Possible role of a choline-containing teichoic acid in the maintenance of normal cell shape and physiology in Streptococcus oralis

Abstract

Streptococcus oralis ATCC 35037 took up radioactively labeled choline from growth medium. Most of the choline (80 to 90%o) was incorporated into the cell wall teichoic acid, and about 10%Y was localized in the plasma membrane. While cells grew in choline-free medium, they did so at slow rates and produced cell walls with greatly reduced amounts of phosphate and no detectable choline. Cells grown in choline-free medium had grossly abnormal shape and size. Both biochemical and morphological abnormalities were reversible by addition of choline to the medium.Teichoic acids, complex anionic wall polymers ubiquitous in gram-positive bacteria (30,31), are known to have important ecological roles such as receptors for bacteriophage (1), as type-or group-specific antigens (7), and as reservoirs of surface-bound divalent cations (2, 31). Structurally similar so-called membrane teichoic acid polymers linked to glycolipids are also present in smaller quantities in the plasma membrane of all gram-positive bacteria. The precise physiological role(s) of these wall-and membrane-linked polymers in bacterial growth remains to be determined. Cell wall teichoic acids play a role in cellular morphogenesis in Bacillus subtilis and Bacillus licheniformis (3, 9, 10,22), and genetic studies with teichoic acid mutants ofB. subtilis imply that these polymers are essential for normal cell growth (5,16,19). Amino alcohols (e.g., choline), which are unique components of both the wall and membrane teichoic acids of Streptococcus pneumoniae, are essential nutrients for this bacterium (2,27). Choline is also present in the wall teichoic acid of several viridans group streptococci and clostridia (20,24,26). Streptococcus oralis is frequently identified among viridans group streptococci that colonize human upper respiratory tracts (4,20). While closely related to S. pneumoniae, this bacterium is classified as a distinct species on the basis of nucleic acid hybridization and cell wall composition data (20,25,26).In preliminary studies with S. oralis ATCC 35037, it was noticed that omission of choline from a synthetic growth medium (28) caused striking abnormalities in the growth and morphology of these bacteria. In this communication, we describe an analysis of these phenomena. MATERIALS AND METHODSBacterial strains and culture conditions. S. oralis ATCC 35037 was cultivated in a chemically defined (CDen) medium, a synthetic medium (21) modified by replacing the Casamino Acid hydrolysate with a mixture of pure individual amino acids. The medium was modified as indicated in several experiments by omission of choline. Cultures of bacteria grown in choline-free medium were produced in the following manner. Bacteria grown in full (choline-contain-* Corresponding author. ing) medium were diluted 100-fold into choline-free medium and grown at 370C overnight, after which the culture was further diluted 10-to 20-fold into the same amino alcoholfree medium. The doubling time of cell mass was 1 h in the presence and about 2 to 2.5 h in the absence of cholin...

Shewanella pealeana sp. nov., a member of the microbial community associated with the accessory nidamental gland of the squid Loligo pealei

“…However, the synthesis of phosphatidylcholine by most prokaryotes for their membranes has not been demonstrated (Moat, 1979), suggesting that this possible use for choline is possible but unlikely. The growth of several Gram-positive organisms in the absence (Horne & Tomasz, 1993) or in an excess (Podvin et al, 1988) of choline was shown to result in severely affected cell shape, cell division and overall physiology. Perhaps a high choline content in the yeast extract of LB affected ANG-SQIT, leading to celldivision defects (data not shown) and eventual cell death.…”

The pgdA Gene Encodes for a PeptidoglycanN-Acetylglucosamine Deacetylase in Streptococcus pneumoniae

“…Bacterial Strains, Plasmids, and Growth Media-Cultures of S. pneumoniae R36A, a non-encapsulated laboratory strain from the Rockefeller University collection, were grown in a casein-based semi-synthetic medium (C ϩ Y) containing 1 mg/ml yeast extract (7) or in a chemically defined medium (Cden) (8) at 37°C without aeration. Plasmid pJDC9 (9) was used for insertion duplication mutagenesis.…”

Mutations in thetacFGene of Clinical Strains and Laboratory Transformants ofStreptococcus pneumoniae:Impact on Choline Auxotrophy and Growth Rate

“…Unlike the pneumococcus, however, S. oralis has no nutritional requirement for choline and when grown in its absence, PChofree TA seems to be incorporated into the cell wall, although the cells show a grossly abnormal shape and size (16). That is, in contrast to the uniform size of normal cells, choline-free bacteria showed a wide distribution of sizes.…”