scholarly journals Mutations in Peptidoglycan Synthesis GeneponAImprove Electrotransformation Efficiency ofCorynebacterium glutamicumATCC 13869

2018 ◽  
Vol 84 (24) ◽  
Author(s):  
Jiao Liu ◽  
Yu Wang ◽  
Yujiao Lu ◽  
Xiaomeng Ni ◽  
Xuan Guo ◽  
...  

ABSTRACTCorynebacterium glutamicumis frequently engineered to serve as a versatile platform and model microorganism. However, due to its complex cell wall structure, transformation ofC. glutamicumwith exogenous DNA is inefficient. Although efforts have been devoted to improve the transformation efficiency by using cell wall-weakening agents, direct genetic engineering of cell wall synthesis for enhancing cell competency has not been explored thus far. Herein, we reported that engineering of peptidoglycan synthesis could significantly increase the transformation efficiency ofC. glutamicum. Comparative analysis ofC. glutamicumwild-type strain ATCC 13869 and a mutant with high electrotransformation efficiency revealed nine mutations in eight cell wall synthesis-related genes. Among them, the Y489C mutation in bifunctional peptidoglycan glycosyltransferase/peptidoglycandd-transpeptidase PonA dramatically increased the electrotransformation of strain ATCC 13869 by 19.25-fold in the absence of cell wall-weakening agents, with no inhibition on growth. The Y489C mutation had no effect on the membrane localization of PonA but affected the peptidoglycan structure. Deletion of theponAgene led to more dramatic changes to the peptidoglycan structure but only increased the electrotransformation by 4.89-fold, suggesting that appropriate inhibition of cell wall synthesis benefited electrotransformation more. Finally, we demonstrated that the PonAY489Cmutation did not cause constitutive or enhanced glutamate excretion, making its permanent existence inC. glutamicumATCC 13869 acceptable. This study demonstrates that genetic engineering of genes involved in cell wall synthesis, especially peptidoglycan synthesis, is a promising strategy to improve the electrotransformation efficiency ofC. glutamicum.IMPORTANCEMetabolic engineering and synthetic biology are now the key enabling technologies for manipulating microorganisms to suit the practical outcomes desired by humankind. The introduction of exogenous DNA into cells is an indispensable step for this purpose. However, some microorganisms, including the important industrial workhorseCorynebacterium glutamicum, possess a complex cell wall structure to shield cells against exogenous DNA. Although genes responsible for cell wall synthesis inC. glutamicumare known, engineering of related genes to improve cell competency has not been explored yet. In this study, we demonstrate that mutations in cell wall synthesis genes can significantly improve the electrotransformation efficiency ofC. glutamicum. Notably, the Y489C mutation in bifunctional peptidoglycan glycosyltransferase/peptidoglycandd-transpeptidase PonA increased electrotransformation efficiency by 19.25-fold by affecting peptidoglycan synthesis.

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Luis Alberto Vega ◽  
Gary C. Port ◽  
Michael G. Caparon

ABSTRACTThe ExPortal ofStreptococcus pyogenesis a focal microdomain of the cytoplasmic membrane that clusters the translocons of the general secretory pathway with accessory factors to facilitate the maturation of secreted polypeptides. While it is known that the ExPortal is enriched in anionic lipids, the mechanisms that organize the ExPortal are poorly understood. In the present study, we examined the role of the cell wall in organizing and maintaining the ExPortal. Removal of the cell wall resulted in a loss of ExPortal focal integrity accompanied by the circumferential redistribution of ExPortal lipid and protein components. A similar loss occurred upon treatment with gallidermin, a nonpermeabilizing lantibiotic that targets the lipid II precursor of peptidoglycan synthesis, and this treatment disrupted the secretion of several ExPortal substrates. Furthermore, several enzymes involved in the membrane-associated steps of lipid II synthesis, including MraY and MurN, were found to localize to a single discrete focus in the membrane that was coincident with the focal location of the secretory translocons and the anionic lipid microdomain. These data suggest that the ExPortal is associated with the site of peptidoglycan precursor synthesis and that peptidoglycan biogenesis influences ExPortal organization. These data add to an emerging literature indicating that cell wall biogenesis, cell division, and protein secretion are spatially coorganized processes.IMPORTANCESince Gram-positive bacteria lack a periplasmic space, they lack a protected compartment to spatially coordinate interaction between newly secreted proteins and the factors required to process them. This represents a significant problem for pathogens that depend on the secretion of toxins and cell wall-associated adhesins to cause disease. Streptococci solve this dilemma by restricting secretion and processing factors to a defined region of the membrane. However, the mechanisms that promote restriction are not understood. In this study, we show that restriction of these factors in the pathogenStreptococcus pyogenesis intimately linked with the presence of the cell wall and its synthesis. Furthermore, several cell wall synthesis proteins are also restricted to the site of protein secretion. This study contributes to our understanding of how the Gram-positive cell is organized to coordinate protein secretion and biogenesis with cell wall synthesis and to the ongoing development of antibiotics that target these processes.


