Organization of peptidoglycan synthesis in nodes and separate rings at different stages of cell division of Streptococcus pneumoniae
Year: 2020
Type: article
Abstract: ABSTRACT Bacterial peptidoglycan (PG) synthesis requires strict spatial and temporal organization to reproduce specific cell shapes. In the ovoid-shaped, pathogenic bacterium Streptococcus pneumoniae ( Spn ), septal and peripheral (sidewall-like) PG synthesis occur simultaneously at midcell. To uncover the organization of proteins and activities that carry out these two modes of PG synthesis, we examined Spn cells vertically oriented onto their poles to image the division plane at the high lateral resolution of 3D-SIM (structured-illumination microscopy). Using fluorescent D-amino acid (FDAA) probes, we show that areas of new transpeptidase (TP) activity catalyzed by penicillin-binding proteins (PBPs) separate into a pair of concentric rings early in division, representing peripheral PG (pPG) synthesis (outer ring) and the leading-edge (inner ring) of septal PG (sPG) synthesis. Fluorescently tagged PBP2x or FtsZ locate primarily to the inner FDAA-marked ring, whereas PBP2b and FtsX remain in the outer ring, suggesting roles in sPG or pPG synthesis, respectively. Short pulses of FDAA labeling revealed an arrangement of separate regularly spaced “nodes” of TP activity around the division site of predivisional cells. Control experiments in wild-type and mutant strains support the interpretation of nodal spacing of TP activity, and statistical analysis confirmed that the number of nodes correlates with different ring diameters. This nodal pattern of FDAA labeling is conserved in other ovoid-shaped species. Tagged PBP2x, PBP2b, and FtsX proteins also exhibited nodal patterns with spacing comparable to that of FDAA labeling. Together, these results reveal a highly ordered PG synthesis apparatus in ovococcal bacteria at different stages of division. SIGNIFICANCE The spatial organization of PBPs and their TP activity at division septa is not well understood. In some bacteria, TP activity and PBP localization seem to be nodal (also called punctate), whereas in other bacteria, discrete foci of PBP activity are infrequently or not observed. Here we report two basic properties of the organization of PBPs and TP activity in the ovoid-shaped bacterium Spn . First, there is distinct spatial separation of the sPG machine, including FtsZ, from the pPG synthesis machine at the midcell of dividing Spn cells. Second, in predivisional cells, PBPs and TP activity are organized heterogeneously into regularly spaced nodes, whose number and dynamic distribution are likely driven by the PG synthesis of PBP:SEDS complexes.
Source: Molecular Microbiology
DOI: 10.1111/mmi.14659
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
Awards: G104085818, G1316839287, Cell surface biogenesis in Streptococcus pneumoniae, Graduate Program in Quantitative and Chemical Biology at Indiana University Bloom, Chemical Methods to Characterize Penicillin-Binding Protein Function and Interactions, Spaciotemporal Regulation of Specific Penicillin Binding Protein (PBP) Function Determined by New Activity-Based Approaches, Dynamics of bacterial peptidoglycan synthesis, Acquisition of a DeltaVision OMX-SR Imaging System, G4712865457, G5324541771, G6522974152, Investigation of the essential, conserved RodZ protein in peptidoglycan synthesis in the ovococcal pathogen, Streptococcus pneumoniae, Cortical Microtubule Patterning in the Arabidopsis Hypocotyl, Chemical Biology Studies of the Dynamics and Inhibition of Peptidoglycan Biosynthesis, G8357711161, Dynamics and Regulation of Peptidoglycan Cell Wall Synthesis in the Superbug Streptococcus pneumoniae, Discovery and characterization of new bacterial cell wall targets and inhibitors to treat resistant infections
OpenAlex ID: W3109412353