1
|
Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022. MASS SPECTROMETRY REVIEWS 2024. [PMID: 38925550 DOI: 10.1002/mas.21873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 06/28/2024]
Abstract
The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.
Collapse
|
2
|
Willdigg JR, Patel Y, Helmann JD. A Decrease in Fatty Acid Synthesis Rescues Cells with Limited Peptidoglycan Synthesis Capacity. mBio 2023; 14:e0047523. [PMID: 37017514 PMCID: PMC10128001 DOI: 10.1128/mbio.00475-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/13/2023] [Indexed: 04/06/2023] Open
Abstract
Proper synthesis and maintenance of a multilayered cell envelope are critical for bacterial fitness. However, whether mechanisms exist to coordinate synthesis of the membrane and peptidoglycan layers is unclear. In Bacillus subtilis, synthesis of peptidoglycan (PG) during cell elongation is mediated by an elongasome complex acting in concert with class A penicillin-binding proteins (aPBPs). We previously described mutant strains limited in their capacity for PG synthesis due to a loss of aPBPs and an inability to compensate by upregulation of elongasome function. Growth of these PG-limited cells can be restored by suppressor mutations predicted to decrease membrane synthesis. One suppressor mutation leads to an altered function repressor, FapR*, that functions as a super-repressor and leads to decreased transcription of fatty acid synthesis (FAS) genes. Consistent with fatty acid limitation mitigating cell wall synthesis defects, inhibition of FAS by cerulenin also restored growth of PG-limited cells. Moreover, cerulenin can counteract the inhibitory effect of β-lactams in some strains. These results imply that limiting PG synthesis results in impaired growth, in part, due to an imbalance of PG and cell membrane synthesis and that B. subtilis lacks a robust physiological mechanism to reduce membrane synthesis when PG synthesis is impaired. IMPORTANCE Understanding how a bacterium coordinates cell envelope synthesis is essential to fully appreciate how bacteria grow, divide, and resist cell envelope stresses, such as β-lactam antibiotics. Balanced synthesis of the peptidoglycan cell wall and the cell membrane is critical for cells to maintain shape and turgor pressure and to resist external cell envelope threats. Using Bacillus subtilis, we show that cells deficient in peptidoglycan synthesis can be rescued by compensatory mutations that decrease the synthesis of fatty acids. Further, we show that inhibiting fatty acid synthesis with cerulenin is sufficient to restore growth of cells deficient in peptidoglycan synthesis. Understanding the coordination of cell wall and membrane synthesis may provide insights relevant to antimicrobial treatment.
Collapse
Affiliation(s)
| | - Yesha Patel
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| |
Collapse
|
3
|
Abstract
Gram-positive bacterial cells are protected from the environment by a cell envelope that is comprised of a thick layer of peptidoglycan that maintains cell shape and teichoic acid polymers whose biological function remains unclear. In Bacillus subtilis, the 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 lipoteichoic acids (LTAs) and the accumulation of the major autolysin LytE in the cell wall. Our analysis provides further evidence that the length and abundance of LTAs act to regulate the cellular level and activity of autolytic enzymes, specifically LytE. Importantly, we identify a novel function for the aminoacyl-phosphatidylglycerol synthase MprF in the modulation of LTA biosynthesis in both B. subtilis and Staphylococcus aureus. This finding has implications for our understanding of antimicrobial resistance (particularly to daptomycin) in clinically relevant bacteria and the involvement of MprF in the virulence of pathogens such as methicillin-resistant S. aureus (MRSA). IMPORTANCE In Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus, the cell envelope is a structure that protects the cells from the environment but is also dynamic in that it must be modified in a controlled way to allow cell growth. In this study, we show that lipoteichoic acids (LTAs), which are anionic polymers attached to the membrane, have a direct role in modulating the cellular abundance of cell wall-degrading enzymes. We also find that the apparent length of the LTA is modulated by the activity of the enzyme MprF, previously implicated in modifications of the cell membrane leading to resistance to antimicrobial peptides. These findings are important contributions to our understanding of how bacteria balance cell wall synthesis and degradation to permit controlled growth and division. These results also have implications for the interpretation of antibiotic resistance, particularly for the clinical treatment of MRSA infections.