2014 ◽  
Vol 82 (10) ◽  
pp. 4104-4117 ◽  
Author(s):  
Mushtaq Mir ◽  
Sladjana Prisic ◽  
Choong-Min Kang ◽  
Shichun Lun ◽  
Haidan Guo ◽  
...  

ABSTRACTTo persist and cause disease in the host,Mycobacterium tuberculosismust adapt to its environment during infection. Adaptations include changes in nutrient utilization and alterations in growth rate.M. tuberculosisRv1422 is a conserved gene of unknown function that was found in a genetic screen to interact with themce4cholesterol uptake locus. The Rv1422 protein is phosphorylated by theM. tuberculosisSer/Thr kinases PknA and PknB, which regulate cell growth and cell wall synthesis.Bacillus subtilisstrains lacking the Rv1422 homologueyvcKgrow poorly on several carbon sources, andyvcKis required for proper localization of peptidoglycan synthesis. Here we show thatMycobacterium smegmatisandM. tuberculosisstrains lacking Rv1422 have growth defects in minimal medium containing limiting amounts of several different carbon sources. These strains also have morphological abnormalities, including shortened and bulging cells, suggesting a cell wall defect. In both mycobacterial species, the Rv1422 protein localizes uniquely to the growing cell pole, the site of peptidoglycan synthesis in mycobacteria. AnM. tuberculosisΔRv1422 strain is markedly attenuated for virulence in a mouse infection model, where it elicits decreased inflammation in the lungs and shows impaired bacterial persistence. These findings led us to name this genecuvA(carbonutilization andvirulence proteinA) and to suggest a model in which deletion ofcuvAleads to changes in nutrient uptake and/or metabolism that affect cell wall structure, morphology, and virulence. Its role in virulence suggests that CuvA may be a useful target for novel inhibitors ofM. tuberculosisduring infection.


2010 ◽  
Vol 10 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Hong X. Wang ◽  
Lois M. Douglas ◽  
Vishukumar Aimanianda ◽  
Jean-Paul Latgé ◽  
James B. Konopka

ABSTRACTTheCandida albicansplasma membrane plays important roles in interfacing with the environment, morphogenesis, and cell wall synthesis. The role of the Sur7 protein in cell wall structure and function was analyzed, since previous studies showed that this plasma membrane protein is needed to prevent abnormal intracellular growth of the cell wall. Sur7 localizes to stable patches in the plasma membrane, known as MCC (membrane compartment occupied by Can1), that are associated with eisosome proteins. Thesur7Δ mutant cells displayed increased sensitivity to factors that exacerbate cell wall defects, such as detergent (SDS) and the chitin-binding agents calcofluor white and Congo red. Thesur7Δ cells were also slightly more sensitive to inhibitors that block the synthesis of cell wall chitin (nikkomycin Z) and β-1,3-glucan (caspofungin). In contrast, Fmp45, a paralog of Sur7 that also localizes to punctate plasma membrane patches, did not have a detectable role in cell wall synthesis. Chemical analysis of cell wall composition demonstrated thatsur7Δ cells contain decreased levels of β-glucan, a glucose polymer that confers rigidity on the cell wall. Consistent with this,sur7Δ cells were more sensitive to lysis, which could be partially rescued by increasing the osmolarity of the medium. Interestingly, Sur7 is present in static patches, whereas β-1,3-glucan synthase is mobile in the plasma membrane and is often associated with actin patches. Thus, Sur7 may influence β-glucan synthesis indirectly, perhaps by altering the functions of the cell signaling components that localize to the MCC and eisosome domains.


mBio ◽  
2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Peter Mellroth ◽  
Tatyana Sandalova ◽  
Alexey Kikhney ◽  
Francisco Vilaplana ◽  
Dusan Hesek ◽  
...  

