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

2019 ◽  
Author(s):  
Daniel Straume ◽  
Katarzyna Wiaroslawa Piechowiak ◽  
Silje Olsen ◽  
Gro Anita Stamsås ◽  
Kari Helene Berg ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Wall Synthesis ◽  
Unique Role ◽  
Penicillin Binding Proteins ◽  
Class A ◽  
Peptidoglycan Synthesis ◽  
Resistant Form ◽  
Class B ◽  
Open Question ◽  
First Time

AbstractIn oval shapedStreptococcus pneumoniae, septal and longitudinal peptidoglycan synthesis is performed by independent functional complexes; the divisome and the elongasome. Penicillin binding proteins (PBPs) were long considered as 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. Recently, however, it was established that the monofunctional class B PBPs work together with non-PBP glycosyltransferases (FtsW and RodA) to make up the core peptidoglycan synthesizing machineries within the pneumococcal divisome (FtsW/PBP2x) and elongasome (RodA/PBP2b). The function of class A PBPs is therefore now an open question. Here we utilize the peptidoglycan hydrolase CbpD to show that class A PBPs have an autonomous role during cell wall synthesis inS. pneumoniae. Purified CbpD was shown to target the septum ofS. pneumoniaecells. Using assays to specifically inhibit PBP2x, we demonstrate that CbpD specifically target nascent peptidoglycan synthesized by the divisome. Notably, class A PBPs could process this nascent peptidoglycan from a CbpD-sensitive to a CbpD-resistant form. The class A PBP mediated processing was independent of divisome and elongasome activities. Class A PBPs thus constitute an autonomous functional entity which processes or repairs nascent peptidoglycan synthesized by FtsW/PBP2x. Our results support a model in which pneumococcal peptidoglycan is made by three functional entities, the divisome, the elongasome and a peptidoglycan-repairing or -remodelling complex consisting of bifunctional PBPs. To our knowledge this is the first time a specific function has been identified for class A PBPs in bacterial cell wall synthesis.

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

2020 ◽  
Vol 117 (11) ◽  
pp. 6129-6138 ◽  
Author(s):  
Daniel Straume ◽  
Katarzyna Wiaroslawa Piechowiak ◽  
Silje Olsen ◽  
Gro Anita Stamsås ◽  
Kari Helene Berg ◽  
...  
Keyword(s):  
Cell Wall ◽  
Peptidoglycan Hydrolase ◽  
Unique Role ◽  
Penicillin Binding Proteins ◽  
The Core ◽  
Class A ◽  
Peptidoglycan Synthesis ◽  
Resistant Form ◽  
Class B ◽  
Open Question

In oval-shapedStreptococcus pneumoniae, 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. Recently, however, it was established that the monofunctional class B PBPs work together with transmembrane glycosyltransferases (FtsW and RodA) from the shape, elongation, division, and sporulation (SEDS) family to make up the core peptidoglycan-synthesizing machineries within the pneumococcal divisome (FtsW/PBP2x) and elongasome (RodA/PBP2b). The function of class A PBPs is therefore now an open question. Here we utilize the peptidoglycan hydrolase CbpD that targets the septum ofS. pneumoniaecells to show that class A PBPs have an autonomous role during pneumococcal cell wall synthesis. Using assays to specifically inhibit the function of PBP2x and FtsW, we demonstrate that CbpD attacks nascent peptidoglycan synthesized by the divisome. Notably, class A PBPs could process this nascent peptidoglycan from a CbpD-sensitive to a CbpD-resistant form. The class A PBP-mediated processing was independent of divisome and elongasome activities. Class A PBPs thus constitute an autonomous functional entity which processes recently formed peptidoglycan synthesized by FtsW/PBP2×. Our results support a model in which mature pneumococcal peptidoglycan is synthesized by three functional entities, the divisome, the elongasome, and bifunctional PBPs. The latter modify existing peptidoglycan but are probably not involved in primary peptidoglycan synthesis.

scholarly journals Unipolar peptidoglycan synthesis in the Rhizobiales requires an essential class A penicillin-binding protein

2021 ◽  
Author(s):  
Michelle A Williams ◽  
Alena Aliashkevich ◽  
Elizaveta Krol ◽  
Erkin Kuru ◽  
Jacob M Bouchier ◽  
...  
Keyword(s):  
Cell Wall ◽  
Binding Protein ◽  
Compositional Analysis ◽  
Growth Patterns ◽  
Penicillin Binding Protein ◽  
Cell Wall Synthesis ◽  
Alternative Mode ◽  
Single Class ◽  
Class A ◽  
Peptidoglycan Synthesis

