Physiological characterization of Streptococcus bovis mutants that can resist 2-deoxyglucose-induced lysis

Streptococcus bovis JB1 does not normally lyse, but stationary phase lysis can be induced by including 2-deoxyglucose (2DG) in the growth medium. Isol ates deficient in glucose/2DG phosphotransferase activity (PTS-) also lysed when 2DG was present (Lys(+)) and this result indicated that 2DG phosphory lation via the PTS was not an obligate requirement for 2DG-induced lysis, C ells and cell walls from 2DG-grown cultures lysed faster when proteinase K was added, but glucose-grown cultures and cell walls were not affected. A l ipoteichoic acid (LTA) extract (aqueous phase from hot phenol treatment) fr om glucose-grown cells inhibited the lysis of 2DG-grown cultures, but a sim ilar extract prepared from 2DG-grown cells was without effect. Thin-layer c hromatography and differential staining indicated that wild-type and Lys(+) PTS- cells incorporated 2DG into LTA, but lysis-resistant cultures (Lys(-) PTS+ and Lys(-) PTS-) did not. LTA from lysis-resistant (Lys(-) PTS+ and L ys(-) PTS-) cells grown with glucose and 2DG also prevented 2DG-dependent l ysis of the wild-type. LTA could not inhibit degradation of cell walls isol ated from 2DC-grown cultures, but LTA inhibited the lysis of Micrococcus ly sodeikticus (Micrococcus luteus) cells that were exposed to supernatants fr om 2DG-grown S. bovis cultures. Group D streptococci (including S. bovis) n ormally have an alpha-1,2 linked glucose disaccharide (kojibiose) in their LTA, but kojibiose cannot be synthesized from 2DG, This observation suggest ed that the kojibiose moiety of LTA was involved in autolysin inactivation. Wild-type S, bovis had ATP- as well as PEP-dependent mechanisms of 2DG pho sphorylation and one lysis-resistant phenotype (Lys(-) PTS-) had reduced le vels of both activities. However, the Lys(-) PTS+ phenotype was still able to phosphorylate 2DG via ATP and PEP and this result indicated that some ot her step of 2DG incorporation into LTA was being inhibited. Based on these results, growth in the presence of 2DG appears to prevent synthesis of norm al LTA, which is involved in the regulation of autolytic enzymes.