ABSTRACT The cytosolic N-acetylmuramoyl-l-alanine amidase LytA protein of Streptococcus pneumoniae, which is released by bacterial lysis, associates with the cell wall via its choline-binding motif. During exponential growth, LytA accesses its peptidoglycan substrate to cause lysis only when nascent peptidoglycan synthesis is stalled by nutrient starvation or β-lactam antibiotics. Here we present three-dimensional structures of LytA and establish the requirements for substrate binding and catalytic activity. The solution structure of the full-length LytA dimer reveals a peculiar fold, with the choline-binding domains forming a rigid V-shaped scaffold and the relatively more flexible amidase domains attached in a trans position. The 1.05-Å crystal structure of the amidase domain reveals a prominent Y-shaped binding crevice composed of three contiguous subregions, with a zinc-containing active site localized at the bottom of the branch point. Site-directed mutagenesis was employed to identify catalytic residues and to investigate the relative impact of potential substrate-interacting residues lining the binding crevice for the lytic activity of LytA. In vitro activity assays using defined muropeptide substrates reveal that LytA utilizes a large substrate recognition interface and requires large muropeptide substrates with several connected saccharides that interact with all subregions of the binding crevice for catalysis. We hypothesize that the substrate requirements restrict LytA to the sites on the cell wall where nascent peptidoglycan synthesis occurs. IMPORTANCE Streptococcus pneumoniae is a human respiratory tract pathogen responsible for millions of deaths annually. Its major pneumococcal autolysin, LytA, is required for autolysis and fratricidal lysis and functions as a virulence factor that facilitates the spread of toxins and factors involved in immune evasion. LytA is also activated by penicillin and vancomycin and is responsible for the lysis induced by these antibiotics. The factors that regulate the lytic activity of LytA are unclear, but it was recently demonstrated that control is at the level of substrate recognition and that LytA required access to the nascent peptidoglycan. The present study was undertaken to structurally and functionally investigate LytA and its substrate-interacting interface and to determine the requirements for substrate recognition and catalysis. Our results reveal that the amidase domain comprises a complex substrate-binding crevice and needs to interact with a large-motif epitope of peptidoglycan for catalysis.


2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Wen Yu ◽  
Kelsey M. Hallinen ◽  
Kevin B. Wood

ABSTRACTSubinhibitory concentrations of antibiotics have been shown to enhance biofilm formation in multiple bacterial species. While antibiotic exposure has been associated with modulated expression of many biofilm-related genes, the mechanisms of drug-induced biofilm formation remain a focus of ongoing research efforts and may vary significantly across species. In this work, we investigate antibiotic-induced biofilm formation inEnterococcus faecalis, a leading cause of nosocomial infections. We show that biofilm formation is enhanced by subinhibitory concentrations of cell wall synthesis inhibitors but not by inhibitors of protein, DNA, folic acid, or RNA synthesis. Furthermore, enhanced biofilm is associated with increased cell lysis, increases in extracellular DNA (eDNA) levels, and increases in the density of living cells in the biofilm. In addition, we observe similar enhancement of biofilm formation when cells are treated with nonantibiotic surfactants that induce cell lysis. These findings suggest that antibiotic-induced biofilm formation is governed by a trade-off between drug toxicity and the beneficial effects of cell lysis. To understand this trade-off, we developed a simple mathematical model that predicts changes in antibiotic-induced biofilm formation due to external perturbations, and we verified these predictions experimentally. Specifically, we demonstrate that perturbations that reduce eDNA (DNase treatment) or decrease the number of living cells in the planktonic phase (a second antibiotic) decrease biofilm induction, while chemical inhibitors of cell lysis increase relative biofilm induction and shift the peak to higher antibiotic concentrations. Overall, our results offer experimental evidence linking cell wall synthesis inhibitors, cell lysis, increased eDNA levels, and biofilm formation inE. faecaliswhile also providing a predictive quantitative model that sheds light on the interplay between cell lysis and antibiotic efficacy in developing biofilms.