Members of the Rhizobiales are polarly-growing bacteria that lack homologs of the canonical rod complex. To investigate the mechanisms underlying polar cell wall synthesis, we systematically probed the function of cell wall synthesis enzymes in the plant-pathogen Agrobacterium tumefaciens. The development of fluorescent D-amino acid dipeptide (FDAAD) probes, which are incorporated into peptidoglycan by penicillin-binding proteins in A. tumefaciens, enabled us to monitor changes in growth patterns in the mutants. Use of these fluorescent cell wall probes and peptidoglycan compositional analysis convincingly demonstrate that a single class A penicillin-binding protein is essential for polar peptidoglycan synthesis. Furthermore, we find evidence of an alternative mode of cell wall synthesis that likely requires LD-transpeptidase activity. Genetic analysis and cell wall targeting antibiotics reveal that the mechanism of unipolar growth is conserved in Sinorhizobium and Brucella. This work provides insights into unipolar peptidoglycan biosynthesis employed by the Rhizobiales during cell elongation.

scholarly journals Insights into the role of lipoteichoic acids in Bacillus subtilis- a new function for MprF

2021 ◽  
Author(s):  
Aurelie Guyet ◽  
Amirah Alofi ◽  
Richard A Daniel
Keyword(s):  
Bacillus Subtilis ◽  
Cell Envelope ◽  
Cellular Level ◽  
Penicillin Binding Proteins ◽  
Class A ◽  
Peptidoglycan Synthesis ◽  
A Cell ◽  
Antimicrobial Peptide Resistance ◽  
Lipoteichoic Acids

In Bacillus subtilis, the cell is protected from the environment by a cell envelope, which comprises of layers of peptidoglycan that maintain the cell shape and anionic teichoic acids polymers whose biological function remains unclear. In B. subtilis, loss of all Class A Penicillin-Binding Proteins (aPBPs) which function in peptidoglycan synthesis is conditionally lethal. Here we show that this lethality is associated with an alteration of the lipoteichoic acids (LTA) and the accumulation of the major autolysin LytE in the cell wall. We provide the first evidence that the length and abundance of LTA acts to regulate the cellular level of LytE. Importantly, we identify a novel function for the aminoacyl-phosphatidylglycerol synthase MprF which acts to modulate LTA biosynthesis in B. subtilis and in the pathogen Staphylococcus aureus. This finding has implications for our understanding of antimicrobial peptide resistance (particularly daptomycin) in clinically relevant bacteria and MprF-associated virulence in pathogens, such as methicillin resistant S. aureus.

scholarly journals Real time monitoring of peptidoglycan synthesis by membrane-reconstituted penicillin binding proteins

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Victor M Hernández-Rocamora ◽  
Natalia Baranova ◽  
Katharina Peters ◽  
Eefjan Breukink ◽  
Martin Loose ◽  
...  
Keyword(s):  
Real Time ◽  
Lipid Bilayers ◽  
High Throughput Screening ◽  
Binding Proteins ◽  
Cell Envelope ◽  
Penicillin Binding Proteins ◽  
Peptidoglycan Biosynthesis ◽  
Class A ◽  
Peptidoglycan Synthesis ◽  
Osmotic Lysis

Peptidoglycan is an essential component of the bacterial cell envelope that surrounds the cytoplasmic membrane to protect the cell from osmotic lysis. Important antibiotics such as β-lactams and glycopeptides target peptidoglycan biosynthesis. Class A penicillin binding proteins are bifunctional membrane-bound peptidoglycan synthases that polymerize glycan chains and connect adjacent stem peptides by transpeptidation. How these enzymes work in their physiological membrane environment is poorly understood. Here we developed a novel FRET-based assay to follow in real time both reactions of class A PBPs reconstituted in liposomes or supported lipid bilayers and we applied this assay with PBP1B homologues from Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii in the presence or absence of their cognate lipoprotein activator. Our assay will allow unravelling the mechanisms of peptidoglycan synthesis in a lipid-bilayer environment and can be further developed to be used for high throughput screening for new antimicrobials.

scholarly journals Interactions between Penicillin-Binding Proteins (PBPs) and Two Novel Classes of PBP Inhibitors, Arylalkylidene Rhodanines and Arylalkylidene Iminothiazolidin-4-ones

2004 ◽  
Vol 48 (3) ◽  
pp. 961-969 ◽  
Author(s):  
Astrid Zervosen ◽  
Wei-Ping Lu ◽  
Zhouliang Chen ◽  
Ronald E. White ◽  
Thomas P. Demuth ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Cell Wall Synthesis ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Peptidoglycan Biosynthesis ◽  
Vancomycin Resistant ◽  
Inhibitory Activities

