Abstract
The peptide network of Streptococcus pneumoniae cell walls was solubilized using the pneumococcal autolytic amidase (N-acetylmuramoyl-L-alanine amidase, EC 3.5.1.28). The peptide material was fractionated into size classes by gel filtration followed by reverse-phase high-performance liquid chromatography which resolved the peptide population into over 40 fractions. About 40% of the lysines present participate in cross-links between stem peptides. The main components (3 monomers, 5 dimers, and 2 trimers), accounting for 77% of all the wall peptides, were purified. Their structures were determined using a combination of amino acid and end-group analysis, mass spectrometry, and gas-phase sequencing. Two different types of cross-links between stem peptides were found. In the most abundant type there is an alanylserine cross-bridge between the alanine in position 4 of the donor stem peptide and the lysine at position 3 of the acceptor peptide, as in type A3 peptidoglycan. In the second type of cross-link there is no intervening cross-bridge, as in the type A1 peptidoglycan of Gram-negative bacteria. The data indicate that pneumococcal peptidoglycan has a structural complexity comparable to that recently shown in some Gram-negative species.
Original language | English |
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Pages (from-to) | 15400-15405 |
Number of pages | 6 |
Journal | Journal of Biological Chemistry |
Volume | 262 |
Issue number | 32 |
Publication status | Published - 15 Nov 1987 |
Externally published | Yes |