2020 ◽  
Vol 203 (2) ◽  
pp. e00463-20
Author(s):  
Amit Bhambhani ◽  
Isabella Iadicicco ◽  
Jules Lee ◽  
Syed Ahmed ◽  
Max Belfatto ◽  
...  

ABSTRACTPrevious work identified gene product 56 (gp56), encoded by the lytic bacteriophage SP01, as being responsible for inhibition of Bacillus subtilis cell division during its infection. Assembly of the essential tubulin-like protein FtsZ into a ring-shaped structure at the nascent site of cytokinesis determines the timing and position of division in most bacteria. This FtsZ ring serves as a scaffold for recruitment of other proteins into a mature division-competent structure permitting membrane constriction and septal cell wall synthesis. Here, we show that expression of the predicted 9.3-kDa gp56 of SP01 inhibits later stages of B. subtilis cell division without altering FtsZ ring assembly. Green fluorescent protein-tagged gp56 localizes to the membrane at the site of division. While its localization does not interfere with recruitment of early division proteins, gp56 interferes with the recruitment of late division proteins, including Pbp2b and FtsW. Imaging of cells with specific division components deleted or depleted and two-hybrid analyses suggest that gp56 localization and activity depend on its interaction with FtsL. Together, these data support a model in which gp56 interacts with a central part of the division machinery to disrupt late recruitment of the division proteins involved in septal cell wall synthesis.IMPORTANCE Studies over the past decades have identified bacteriophage-encoded factors that interfere with host cell shape or cytokinesis during viral infection. The phage factors causing cell filamentation that have been investigated to date all act by targeting FtsZ, the conserved prokaryotic tubulin homolog that composes the cytokinetic ring in most bacteria and some groups of archaea. However, the mechanisms of several phage factors that inhibit cytokinesis, including gp56 of bacteriophage SP01 of Bacillus subtilis, remain unexplored. Here, we show that, unlike other published examples of phage inhibition of cytokinesis, gp56 blocks B. subtilis cell division without targeting FtsZ. Rather, it utilizes the assembled FtsZ cytokinetic ring to localize to the division machinery and to block recruitment of proteins needed for septal cell wall synthesis.


2014 ◽  
Vol 58 (3) ◽  
pp. 1749-1756 ◽  
Author(s):  
Jean-Emmanuel Hugonnet ◽  
Nabila Haddache ◽  
Carole Veckerlé ◽  
Lionel Dubost ◽  
Arul Marie ◽  
...  

ABSTRACTSynthesis of peptidoglycan precursors ending ind-lactate (d-Lac) is thought to be responsible for glycopeptide resistance in members of the orderActinomycetalesthat produce these drugs and in related soil bacteria. More recently, the peptidoglycan of several members of the orderActinomycetaleswas shown to be cross-linked byl,d-transpeptidases that use tetrapeptide acyl donors devoid of the target of glycopeptides. To evaluate the contribution of these resistance mechanisms, we have determined the peptidoglycan structure ofStreptomyces coelicolorA(3)2, which harbors avanHAXgene cluster for the production of precursors ending ind-Lac, andNonomuraeasp. strain ATCC 39727, which is devoid ofvanHAXand produces the glycopeptide A40296. Vancomycin retained residual activity againstS. coelicolorA(3)2 despite efficient incorporation ofd-Lac into cytoplasmic precursors. This was due to ad,d-transpeptidase-catalyzed reaction that generated a stem pentapeptide recognized by glycopeptides by the exchange ofd-Lac ford-Ala and Gly. The contribution ofl,d-transpeptidases to resistance was limited by the supply of tetrapeptide acyl donors, which are essential for the formation of peptidoglycan cross-links by these enzymes. In the absence of a cytoplasmic metallo-d,d-carboxypeptidase, the tetrapeptide substrate was generated by hydrolysis of the C-terminald-Lac residue of the stem pentadepsipeptide in the periplasm in competition with the exchange reaction catalyzed byd,d-transpeptidases. InNonomuraeasp. strain ATCC 39727, the contribution ofl,d-transpeptidases to glycopeptide resistance was limited by the incomplete conversion of pentapeptides into tetrapeptides despite the production of a cytoplasmic metallo-d,d-carboxypeptidase. Since the level of drug production exceeds the level of resistance, we propose thatl,d-transpeptidases merely act as a tolerance mechanism in this bacterium.


