DivIVA controls the dynamics of septum splitting and cell elongation in Streptococcus pneumoniae

• Published in: mBio 2024-10, Vol.15 (10), p.e0131124
• Main Authors: Trouve, Jennyfer, Zapun, André, Bellard, Laure, Juillot, Dimitri, Pelletier, Anais, Freton, Celine, Baudoin, Morgane, Carballido-Lopez, Rut, Campo, Nathalie, Wong, Yung-Sing, Grangeasse, Christophe, Morlot, Cecile
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Cell Cycle; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Division; cell elongation; cell morphogenesis; cell wall; Cell Wall - metabolism; Cellular Biology; DivIVA; Life Sciences; Microbiology and Parasitology; Molecular and Cellular Biology; peptidoglycan; Peptidoglycan - metabolism; Research Article; Streptococcus pneumoniae - cytology; Streptococcus pneumoniae - genetics; Streptococcus pneumoniae - growth & development; Streptococcus pneumoniae - metabolism; Streptococcus pneumoniae - physiology; Subcellular Processes
• ISSN: 2150-7511; 2161-2129; 2150-7511
• DOI: 10.1128/mbio.01311-24

Bacterial shape and division rely on the dynamics of cell wall assembly, which involves regulated synthesis and cleavage of the peptidoglycan. In ovococci, these processes are coordinated within an annular mid-cell region with nanometric dimensions. More precisely, the cross-wall synthesized by the divisome is split to generate a lateral wall, whose expansion is insured by the insertion of the so-called peripheral peptidoglycan by the elongasome. Septum cleavage and peripheral peptidoglycan synthesis are, thus, crucial remodeling events for ovococcal cell division and elongation. The structural DivIVA protein has long been known as a major regulator of these processes, but its mode of action remains unknown. Here, we integrate click chemistry-based peptidoglycan labeling, direct stochastic optical reconstruction microscopy, and modeling, as well as epifluorescence and stimulated emission depletion microscopy to investigate the role of DivIVA in cell morphogenesis. Our work reveals two distinct phases of peptidoglycan remodeling during the cell cycle that are differentially controlled by DivIVA. In particular, we show that DivIVA ensures homogeneous septum cleavage and peripheral peptidoglycan synthesis around the division site and their maintenance throughout the cell cycle. Our data additionally suggest that DivIVA impacts the contribution of the elongasome and class A penicillin-binding proteins to cell elongation. We also report the position of DivIVA on either side of the septum, consistent with its known affinity for negatively curved membranes. Finally, we take the opportunity provided by these new observations to propose hypotheses for the mechanism of action of this key morphogenetic protein. MPORTANCEThis study sheds light on fundamental processes governing bacterial growth and division, using integrated click chemistry, advanced microscopy, and computational modeling approaches. It addresses cell wall synthesis mechanisms in the opportunistic human pathogen , responsible for a range of illnesses (otitis, pneumonia, meningitis, septicemia) and for one million deaths every year worldwide. This bacterium belongs to the morphological group of ovococci, which includes many streptococcal and enterococcal pathogens. In this study, we have dissected the function of DivIVA, which is a structural protein involved in cell division, morphogenesis, and chromosome partitioning in Gram-positive bacteria. This work unveils the role of DivIVA in the orchestration