scholarly journals Exploring the diverse functions of peptidoglycan hydrolases in the plant pathogen, Agrobacterium tumefaciens

2019 ◽  
Author(s):  
◽  
Wanda Melissa Figueroa-Cuilan
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Agrobacterium Tumefaciens ◽  
Plant Pathogen ◽  
Beta Lactam ◽  
Peptidoglycan Hydrolases ◽  
Cell Wall Hydrolases ◽  
Cell Wall Hydrolysis

The plant pathogen Agrobacterium tumefaciens displays an atypical form of unipolar elongation, followed by incipient pole synthesis during cell division and cell separation. Currently, how polar growing bacteria modulate cell wall hydrolysis during growth and division remains largely unknown. This work includes the comprehensive analysis and characterization of the role of cell wall hydrolyses involved in bacterial growth, division, recycling and beta-lactam resistance in A. tumefaciens. First, we performed bioinformatic analyses and used reverse genetics to better understand the role cell wall hydrolases in A. tumefaciens. Inactivation of most cell wall hydrolases, led to no phenotypic defects suggesting a high degree of redundancy. However, inactivation of the amidase, AmiD, and the lytic transglycosylase Atu3779, revealed significant changes in beta-lactam resistance suggesting that these proteins are involved in the activation beta-lactamases and outer-membrane integrity. Next, we developed a tool (Figueroa-Cuilan et al., 2016) to dissect the role of essential genes, which enabled characterization of the essential regulator of cell division, DipM, a LytM-containing factor. Absence of DipM causes severe cell division defects, including increased cell length, mid-cell width and lysis. A cell wall composition analysis of cells devoid of DipM shows an increase in the activity of the PG hydrolases, lytic transglycosylases, suggesting that DipM may inhibit the activity of these enzymes. Lastly, we find that deletion of individual lytic transglycolsylases (LTs) from the DipM depletion strain delays the onset of the DipM depletion phenotype. Overall, this research provides mechanistic insights about the roles of peptidoglycan hydrolases and their regulators in cell growth and division. Understanding how bacterial cell wall hydrolysis is spatiotemporally regulated and coordinated with cell wall synthesis and cell division (Figueroa-Cuilan and Brown, 2018), will be applicable to other closely related polar-growing bacteria.

scholarly journals Role of Cell Wall Hydrolases in Staphylococcus Aureus Cell Division

2014 ◽  
Vol 106 (2) ◽  
pp. 579a
Author(s):  
Xiaoxue Zhou ◽  
David K. Halladin ◽  
Enrique R. Rojas ◽  
Julie A. Theriot
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cell Division ◽  
Cell Wall Hydrolases

The role of Golgi bodies in polysaccharide sulphation in Fucuszygotes

1978 ◽  
Vol 32 (1) ◽  
pp. 337-356
Author(s):  
M.E. Callow ◽  
S.J. Coughlan ◽  
L.V. Evans
Keyword(s):  
Cell Wall ◽  
Alginic Acid ◽  
Soluble Fraction ◽  
Amorphous Layer ◽  
Acceptor Molecule ◽  
Golgi Bodies ◽  
Isolation And Characterization ◽  
Fucus Serratus

The cell wall of 24-h zygotes of Fucus serratus is composed of 3 layers—an inner fibrillar layer (sulphated fucan), an outer fibrillar layer (alginic aicd/cellulose) and an exterior amorphous layer (sulphated fucan, alginic acid). The 2 layers containing sulphated fucan are preferentially thickened at the rhizoid pole. Light- and electron-microscope autoradiographic pulse-chase experiments on 22-h zygotes using 35SO2-(4) show the Golgi bodies to be the sites of fucan sulphation. The isolation and characterization of isolated Golgi-rich fractions from 22-h zygotes shows that the first detectable labelled macromolecule is associated with these fractions 2 min after addition of 35SO2-(4). The sulphate acceptor molecule has been partially characterized. 35S-APS and 35S-paps are detectable in the soluble fraction 0.5 min after addition of 35SO2-(4). The results are discussed in relation to other published work on the differentiation of Fucus embryos and on polysaccharide sulphation.

scholarly journals Regulation of Pathogenic Spore Germination by CgRac1 in the Fungal Plant Pathogen Colletotrichum gloeosporioides

2011 ◽  
Vol 10 (8) ◽  
pp. 1122-1130 ◽  
Author(s):  
Iris Nesher ◽  
Anna Minz ◽  
Leonie Kokkelink ◽  
Paul Tudzynski ◽  
Amir Sharon
Keyword(s):  
Cell Division ◽  
Plant Pathogen ◽  
Germ Tube ◽  
Colletotrichum Gloeosporioides ◽  
Fluorescent Protein ◽  
Nuclear Division ◽  
Simultaneous Formation ◽  
Content Type ◽  
Germ Tubes

