory polymers polysaccharide(s) and teichoic acid(s) were identified. The teichoic acid(s) possess two novel polyols of which one could not be identified, the other one behaved like 6-O-methylgalactitol in gas liquid chromatography. Glucose and N-acetylgalactosamine were determined as substituents. The polysaccharide(s) is composed of mainly N-acetylfucosamine and smaller amounts of galactose, N-acetylglucosamine, and a further unidentified sugar appearing later than hexaacetylsorbitol in GLC.