ABSTRACT Several non-β-lactam compounds were active against various gram-positive and gram-negative bacterial strains. The MICs of arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-ones were lower than those of ampicillin and cefotaxime for methicillin-resistant Staphylococcus aureus MI339 and vancomycin-resistant Enterococcus faecium EF12. Several compounds were found to inhibit the cell wall synthesis of S. aureus and the last two steps of peptidoglycan biosynthesis catalyzed by ether-treated cells of Escherichia coli or cell wall membrane preparations of Bacillus megaterium. The effects of the arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-one derivatives on E. coli PBP 3 and PBP 5, Streptococcus pneumoniae PBP 2xS (PBP 2x from a penicillin-sensitive strain) and PBP 2xR (PBP 2x from a penicillin-resistant strain), low-affinity PBP 2a of S. aureus, and the Actinomadura sp. strain R39 and Streptomyces sp. strain R61 dd-peptidases were studied. Some of the compounds exhibited inhibitory activities in the 10 to 100 μM concentration range. The inhibition of PBP 2xS by several of them appeared to be noncompetitive. The dissociation constant for the best inhibitor (Ki = 10 μM) was not influenced by the presence of the substrate.

scholarly journals Author response: Class-A penicillin binding proteins do not contribute to cell shape but repair cell-wall defects

2020 ◽  
Author(s):  
Antoine Vigouroux ◽  
Baptiste Cordier ◽  
Andrey Aristov ◽  
Laura Alvarez ◽  
Gizem Özbaykal ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Binding Proteins ◽  
Author Response ◽  
Response Class ◽  
Penicillin Binding Proteins ◽  
Class A

scholarly journals Class A Penicillin-Binding Protein-mediated cell wall synthesis promotes structural integrity during peptidoglycan endopeptidase insufficiency

2020 ◽  
Author(s):  
Shannon G. Murphy ◽  
Andrew N. Murtha ◽  
Ziyi Zhao ◽  
Laura Alvarez ◽  
Peter Diebold ◽  
...  
Keyword(s):  
Cell Wall ◽  
Vibrio Cholerae ◽  
Bacterial Cell ◽  
Structural Integrity ◽  
Cell Mass ◽  
Bacterial Cell Wall ◽  
Wall Material ◽  
Cell Wall Synthesis ◽  
Class A ◽  
Rod System

AbstractThe bacterial cell wall is composed primarily of peptidoglycan (PG), a poly-aminosugar that is essential to sustain cell shape, growth and structural integrity. PG is synthesized by two different types of synthase complexes (class A Penicillin-binding Proteins [PBP]s/Lpos and Shape, Elongation, Division, Sporulation [SEDS]/class B PBP pairs) and degraded by ‘autolytic’ enzymes to accommodate growth processes. It is thought that autolsyin activity (and particulary the activity of endopeptidases, EPs) is required for PG synthesis and incorporation by creating gaps that are patched and paved by PG synthases, but the exact relationship between autolysins and the separate synthesis machineries remains incompletely understood. Here, we have probed the consequences of EP depletion for PG synthesis in the diarrheal pathogen Vibrio cholerae. We found that EP depletion resulted in severe morphological defects, increased cell mass, a decline in viability, and continuing (yet aberrant) incorporation of cell wall material. Mass increase and cell wall incorporation proceeded in the presence of Rod system inhibitors, but was abolished upon inhibition of aPBPs. However, the Rod system remained functional (i.e., exhibited sustained directed motion) even after prolonged EP depletion, without effectively promoting cell elongation. Lastly, heterologous expression of an EP from Neisseria gonorrhoeae could fully complement growth and morphology of an EP-insufficient V. cholerae. Overall, our findings suggest that in V. cholerae, the Rod system requires endopeptidase activity (but not necessarily direct interaction with EPs) to promote cell expansion and substantial PG incorporation, whereas aPBPs are able to engage in sacculus construction even during severe EP insufficiency.ImportanceSynthesis and turnover of the bacterial cell wall must be tightly co-ordinated to avoid structural integrity failure and cell death. Details of this coordination are poorly understood, particularly if and how cell wall turnover enzymes are required for the activity of the different cell wall synthesis machines. Our results suggest that in Vibrio cholerae, one class of turnover enzymes, the endopeptidases, are required only for substantial PG incorporation mediated by the Rod system, while the aPBPs maintain structural integrity during endopeptidase insufficiency. Our results suggest that aPBPs are more versatile than the Rod system in their ability to recognize cell wall gaps formed by autolysins other than the major endopeptidases, adding to our understanding of the co-ordination between autolysins and cell wall synthases. A detailed understanding of autolysin biology may promote the development of antibiotics that target these essential turnover processes.