ABSTRACT Colletotrichum gloeosporioides is a facultative plant pathogen: it can live as a saprophyte on dead organic matter or as a pathogen on a host plant. Different patterns of conidial germination have been recognized under saprophytic and pathogenic conditions, which also determine later development. Here we describe the role of CgRac1 in regulating pathogenic germination. The hallmark of pathogenic germination is unilateral formation of a single germ tube following the first cell division. However, transgenic strains expressing a constitutively active CgRac1 (CA-CgRac1) displayed simultaneous formation of two germ tubes, with nuclei continuing to divide in both cells after the first cell division. CA-CgRac1 also caused various other abnormalities, including difficulties in establishing and maintaining cell polarity, reduced conidial and hyphal adhesion, and formation of immature appressoria. Consequently, CA-CgRac1 isolates were completely nonpathogenic. Localization studies with cyan fluorescent protein (CFP)-CgRac1 fusion protein showed that the CgRac1 protein is abundant in conidia and in hyphal tips. Although the CFP signal was equally distributed in both cells of a germinating conidium, reactive oxygen species accumulated only in the cell that produced a germ tube, indicating that CgRac1 was active only in the germinating cell. Collectively, our results show that CgRac1 is a major regulator of asymmetric development and that it is involved in the regulation of both morphogenesis and nuclear division. Modification of CgRac1 activity disrupts the morphogenetic program and prevents fungal infection.

Characterization of the cell wall of the ubiquitous plant pathogen Botrytis cinerea

2009 ◽  
Vol 113 (12) ◽  
pp. 1396-1403 ◽  
Author(s):  
Dario Cantu ◽  
L. Carl Greve ◽  
John M. Labavitch ◽  
Ann L.T. Powell
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Plant Pathogen

scholarly journals The Antituberculosis Drug Ethambutol Selectively Blocks Apical Growth in CMN Group Bacteria

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Karin Schubert ◽  
Boris Sieger ◽  
Fabian Meyer ◽  
Giacomo Giacomelli ◽  
Kati Böhm ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Cell Growth ◽  
Antibiotic Treatment ◽  
Bacterial Infections ◽  
Apical Cell ◽  
Combined Treatment ◽  
Mycolic Acid ◽  
Cell Wall Synthesis ◽  
Beta Lactam

ABSTRACT Members of the genus Mycobacterium are the most prevalent cause of infectious diseases. Mycobacteria have a complex cell envelope containing a peptidoglycan layer and an additional arabinogalactan polymer to which a mycolic acid bilayer is linked; this complex, multilayered cell wall composition (mAGP) is conserved among all CMN group bacteria. The arabinogalactan and mycolic acid synthesis pathways constitute effective drug targets for tuberculosis treatment. Ethambutol (EMB), a classical antituberculosis drug, inhibits the synthesis of the arabinose polymer. Although EMB acts bacteriostatically, its underlying molecular mechanism remains unclear. Here, we used Corynebacterium glutamicum and Mycobacterium phlei as model organisms to study the effects of EMB at the single-cell level. Our results demonstrate that EMB specifically blocks apical cell wall synthesis, but not cell division, explaining the bacteriostatic effect of EMB. Furthermore, the data suggest that members of the family Corynebacterineae have two dedicated machineries for cell elongation (elongasome) and cytokinesis (divisome). IMPORTANCE Antibiotic treatment of bacterial pathogens has contributed enormously to the increase in human health. Despite the apparent importance of antibiotic treatment of bacterial infections, surprisingly little is known about the molecular functions of antibiotic actions in the bacterial cell. Here, we analyzed the molecular effects of ethambutol, a first-line antibiotic against infections caused by members of the genus Mycobacterium. We find that this drug selectively blocks apical cell growth but still allows for effective cytokinesis. As a consequence, cells survive ethambutol treatment and adopt a pneumococcal cell growth mode with cell wall synthesis only at the site of cell division. However, combined treatment of ethambutol and beta-lactam antibiotics acts synergistically and effectively stops cell proliferation. IMPORTANCE Antibiotic treatment of bacterial pathogens has contributed enormously to the increase in human health. Despite the apparent importance of antibiotic treatment of bacterial infections, surprisingly little is known about the molecular functions of antibiotic actions in the bacterial cell. Here, we analyzed the molecular effects of ethambutol, a first-line antibiotic against infections caused by members of the genus Mycobacterium. We find that this drug selectively blocks apical cell growth but still allows for effective cytokinesis. As a consequence, cells survive ethambutol treatment and adopt a pneumococcal cell growth mode with cell wall synthesis only at the site of cell division. However, combined treatment of ethambutol and beta-lactam antibiotics acts synergistically and effectively stops cell proliferation.

scholarly journals Reactive oxygen species as important regulators of cell division

2020 ◽  
Author(s):  
Weiliang Qi ◽  
Li Ma ◽  
Fei Wang ◽  
Ping Wang ◽  
Junyan Wu ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Wall ◽  
Cell Division ◽  
Cold Stress ◽  
Reactive Oxygen ◽  
Vascular Bundles ◽  
Oxygen Species ◽  
Root Primordia ◽  
Lateral Root Primordia

