Cell Wall Biogenesis During Elongation and Division in the Plant Pathogen Agrobacterium tumefaciens

2018 ◽  
pp. 87-110 ◽  
Author(s):  
Wanda M. Figueroa-Cuilan ◽  
Pamela J. B. Brown
Keyword(s):  
Cell Wall ◽  
Agrobacterium Tumefaciens ◽  
Plant Pathogen ◽  
Cell Wall Biogenesis

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 PopZ and FtsZ coordinate polar growth termination and cell division in Agrobacterium tumefaciens

2018 ◽  
Author(s):  
◽  
Matthew (Matthew Lloyd) Howell
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Agrobacterium Tumefaciens ◽  
Chromosome Segregation ◽  
Morphological Changes ◽  
Genetic Material ◽  
Fluorescent Labeling ◽  
Scaffolding Proteins ◽  
Polar Growth ◽  
Cell Wall Biogenesis

Understanding how bacterial cells expand their cell walls is an important question with relevance to development of antibiotics. While many studies have focused on the regulation of bacterial elongation utilizing lateral cell wall biogenesis, polar growth in bacteria is less well understood. Yet, polar growth has been observed across taxonomically diverse bacteria like Actinobacteria and the alphaproteobacterial clade Rhizobiales (Howell and Brown, 2016). Interestingly, polar-growing bacteria within Rhizobiales lack canonical scaffolding proteins for spatial and temporal regulation of peptidoglycan synthesis during elongation. Here, we dissect the role of two candidate scaffolding proteins in directing cell wall synthesis in the bacterial plant pathogen, Agrobacterium tumefaciens. Since cell wall (peptidoglycan) biosynthesis during elongation and cell division is vital for bacterial survival, we expected many key proteins involved in these processes to be essential for cell survival. Thus, we developed a depletion system for A. tumefaciens (Figureroa-Cuilan et al. 2016). We further optimized a suite of target-specific fluorescent labeling techniques which allow us to visualize morphological changes during essential cell processes (Howell, Daniel, and Brown, 2017). We use these techniques to dissect the contributions of PopZ and FtsZ to polar growth and cell division. Although PopZ is not required for polar growth, it is required for proper coordination of polar growth, chromosome segregation, and cell division. This PopZ-mediated coordination ensures that daughter cells are the proper size and contain a complete complement of genetic material (Howell et al 2017). Next, we find that FtsZ is required for both termination of polar growth and cell division. This finding suggests that FtsZ has at least two important functions in regulation of cell wall biogenesis. First, FtsZ enables cell wall biogenesis machinery to be released or inactivated from the growth pole. Second, FtsZ must recruit additional proteins to mid cell to assemble the divisome, enabling activation of cell wall biogenesis to promote septum formation and cell separation. While further research is needed to understand how growth is targeted to the pole during elongation, our work provides mechanistic insights about the coordination of polar growth termination, chromosome segregation, and cell division. We hypothesize that our findings will be applicable to other closely related polar growing Rhizobiales, including plant, animal, and human pathogens.

scholarly journals Microtubule Dynamics Plays a Vital Role in Plant Adaptation and Tolerance to Salt Stress

2021 ◽  
Vol 22 (11) ◽  
pp. 5957
Author(s):  
Hyun Jin Chun ◽  
Dongwon Baek ◽  
Byung Jun Jin ◽  
Hyun Min Cho ◽  
Mi Suk Park ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Salt Stress ◽  
Differentially Expressed ◽  
Differentially Expressed Proteins ◽  
Related Gene ◽  
Plant Adaptation ◽  
Salt Stress Response ◽  
Network Analyses ◽  
Cell Wall Biogenesis

Although recent studies suggest that the plant cytoskeleton is associated with plant stress responses, such as salt, cold, and drought, the molecular mechanism underlying microtubule function in plant salt stress response remains unclear. We performed a comparative proteomic analysis between control suspension-cultured cells (A0) and salt-adapted cells (A120) established from Arabidopsis root callus to investigate plant adaptation mechanisms to long-term salt stress. We identified 50 differentially expressed proteins (45 up- and 5 down-regulated proteins) in A120 cells compared with A0 cells. Gene ontology enrichment and protein network analyses indicated that differentially expressed proteins in A120 cells were strongly associated with cell structure-associated clusters, including cytoskeleton and cell wall biogenesis. Gene expression analysis revealed that expressions of cytoskeleton-related genes, such as FBA8, TUB3, TUB4, TUB7, TUB9, and ACT7, and a cell wall biogenesis-related gene, CCoAOMT1, were induced in salt-adapted A120 cells. Moreover, the loss-of-function mutant of Arabidopsis TUB9 gene, tub9, showed a hypersensitive phenotype to salt stress. Consistent overexpression of Arabidopsis TUB9 gene in rice transgenic plants enhanced tolerance to salt stress. Our results suggest that microtubules play crucial roles in plant adaptation and tolerance to salt stress. The modulation of microtubule-related gene expression can be an effective strategy for developing salt-tolerant crops.

scholarly journals The Transcription Factor Con7-1 Is a Master Regulator of Morphogenesis and Virulence in Fusarium oxysporum

2015 ◽  
Vol 28 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Carmen Ruiz-Roldán ◽  
Yolanda Pareja-Jaime ◽  
José Antonio González-Reyes ◽  
M. Isabel G. Roncero
Keyword(s):  
Cell Wall ◽  
Fusarium Oxysporum ◽  
Gene Expression Analysis ◽  
Wall Structure ◽  
Targeted Deletion ◽  
Signal Perception ◽  
Cell Wall Biogenesis ◽  
Primary And Secondary Metabolism ◽  
Genes Encoding