Collapse
|
4
|
Abstract
By chance, we discovered a window of extracellular magnesium (Mg2+) availability that modulates the division frequency of Bacillus subtilis without affecting its growth rate. In this window, cells grown with excess Mg2+ produce shorter cells than do those grown in unsupplemented medium. The Mg2+-responsive adjustment in cell length occurs in both rich and minimal media as well as in domesticated and undomesticated strains. Of other divalent cations tested, manganese (Mn2+) and zinc (Zn2+) also resulted in cell shortening, but this occurred only at concentrations that affected growth. Cell length decreased proportionally with increasing Mg2+ from 0.2 mM to 4.0 mM, with little or no detectable change being observed in labile, intracellular Mg2+, based on a riboswitch reporter. Cells grown in excess Mg2+ had fewer nucleoids and possessed more FtsZ-rings per unit cell length, consistent with the increased division frequency. Remarkably, when shifting cells from unsupplemented to supplemented medium, more than half of the cell length decrease occurred in the first 10 min, consistent with rapid division onset. Relative to unsupplemented cells, cells growing at steady-state with excess Mg2+ showed an enhanced expression of a large number of SigB-regulated genes and the activation of the Fur, MntR, and Zur regulons. Thus, by manipulating the availability of one nutrient, we were able to uncouple the growth rate from the division frequency and identify transcriptional changes that suggest that cell division is accompanied by the general stress response and an enhanced demand to sequester and/or increase the uptake of iron, Mn2+, and Zn2+. IMPORTANCE The signals that cells use to trigger cell division are unknown. Although division is often considered intrinsic to the cell cycle, microorganisms can continue to grow and repeat rounds of DNA replication without dividing, indicating that cycles of division can be skipped. Here, we show that by manipulating a single nutrient, namely, Mg2+, cell division can be uncoupled from the growth rate. This finding can be applied to investigate the nature of the cell division signal(s).
Collapse
|
5
|
Matavacas J, Hallgren J, von Wachenfeldt C. Bacillus subtilis forms twisted cells with cell wall integrity defects upon removal of the molecular chaperones DnaK and trigger factor. Front Microbiol 2023; 13:988768. [PMID: 36726573 PMCID: PMC9886141 DOI: 10.3389/fmicb.2022.988768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/20/2022] [Indexed: 01/18/2023] Open
Abstract
The protein homeostasis network ensures a proper balance between synthesis, folding, and degradation of all cellular proteins. DnaK and trigger factor (TF) are ubiquitous bacterial molecular chaperones that assist in protein folding, as well as preventing protein misfolding and aggregation. In Escherichia coli, DnaK and TF possess partially overlapping functions. Their combined depletion results in proteostasis collapse and is synthetically lethal at temperatures above 30°C. To increase our understanding on how proteostasis is maintained in Gram-positive bacteria, we have investigated the physiological effects of deleting dnaK and tig (encoding for DnaK and TF) in Bacillus subtilis. We show that combined deletion of dnaK and tig in B. subtilis is non-lethal, but causes a severe pleiotropic phenotype, including an aberrant twisted and filamentous cell morphology, as well as decreased tolerance to heat and to cell wall active antibiotics and hydrolytic enzymes, indicative of defects in cell wall integrity. In addition, cells lacking DnaK and TF have a much smaller colony size due to defects in motility. Despite these physiological changes, we observed no major compromises in important cellular processes such as cell growth, FtsZ localization and division and only moderate defects in spore formation. Finally, through suppressor analyses, we found that the wild-type cell shape can be partially restored by mutations in genes involved in metabolism or in other diverse cellular processes.
Collapse
|
6
|
Schulz LM, Rothe P, Halbedel S, Gründling A, Rismondo J. Imbalance of peptidoglycan biosynthesis alters the cell surface charge of Listeria monocytogenes. Cell Surf 2022; 8:100085. [PMID: 36304571 PMCID: PMC9593813 DOI: 10.1016/j.tcsw.2022.100085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 02/09/2023] Open
Abstract
The bacterial cell wall is composed of a thick layer of peptidoglycan and cell wall polymers, which are either embedded in the membrane or linked to the peptidoglycan backbone and referred to as lipoteichoic acid (LTA) and wall teichoic acid (WTA), respectively. Modifications of the peptidoglycan or WTA backbone can alter the susceptibility of the bacterial cell towards cationic antimicrobials and lysozyme. The human pathogen Listeria monocytogenes is intrinsically resistant towards lysozyme, mainly due to deacetylation and O-acetylation of the peptidoglycan backbone via PgdA and OatA. Recent studies identified additional factors, which contribute to the lysozyme resistance of this pathogen. One of these is the predicted ABC transporter, EslABC. An eslB mutant is hyper-sensitive towards lysozyme, likely due to the production of thinner and less O-acetylated peptidoglycan. Using a suppressor screen, we show here that suppression of eslB phenotypes could be achieved by enhancing peptidoglycan biosynthesis, reducing peptidoglycan hydrolysis or alterations in WTA biosynthesis and modification. The lack of EslB also leads to a higher negative surface charge, which likely stimulates the activity of peptidoglycan hydrolases and lysozyme. Based on our results, we hypothesize that the portion of cell surface exposed WTA is increased in the eslB mutant due to the thinner peptidoglycan layer and that latter one could be caused by an impairment in UDP-N-acetylglucosamine (UDP-GlcNAc) production or distribution.
