Synth Pro4

Pedigree of the PBP deletion mutants. The chart reflects the order in which genes were deleted from each strain. The original parental background was E. coli CS109. Mutants from which a single gene was deleted have names with numbers in the teens; mutants from which two genes were deleted have names with numbers in the 200’s; mutants with three genes deleted are numbered in the 300’s, etc. In the chart, the strain number is given but the “CS” prefix for each strain name was omitted for clarity. Underneath the number of each strain is listed the PBP gene that was deleted from the preceding parent to create that strain. Therefore, to determine the total complement of genes that were deleted from a particular strain, simply move “upward,” following the arrows backward to the ultimate parent, CS109, noting which genes were deleted in that lineage. More strains are shown than the minimum 192 required to make all possible mutants because some combinations were constructed by deleting genes in different orders. The mutants are listed in numerical order in Table 1, which includes a list of the genes deleted from each strain.

Basic structures of β-lactam antibiotics. Penicillins and cephalosporins/cephamycins are widely used to inhibit both Gram-positive and Gram-negative bacilli. Monobactams inhibit only aerobic Gram-negative bacilli, clavulanic acid acts as a β-lactamase inhibitor, and thienamycin inhibits a wide range of aerobic and anaerobic species. R and R1 represent various carbon groups. X can be either hydrogen or a mehoxy group.

Proposed murein replicase holoenzyme in action. It is proposed that the multienzyme complex synthesizes three new murein strands (shown in grey), attaches these strands to the cross bridges on both sides of the docking strand (single grey strand), and at the same time degrades this strand by the concerted action of a processive lytic transglycosylase and a dimer of an endopeptidase. The complex slides along the docking strand with the murein synthases in front of the hydrolases, thereby acting according to the make-before-break strategy. LT, lytic transglycosylase; EP, endopeptidase; TP, transpeptidase; TP/TG,

Inside-to-outside growth of the peptidoglycan of gram-positive bacteria. The addition of newly synthesized murein layers in a relaxed state underneath the stress-bearing layers with concomitant degradation of the outermost layers is schematically illustrated. The rods represent the murein strands. For the sake of simplicity, the crosslinks between the glycans have been omitted.