scholarly journals Multimodular Penicillin-Binding Proteins: An Enigmatic Family of Orthologs and Paralogs

1998 ◽  
Vol 62 (4) ◽  
pp. 1079-1093 ◽  
Author(s):  
Colette Goffin ◽  
Jean-Marie Ghuysen
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Full Size ◽  
Penicillin Binding Proteins ◽  
Gram Positive Bacteria ◽  
Class A ◽  
Class B ◽  
Resistance To Penicillin

SUMMARY The monofunctional penicillin-binding dd-peptidases and penicillin-hydrolyzing serine β-lactamases diverged from a common ancestor by the acquisition of structural changes in the polypeptide chain while retaining the same folding, three-motif amino acid sequence signature, serine-assisted catalytic mechanism, and active-site topology. Fusion events gave rise to multimodular penicillin-binding proteins (PBPs). The acyl serine transferase penicillin-binding (PB) module possesses the three active-site defining motifs of the superfamily; it is linked to the carboxy end of a non-penicillin-binding (n-PB) module through a conserved fusion site; the two modules form a single polypeptide chain which folds on the exterior of the plasma membrane and is anchored by a transmembrane spanner; and the full-size PBPs cluster into two classes, A and B. In the class A PBPs, the n-PB modules are a continuum of diverging sequences; they possess a five-motif amino acid sequence signature, and conserved dicarboxylic amino acid residues are probably elements of the glycosyl transferase catalytic center. The PB modules fall into five subclasses: A1 and A2 in gram-negative bacteria and A3, A4, and A5 in gram-positive bacteria. The full-size class A PBPs combine the required enzymatic activities for peptidoglycan assembly from lipid-transported disaccharide-peptide units and almost certainly prescribe different, PB-module specific traits in peptidoglycan cross-linking. In the class B PBPs, the PB and n-PB modules cluster in a concerted manner. A PB module of subclass B2 or B3 is linked to an n-PB module of subclass B2 or B3 in gram-negative bacteria, and a PB module of subclass B1, B4, or B5 is linked to an n-PB module of subclass B1, B4, or B5 in gram-positive bacteria. Class B PBPs are involved in cell morphogenesis. The three motifs borne by the n-PB modules are probably sites for module-module interaction and the polypeptide stretches which extend between motifs 1 and 2 are sites for protein-protein interaction. The full-size class B PBPs are an assortment of orthologs and paralogs, which prescribe traits as complex as wall expansion and septum formation. PBPs of subclass B1 are unique to gram-positive bacteria. They are not essential, but they represent an important mechanism of resistance to penicillin among the enterococci and staphylococci. Natural evolution and PBP- and β-lactamase-mediated resistance show that the ability of the catalytic centers to adapt their properties to new situations is limitless. Studies of the reaction pathways by using the methods of quantum chemistry suggest that resistance to penicillin is a road of no return.

scholarly journals DivIVA Is Required for Polar Growth in the MreB-Lacking Rod-Shaped Actinomycete Corynebacterium glutamicum

2008 ◽  
Vol 190 (9) ◽  
pp. 3283-3292 ◽  
Author(s):  
Michal Letek ◽  
Efrén Ordóñez ◽  
José Vaquera ◽  
William Margolin ◽  
Klas Flärdh ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Streptococcus Pneumoniae ◽  
Corynebacterium Glutamicum ◽  
Chromosome Segregation ◽  
Polar Growth ◽  
Cell Wall Synthesis ◽  
Peptidoglycan Synthesis ◽  
Polarized Cell Growth

ABSTRACT The actinomycete Corynebacterium glutamicum grows as rod-shaped cells by zonal peptidoglycan synthesis at the cell poles. In this bacterium, experimental depletion of the polar DivIVA protein (DivIVACg) resulted in the inhibition of polar growth; consequently, these cells exhibited a coccoid morphology. This result demonstrated that DivIVA is required for cell elongation and the acquisition of a rod shape. DivIVA from Streptomyces or Mycobacterium localized to the cell poles of DivIVACg-depleted C. glutamicum and restored polar peptidoglycan synthesis, in contrast to DivIVA proteins from Bacillus subtilis or Streptococcus pneumoniae, which localized at the septum of C. glutamicum. This confirmed that DivIVAs from actinomycetes are involved in polarized cell growth. DivIVACg localized at the septum after cell wall synthesis had started and the nucleoids had already segregated, suggesting that in C. glutamicum DivIVA is not involved in cell division or chromosome segregation.

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