AbstractCurrently, the role of reactive oxygen species (ROS) in plant growth is a topic of interest. In this study, we discuss the role of ROS in cell division. We analyzed ROS’ impact on the stiffness of plant cell walls and whether ROS play an important role in Brassica napus’ ability to adapt to cold stress. Cultivated sterile seedlings and calli of cold-tolerant cultivar 16NTS309 were subjected to cold stress at 25°C and 4°C, respectively. Under normal conditions, O2.− mainly accumulated in the leaf edges, shoot apical meristem, leaf primordia, root tips, lateral root primordia, calli of meristematic nodular tissues, cambia, vascular bundles and root primordia, which are characterized by high division rates. After exposure to cold stress, the malondialdehyde and ROS (O2.−) contents in roots, stems and leaves of cultivar 16NTS309 were significantly higher than under non-cold conditions (P < 0.05). ROS (O2.−) were not only distributed in these zones, but also in other cells, at higher levels than under normal conditions. A strong ROS-based staining appeared in the cell wall. The results support a dual role for apoplastic ROS, in which they have direct effects on the stiffness of the cell wall, because ROS cleave cell-wall, and act as wall loosening agents, thereby either promoting or restricting cellular division. This promotes the appearance of new shoots and a strong root system, allowing plants to adapt to cold stress.

scholarly journals Direct and indirect interactions promote complexes of the lipoprotein LbcA, the CtpA protease and its substrates, and other cell wall proteins in Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Dolonchapa Chakraborty ◽  
Andrew J Darwin
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Type Iii Secretion ◽  
Protein Complexes ◽  
Peptidoglycan Hydrolases ◽  
Carboxyl Terminal ◽  
Processing Protease ◽  
Enzyme Complexes

The Pseudomonas aeruginosa lipoprotein LbcA was discovered because it copurified with and promoted the activity of CtpA, a carboxyl-terminal processing protease (CTP) required for type III secretion system function, and for virulence in a mouse model of acute pneumonia. In this study we explored the role of LbcA by determining its effect on the proteome and its participation in protein complexes. lbcA and ctpA null mutations had strikingly similar effects on the proteome, suggesting that facilitating CtpA might be the most impactful role of LbcA in the bacterial cell. Independent complexes containing LbcA and CtpA, or LbcA and substrate, were isolated from P. aeruginosa cells, indicating that LbcA facilitates proteolysis by recruiting the protease and its substrates independently. An unbiased examination of proteins that copurified with LbcA revealed an enrichment for proteins associated with the cell wall. One of these copurification partners was found to be a new CtpA substrate, and the first substrate that is not a peptidoglycan hydrolase. Many of the other LbcA copurification partners are known or predicted peptidoglycan hydrolases. However, some of these LbcA copurification partners were not cleaved by CtpA, and an in vitro assay revealed that while CtpA and all of its substrates bound to LbcA directly, these non-substrates did not. Subsequent experiments suggested that the non substrates might co-purify with LbcA by participating in multi-enzyme complexes containing LbcA-binding CtpA substrates.

scholarly journals Characterization of O-Acetylation of N-Acetylglucosamine

2011 ◽  
Vol 286 (27) ◽  
pp. 23950-23958 ◽  
Author(s):  
Elvis Bernard ◽  
Thomas Rolain ◽  
Pascal Courtin ◽  
Alain Guillot ◽  
Philippe Langella ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Characterization ◽  
Bacterial Species ◽  
Muramic Acid ◽  
Gram Positive Bacteria ◽  
Mutant Strains ◽  
Encoding Genes ◽  
Hydrolysis Of ◽  
Cell Wall Hydrolysis

Peptidoglycan (PG) N-acetyl muramic acid (MurNAc) O-acetylation is widely spread in Gram-positive bacteria and is generally associated with resistance against lysozyme and endogenous autolysins. We report here the presence of O-acetylation on N-acetylglucosamine (GlcNAc) in Lactobacillus plantarum PG. This modification of glycan strands was never described in bacteria. Fine structural characterization of acetylated muropeptides released from L. plantarum PG demonstrated that both MurNAc and GlcNAc are O-acetylated in this species. These two PG post-modifications rely on two dedicated O-acetyltransferase encoding genes, named oatA and oatB, respectively. By analyzing the resistance to cell wall hydrolysis of mutant strains, we showed that GlcNAc O-acetylation inhibits N-acetylglucosaminidase Acm2, the major L. plantarum autolysin. In this bacterial species, inactivation of oatA, encoding MurNAc O-acetyltransferase, resulted in marked sensitivity to lysozyme. Moreover, MurNAc over-O-acetylation was shown to activate autolysis through the putative N-acetylmuramoyl-l-alanine amidase LytH enzyme. Our data indicate that in L. plantarum, two different O-acetyltransferases play original and antagonistic roles in the modulation of the activity of endogenous autolysins.

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