Previous studies have demonstrated the essential role of morphogenetic regulation in Fusarium oxysporum pathogenesis, including processes such as cell-wall biogenesis, cell division, and differentiation of infection-like structures. We identified three F. oxysporum genes encoding predicted transcription factors showing significant identities to Magnaporthe oryzae Con7p, Con7-1, plus two identical copies of Con7-2. Targeted deletion of con7-1 produced nonpathogenic mutants with altered morphogenesis, including defects in cell wall structure, polar growth, hyphal branching, and conidiation. By contrast, simultaneous inactivation of both con7-2 copies caused no detectable defects in the resulting mutants. Comparative microarray-based gene expression analysis indicated that Con7-1 modulates the expression of a large number of genes involved in different biological functions, including host–pathogen interactions, morphogenesis and development, signal perception and transduction, transcriptional regulation, and primary and secondary metabolism. Taken together, our results point to Con7-1 as general regulator of morphogenesis and virulence in F. oxysporum.

scholarly journals Extracellular Glycanases of Rhizobium leguminosarum Are Activated on the Cell Surface by an Exopolysaccharide-Related Component

2000 ◽  
Vol 182 (5) ◽  
pp. 1304-1312 ◽  
Author(s):  
Angeles Zorreguieta ◽  
Christine Finnie ◽  
J. Allan Downie
Keyword(s):  
Cell Wall ◽  
Agrobacterium Tumefaciens ◽  
Cell Surface ◽  
Rhizobium Leguminosarum ◽  
Plant Cell Wall ◽  
Agar Medium ◽  
Wild Type ◽  
Close Proximity ◽  
Mutant Strains ◽  
Colony Surface

ABSTRACT Rhizobium leguminosarum secretes two extracellular glycanases, PlyA and PlyB, that can degrade exopolysaccharide (EPS) and carboxymethyl cellulose (CMC), which is used as a model substrate of plant cell wall cellulose polymers. When grown on agar medium, CMC degradation occurred only directly below colonies of R. leguminosarum, suggesting that the enzymes remain attached to the bacteria. Unexpectedly, when a PlyA-PlyB-secreting colony was grown in close proximity to mutants unable to produce or secrete PlyA and PlyB, CMC degradation occurred below that part of the mutant colonies closest to the wild type. There was no CMC degradation in the region between the colonies. By growing PlyB-secreting colonies on a lawn of CMC-nondegrading mutants, we could observe a halo of CMC degradation around the colony. Using various mutant strains, we demonstrate that PlyB diffuses beyond the edge of the colony but does not degrade CMC unless it is in contact with the appropriate colony surface. PlyA appears to remain attached to the cells since no such diffusion of PlyA activity was observed. EPS defective mutants could secrete both PlyA and PlyB, but these enzymes were inactive unless they came into contact with an EPS+ strain, indicating that EPS is required for activation of PlyA and PlyB. However, we were unable to activate CMC degradation with a crude EPS fraction, indicating that activation of CMC degradation may require an intermediate in EPS biosynthesis. Transfer of PlyB to Agrobacterium tumefaciens enabled it to degrade CMC, but this was only observed if it was grown on a lawn ofR. leguminosarum. This indicates that the surface ofA. tumefaciens is inappropriate to activate CMC degradation by PlyB. Analysis of CMC degradation by other rhizobia suggests that activation of secreted glycanases by surface components may occur in other species.

scholarly journals The Cek1 and Hog1 Mitogen-Activated Protein Kinases Play Complementary Roles in Cell Wall Biogenesis and Chlamydospore Formation in the Fungal Pathogen Candida albicans

2006 ◽  
Vol 5 (2) ◽  
pp. 347-358 ◽  
Author(s):  
B. Eisman ◽  
R. Alonso-Monge ◽  
E. Román ◽  
D. Arana ◽  
C. Nombela ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Map Kinase ◽  
Fungal Pathogen ◽  
Hog Pathway ◽  
Cell Wall Biogenesis ◽  
Chlamydospore Formation ◽  
Mitogen Activated Protein ◽  
Morphological Transitions ◽  
Relationship Of

ABSTRACT The Hog1 mitogen-activated protein (MAP) kinase mediates an adaptive response to both osmotic and oxidative stress in the fungal pathogen Candida albicans. This protein also participates in two distinct morphogenetic processes, namely the yeast-to-hypha transition (as a repressor) and chlamydospore formation (as an inducer). We show here that repression of filamentous growth occurs both under serum limitation and under other partially inducing conditions, such as low temperature, low pH, or nitrogen starvation. To understand the relationship of the HOG pathway to other MAP kinase cascades that also play a role in morphological transitions, we have constructed and characterized a set of double mutants in which we deleted both the HOG1 gene and other signaling elements (the CST20, CLA4, and HST7 kinases, the CPH1 and EFG1 transcription factors, and the CPP1 protein phosphatase). We also show that Hog1 prevents the yeast-to-hypha switch independent of all the elements analyzed and that the inability of the hog1 mutants to form chlamydospores is suppressed when additional elements of the CEK1 pathway (CST20 or HST7) are altered. Finally, we report that Hog1 represses the activation of the Cek1 MAP kinase under basal conditions and that Cek1 activation correlates with resistance to certain cell wall inhibitors (such as Congo red), demonstrating a role for this pathway in cell wall biogenesis.

scholarly journals Cell wall biogenesis of Arabidopsis thaliana elongating cells: transcriptomics complements proteomics

BMC Genomics ◽  
2009 ◽  
Vol 10 (1) ◽  
pp. 505 ◽  
Author(s):  
Elisabeth Jamet ◽  
David Roujol ◽  
Hélène San-Clemente ◽  
Muhammad Irshad ◽  
Ludivine Soubigou-Taconnat ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Wall Biogenesis
Sign in / Sign up

Export Citation Format

Share Document