Class A PBPs have a distinct and unique role in the construction of the pneumococcal cell wall.

In oval-shaped , septal and longitudinal peptidoglycan syntheses are performed by independent functional complexes: the divisome and the elongasome. Penicillin-binding proteins (PBPs) were long considered the key peptidoglycan-synthesizing enzymes in these complexes. Among these were the bifunctional class A PBPs, which are both glycosyltransferases and transpeptidases, and monofunctional class B PBPs with only transpeptidase activity.

Identification of pneumococcal proteins that are functionally linked to penicillin-binding protein 2b (PBP2b).

The oval shape of pneumococci results from a combination of septal and lateral peptidoglycan synthesis. The septal cross-wall is synthesized by the divisome, while the elongasome drives cell elongation by inserting new peptidoglycan into the lateral cell wall. Each of these molecular machines contains penicillin-binding proteins (PBPs), which catalyze the final stages of peptidoglycan synthesis, plus a number of accessory proteins.

The function of the transmembrane and cytoplasmic domains of pneumococcal penicillin-binding proteins 2x and 2b extends beyond that of simple anchoring devices.

The biosynthesis of cell-wall peptidoglycan is a complex process that involves six different penicillin-binding proteins (PBPs) in Streptococcus pneumoniae. Two of these, PBP2x and PBP2b, are monofunctional transpeptidases that catalyse the formation of peptide cross-links between adjacent glycan strands. Both of them are bitopic membrane proteins with a small cytoplasmic and a large extracellular domain.

Effects of low PBP2b levels on cell morphology and peptidoglycan composition in Streptococcus pneumoniae R6.

Streptococcus pneumoniae produces two class B penicillin-binding proteins, PBP2x and PBP2b, both of which are essential. It is generally assumed that PBP2x is specifically involved in septum formation, while PBP2b is dedicated to peripheral cell wall synthesis. However, little experimental evidence exists to substantiate this belief.

Properties and biological role of streptococcal fratricins.

Competence for natural genetic transformation is widespread in the genus Streptococcus. The current view is that all streptococcal species possess this property. In addition to the proteins required for DNA uptake and recombination, competent streptococci secrete muralytic enzymes termed fratricins.

LytF, a novel competence-regulated murein hydrolase in the genus Streptococcus.

Streptococcus pneumoniae and probably most other members of the genus Streptococcus are competent for natural genetic transformation. During the competent state, S. pneumoniae produces a murein hydrolase, CbpD, that kills and lyses noncompetent pneumococci and closely related species.

Peptide-regulated gene depletion system developed for use in Streptococcus pneumoniae.

To facilitate the study of pneumococcal genes that are essential for viability or normal cell growth, we sought to develop a tightly regulated, titratable gene depletion system that interferes minimally with normal cellular functions. A possible candidate for such a system is the recently discovered signal transduction pathway regulating competence for natural transformation in Streptococcus thermophilus. This pathway, which is unrelated to the ComCDE pathway used for competence regulation in Streptococcus pneumoniae, has not been fully elucidated, but it is known to include a short unmodified signaling peptide, ComS*, an oligopeptide transport system, Ami, and a transcriptional activator, ComR.

Pneumococcal CbpD is a murein hydrolase that requires a dual cell envelope binding specificity to kill target cells during fratricide.

Pneumococci that are competent for natural genetic transformation express a number of proteins involved in binding, uptake, translocation and recombination of DNA. In addition, they attack and lyse non-competent sister cells present in the same environment. This phenomenon has been termed fratricide.