2012 ◽  
Vol 57 (1) ◽  
pp. 626-628 ◽  
Author(s):  
Susanne Perkhofer ◽  
Barbara Striessnig ◽  
Bettina Sartori ◽  
Barbara Hausott ◽  
Helmut W. Ott ◽  
...  

ABSTRACTThe combination of platelets and anidulafungin at 0.03 μg/ml significantly (P< 0.05) reduced the germination rate and hyphal elongation inAspergillus fumigatuscompared to those with either anidulafungin only or an untreated control. Platelets decreased the expression of thefksgene, which plays an important role in cell wall synthesis. Our results suggest that human platelets plus anidulafungin might contribute to defense againstA. fumigatus.


mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
L. Zhang ◽  
K. Ramijan ◽  
V. J. Carrión ◽  
L. T. van der Aart ◽  
J. Willemse ◽  
...  

ABSTRACT The cell wall is a stress-bearing structure and a unifying trait in bacteria. Without exception, synthesis of the cell wall involves formation of the precursor molecule lipid II by the activity of the essential biosynthetic enzyme MurG, which is encoded in the division and cell wall synthesis (dcw) gene cluster. Here, we present the discovery of a cell wall enzyme that can substitute for MurG. A mutant of Kitasatospora viridifaciens lacking a significant part of the dcw cluster, including murG, surprisingly produced lipid II and wild-type peptidoglycan. Genomic analysis identified a distant murG homologue, which encodes a putative enzyme that shares only around 31% amino acid sequence identity with MurG. We show that this enzyme can replace the canonical MurG, and we therefore designated it MglA. Orthologues of mglA are present in 38% of all genomes of Kitasatospora and members of the sister genus Streptomyces. CRISPR interference experiments showed that K. viridifaciens mglA can also functionally replace murG in Streptomyces coelicolor, thus validating its bioactivity and demonstrating that it is active in multiple genera. All together, these results identify MglA as a bona fide lipid II synthase, thus demonstrating plasticity in cell wall synthesis. IMPORTANCE Almost all bacteria are surrounded by a cell wall, which protects cells from environmental harm. Formation of the cell wall requires the precursor molecule lipid II, which in bacteria is universally synthesized by the conserved and essential lipid II synthase MurG. We here exploit the unique ability of an actinobacterial strain capable of growing with or without its cell wall to discover an alternative lipid II synthase, MglA. Although this enzyme bears only weak sequence similarity to MurG, it can functionally replace MurG and can even do so in organisms that naturally have only a canonical MurG. The observation that MglA proteins are found in many actinobacteria highlights the plasticity in cell wall synthesis in these bacteria and demonstrates that important new cell wall biosynthetic enzymes remain to be discovered.


2020 ◽  
Author(s):  
Song Chen ◽  
Xin Lin ◽  
Xiyang Zhao ◽  
Su Chen

Abstract BackgroundCellulose is an essential structural component of plant cell wall and is an important resource to produce paper, textiles, bioplastics and other biomaterials. The synthesis of cellulose is among the most important but poorly understood biochemical processes, which is precisely regulated by internal and external cues.ResultsHere, we identified 46 gene models in 7 gene families which encoding cellulose synthase and related enzymes of Betula pendula, and the transcript abundance of these genes in xylem, root, leaf and flower tissues also be determined. Based on these RNA-seq data, we have identified 8 genes that most likely participate in secondary cell wall synthesis, which include 3 cellulose synthase genes and 5 cellulose synthase-like genes. In parallel, a gene co-expression network was also constructed based on transcriptome sequencing.ConclusionsIn this study, we have identified a total of 46 cell wall synthesis genes in B. pendula, which include 8 secondary cell wall synthesis genes. These analyses will help decipher the genetic information of the cell wall synthesis genes, elucidate the molecular mechanism of cellulose synthesis and understand the cell wall structure in B. pendula.


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