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E W Goodell

Publications and source records attributed to E W Goodell.

13 recordsLinked to original sources
PubMed1991

Direct proof of a "more-than-single-layered" peptidoglycan architecture of Escherichia coli W7: a neutron small-angle scattering study.

A neutron small-angle scattering study was performed to determine the thickness and the scattering density profile of isolated peptidoglycan sacculi of Escherichia coli W7 in aqueous suspension (D2O). The maximum thickness (7 +/- 0.5 nm) of the sacculus from the exponential-phase cells was large enough to suggest the existence of a more-than-single-layered architecture. The experimental density profile across the thickness of the sacculus did not allow an unambiguous differentiation between a single-layered architecture characterized by completely extended peptide side chains projecting from the sugar strands or, alternatively, a partially triple layered structure. To resolve this ambiguity, sacculi were labeled with deuterated wall peptides. Comparison of the two experimental profiles indicated that the sacculus is more than single layered across its surface, with about 75 to 80% of its surface single layered and 20 to 25% triple layered.

Escherichia coli↗
PubMed1990

Cloning and characterization of mepA, the structural gene of the penicillin-insensitive murein endopeptidase from Escherichia coli.

The putative structural gene mepA of the penicillin-insensitive murein endopeptidase from Escherichia coli was cloned and sequenced. N-terminal sequence determination with the isolated endopeptidase protein showed that this enzyme is coded by the mepA gene and that it is synthesized initially with an N-terminal signal peptide. No significant sequence homology with the other (penicillin-sensitive) murein endopeptidase (dacB) or any other protein was found. The precise chromosomal mapping position of mepA relative to two other genes, aroC and fabB, was shown to be 50.4 min. E. coli strains carrying multicopy plasmids with the mepA gene produced 5-6-fold more endopeptidase and secreted it into the periplasm, where it appeared to function normally in vivo since the release of cell wall peptides into the medium increased in parallel. The transformed cells were, however, not unusually sensitive to penicillin and their murein had a normal degree of cross-bridges.

Amino Acid Sequence↗
PubMed1987

Uptake of cell wall peptides by Salmonella typhimurium and Escherichia coli.

During bacterial growth, cell wall peptides are released from the murein and reused for the synthesis of new cell wall material. Mutants defective in peptide transport were unable to reutilize cell wall peptides, demonstrating that these peptides are taken up intact into the cytoplasm prior to reincorporation into murein. Furthermore, cell wall peptide recycling was shown to play an important physiological role; peptide transport mutants which were unable to recycle these peptides showed growth defects under appropriate conditions. Using mutants specifically defective in each of the three peptide transport systems, we showed that the uptake of cell wall peptides was mediated solely by the oligopeptide permease (Opp) and that neither the dipeptide permease (Dpp) nor the tripeptide permease (Tpp) played a significant role in this process. Our data indicate that the periplasmic oligopeptide-binding protein has more than one substrate-binding site, each with different though overlapping specificities.

Bacterial Proteins↗
PubMed1985

Release of cell wall peptides into culture medium by exponentially growing Escherichia coli.

Escherichia coli W7 cells were found to release three different muropeptides into the culture medium: tetrapeptide (L-Ala-D-Glu-meso-diaminopimelic acid-D-Ala), tripeptide (L-Ala-D-Glu-meso-diaminopimelic acid), and a previously undescribed dipeptide (meso-diaminopimelic acid-D-Ala). From the rate of release of these three peptides, it was calculated that 6 to 8% of the murein in the sacculus was lost per generation.

Cell Survival↗
PubMed1985

Recycling of murein by Escherichia coli.

The tripeptide (L-Ala-D-Glu-meso-diaminopimelic acid [A2pm]), tetrapeptide (L-Ala-D-Glu-A2pm-D-Ala), and dipeptide (A2pm-D-Ala) which are shed by Escherichia coli from the murein sacculus were found to be reused by the cells to synthesize murein. The tripeptide was used directly, without degradation, to form UDP-N-acetylmuramyl-L-Ala-D-Glu-A2pm. The tetrapeptide lost its carboxy-terminal D-Ala, apparently in the periplasm, before being used. The dipeptide was degraded to D-Ala and A2pm before uptake.

Biological Transport↗
PubMed1978

Effect of benzylpenicillin on the synthesis and structure of the cell envelope of Neisseria gonorrhoeae.

The effect of benzylpenicillin on the synthesis and morphology of the cell envelope of Neisseria gonorrhoeae was examined. Penicillin immediately stopped murein synthesis; it also enhanced the rate of turnover of glucosamine, but not diaminopimelic acid, in the murein. In addition, penicillin greatly increased the shedding of lipid and lipopolysaccharide into the medium. In the electron microscope, protrusions of the cell membrane were evident, as well as apparent holes in the murein cell wall. All of these changes occurred while active synthesis was taking place, before the lysis of the cells. Lysis could be prevented by growing the cells at low pH and high concentrations of Mg2+; however, the effects of penicillin on murein synthesis and turnover and on the release of lipid were not affected.

Cell Membrane↗
PubMed1977

Enzymes synthesizing and hydrolyzing murein in Escherichia coli. Topographical distribution over the cell envelope.

Envelopes from regions of the cell which in vivo show very little, if any, murein synthesis were isolated using the minicell-producing strain P678-54. Envelopes from minicells, representing in fact cell ends, were able to synthesize murein and to carry out transpeptidation in vitro; also all four murein hydrolase activities tested, carboxypeptidase, endopeptidase, amidase and transglycosylase, were found to be present. The specific activities of the murein synthesizing and degrading enzymes in envelopes derived from cell poles and from actively growing cells were similar. The topological distribution of murein-synthesizing enzymes and of murein hydrolases over the cell envelope is discussed.

Amidohydrolases↗
PubMed1976

Suppression of lytic effect of beta lactams on Escherichia coli and other bacteria.

Growth of E. coli at pH 5 protected the bacteria against the lytic effect of beta lactam antibiotics typically observed when the cells are grown at pH 7 or 7.5, i.e., the pH values routinely used in laboratory experiments. In contrast, the typical effects of beta lactam antibiotics on cellular shape and elongation and cell division appeared to be similar in cultures grown under neutral and acid pH conditions. The pH-dependent antibiotic tolerance can also be demonstrated with pneumococci, staphylococci, streptococci, and Bacillus subtilis. We suggest that the mechanism of the pH-dependent antibiotic tolerance may involve either the production of a more stable plasma membrane or the suppression of the activity of a murein hydrolase(s) that catalyzes the antibiotic-induced lysis; at least a fraction of these enzyme molecules may be localized at the cell surface and be accessible to experimental manipulation.

Bacillus subtilis↗
PubMed1975

Sphere-rod morphogenesis of Escherichia coli.

The morphogenetic capacity of E. coli was studied by converting the rod-shaped cells into spheres and then determining whether these spheres could revert to rods. The morphogenesis of cells was followed by immobilizing them in a viscous Methocel-containing medium. Two different types of spheres were prepared: cells which retained a mechanically intact sacculus, and osmotically sensitive sphaeroplasts lacking a sacculus. The sphaeroplasts were not able to revert to rods although they were able to synthesize a new sacculus. In contrast, spheres which had retained an intact sacculus were able to reshape themselves into rods. The were also able to form new ends at (or near) the sites of the ends on the original rods.

Cell Wall↗
PubMed1969

Phycomyces.

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Cell Biology↗