Collapse
Affiliation(s)
- Lisa Maria Schulz
- Department of General Microbiology, Institute of Microbiology and Genetics, GZMB, Georg-August University Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany
| | - Patricia Rothe
- FG11, Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Sven Halbedel
- FG11, Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Burgstraße 37, 38855 Wernigerode, Germany
- Institute for Medical Microbiology and Hospital Hygiene, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany
| | - Angelika Gründling
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jeanine Rismondo
- Department of General Microbiology, Institute of Microbiology and Genetics, GZMB, Georg-August University Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| |
Collapse
|
7
|
Kepplinger B, Wen X, Tyler AR, Kim BY, Brown J, Banks P, Dashti Y, Mackenzie ES, Wills C, Kawai Y, Waldron KJ, Allenby NEE, Wu LJ, Hall MJ, Errington J. Mirubactin C rescues the lethal effect of cell wall biosynthesis mutations in Bacillus subtilis. Front Microbiol 2022; 13:1004737. [PMID: 36312962 PMCID: PMC9609785 DOI: 10.3389/fmicb.2022.1004737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/22/2022] [Indexed: 01/29/2023] Open
Abstract
Growth of most rod-shaped bacteria is accompanied by the insertion of new peptidoglycan into the cylindrical cell wall. This insertion, which helps maintain and determine the shape of the cell, is guided by a protein machine called the rod complex or elongasome. Although most of the proteins in this complex are essential under normal growth conditions, cell viability can be rescued, for reasons that are not understood, by the presence of a high (mM) Mg2+ concentration. We screened for natural product compounds that could rescue the growth of mutants affected in rod-complex function. By screening > 2,000 extracts from a diverse collection of actinobacteria, we identified a compound, mirubactin C, related to the known iron siderophore mirubactin A, which rescued growth in the low micromolar range, and this activity was confirmed using synthetic mirubactin C. The compound also displayed toxicity at higher concentrations, and this effect appears related to iron homeostasis. However, several lines of evidence suggest that the mirubactin C rescuing activity is not due simply to iron sequestration. The results support an emerging view that the functions of bacterial siderophores extend well beyond simply iron binding and uptake.
Collapse
Affiliation(s)
- Bernhard Kepplinger
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Xin Wen
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Andrew Robert Tyler
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Byung-Yong Kim
- Odyssey Therapeutics Inc., Newcastle upon Tyne, United Kingdom
| | - James Brown
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Peter Banks
- Faculty of Medical Sciences, Bioscience Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Yousef Dashti
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Eilidh Sohini Mackenzie
- Faculty of Medical Sciences, Bioscience Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Corinne Wills
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Yoshikazu Kawai
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Kevin John Waldron
- Faculty of Medical Sciences, Bioscience Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Michael John Hall
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
- Odyssey Therapeutics Inc., Newcastle upon Tyne, United Kingdom
| |
Collapse
|
8
|
MraZ Transcriptionally Controls the Critical Level of FtsL Required for Focusing Z-Rings and Kickstarting Septation in Bacillus subtilis. J Bacteriol 2022; 204:e0024322. [PMID: 35943250 PMCID: PMC9487581 DOI: 10.1128/jb.00243-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterial division and cell wall (dcw) cluster is a highly conserved region of the genome which encodes several essential cell division factors, including the central divisome protein FtsZ. Understanding the regulation of this region is key to our overall understanding of the division process. mraZ is found at the 5' end of the dcw cluster, and previous studies have described MraZ as a sequence-specific DNA binding protein. In this article, we investigate MraZ to elucidate its role in Bacillus subtilis. Through our investigation, we demonstrate that increased levels of MraZ result in lethal filamentation due to repression of its own operon (mraZ-mraW-ftsL-pbpB). We observed rescue of filamentation upon decoupling ftsL expression, but not other genes in the operon, from MraZ control. Our data suggest that regulation of the mra operon may be an alternative way for cells to quickly arrest cytokinesis, potentially during entry into the stationary phase and in the event of DNA replication arrest. Furthermore, through time-lapse microscopy, we were able to identify that overexpression of mraZ or depletion of FtsL results in decondensation of the FtsZ ring (Z-ring). Using fluorescent d-amino acid labeling, we also observed that coordinated peptidoglycan insertion at the division site is dysregulated in the absence of FtsL. Thus, we reveal that the precise role of FtsL is in Z-ring maturation and focusing septal peptidoglycan synthesis. IMPORTANCE MraZ is a highly conserved protein found in a diverse range of bacteria, including genome-reduced Mycoplasma. We investigated the role of MraZ in Bacillus subtilis and found that overproduction of MraZ is toxic due to cell division inhibition. Upon further analysis, we observed that MraZ is a repressor of its own operon, which includes genes that encode the essential cell division factors FtsL and PBP2B. We noted that decoupling of ftsL alone was sufficient to abolish MraZ-mediated cell division inhibition. Using time-lapse microscopy, we showed that under conditions where the FtsL level is depleted, the cell division machinery is unable to initiate cytokinesis. Thus, our results pinpoint that the precise role of FtsL is in concentrating septal cell wall synthesis to facilitate cell division.
Collapse
|