scholarly journals Identification of MEDIATOR16 as the Arabidopsis COBRA suppressor MONGOOSE1

2015 ◽  
Vol 112 (52) ◽  
pp. 16048-16053 ◽  
Author(s):  
Nadav Sorek ◽  
Heidi Szemenyei ◽  
Hagit Sorek ◽  
Abigail Landers ◽  
Heather Knight ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcriptome Analysis ◽  
Pectin Methylesterase ◽  
Cell Wall Integrity ◽  
Cellulose Biosynthesis ◽  
Wild Type ◽  
Growth Defects ◽  
Genetic Suppressors ◽  
Biosynthesis Inhibitors

We performed a screen for genetic suppressors of cobra, an Arabidopsis mutant with defects in cellulose formation and an increased ratio of unesterified/esterified pectin. We identified a suppressor named mongoose1 (mon1) that suppressed the growth defects of cobra, partially restored cellulose levels, and restored the esterification ratio of pectin to wild-type levels. mon1 was mapped to the MEDIATOR16 (MED16) locus, a tail mediator subunit, also known as SENSITIVE TO FREEZING6 (SFR6). When separated from the cobra mutation, mutations in MED16 caused resistance to cellulose biosynthesis inhibitors, consistent with their ability to suppress the cobra cellulose deficiency. Transcriptome analysis revealed that a number of cell wall genes are misregulated in med16 mutants. Two of these genes encode pectin methylesterase inhibitors, which, when ectopically expressed, partially suppressed the cobra phenotype. This suggests that cellulose biosynthesis can be affected by the esterification levels of pectin, possibly through modifying cell wall integrity or the interaction of pectin and cellulose.

scholarly journals Inhibition of cell expansion enhances cortical microtubule stability in the root apex of Arabidopsis thaliana

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Veronica Giourieva ◽  
Emmanuel Panteris
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Expansion ◽  
Cortical Microtubule ◽  
Root Apex ◽  
Cellulose Synthase ◽  
Cellulose Biosynthesis ◽  
Cortical Microtubules ◽  
Wild Type ◽  
Microtubule Stability

Abstract Background Cortical microtubules regulate cell expansion by determining cellulose microfibril orientation in the root apex of Arabidopsis thaliana. While the regulation of cell wall properties by cortical microtubules is well studied, the data on the influence of cell wall to cortical microtubule organization and stability remain scarce. Studies on cellulose biosynthesis mutants revealed that cortical microtubules depend on Cellulose Synthase A (CESA) function and/or cell expansion. Furthermore, it has been reported that cortical microtubules in cellulose-deficient mutants are hypersensitive to oryzalin. In this work, the persistence of cortical microtubules against anti-microtubule treatment was thoroughly studied in the roots of several cesa mutants, namely thanatos, mre1, any1, prc1-1 and rsw1, and the Cellulose Synthase Interacting 1 protein (csi1) mutant pom2-4. In addition, various treatments with drugs affecting cell expansion were performed on wild-type roots. Whole mount tubulin immunolabeling was applied in the above roots and observations were performed by confocal microscopy. Results Cortical microtubules in all mutants showed statistically significant increased persistence against anti-microtubule drugs, compared to those of the wild-type. Furthermore, to examine if the enhanced stability of cortical microtubules was due to reduced cellulose biosynthesis or to suppression of cell expansion, treatments of wild-type roots with 2,6-dichlorobenzonitrile (DCB) and Congo red were performed. After these treatments, cortical microtubules appeared more resistant to oryzalin, than in the control. Conclusions According to these findings, it may be concluded that inhibition of cell expansion, irrespective of the cause, results in increased microtubule stability in A. thaliana root. In addition, cell expansion does not only rely on cortical microtubule orientation but also plays a regulatory role in microtubule dynamics, as well. Various hypotheses may explain the increased cortical microtubule stability under decreased cell expansion such as the role of cell wall sensors and the presence of less dynamic cortical microtubules.

scholarly journals Putative PmrA and PmcA are important for normal growth, morphogenesis and cell wall integrity, but not for viability in Aspergillus nidulans

Microbiology ◽  
2014 ◽  
Vol 160 (11) ◽  
pp. 2387-2395 ◽  
Author(s):  
Hechun Jiang ◽  
Feifei Liu ◽  
Shizhu Zhang ◽  
Ling Lu
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Aspergillus Nidulans ◽  
Normal Growth ◽  
Cell Wall Integrity ◽  
Plasma Membrane Atpase ◽  
Growth Defects ◽  
Double Deletion ◽  
Intracellular Ca ◽  
P Type

P-type Ca2+-transporting ATPases are Ca2+ pumps, extruding cytosolic Ca2+ to the extracellular environment or the intracellular Ca2+ store lumens. In budding yeast, Pmr1 (plasma membrane ATPase related), and Pmc1 (plasma membrane calcium-ATPase) cannot be deleted simultaneously for it to survive in standard medium. Here, we deleted two putative Ca2+ pumps, designated AnPmrA and AnPmcA, from Aspergillus nidulans, and obtained the mutants ΔanpmrA and ΔanpmcA, respectively. Then, using ΔanpmrA as the starting strain, the promoter of its anpmcA was replaced with the alcA promoter to secure the mutant ΔanpmrAalcApmcA or its anpmcA was deleted completely to produce the mutant ΔanpmrAΔpmcA. Different from the case in Saccharomyces cerevisiae, double deletion of anpmrA and anpmcA was not lethal in A. nidulans. In addition, deletion of anpmrA and/or anpmcA had produced growth defects, although overexpression of AnPmc1 in ΔanpmrAalcApmcA could not restore the growth defects that resulted from the loss of AnPmrA. Moreover, we found AnPmrA was indispensable for maintenance of normal morphogenesis, especially in low-Ca2+/Mn2+ environments. Thus, our findings suggest AnPmrA and AnPmcA might play important roles in growth, morphogenesis and cell wall integrity in A. nidulans in a different way from that in yeasts.

scholarly journals Aspergillus nidulans Protein O-Mannosyltransferases Play Roles in Cell Wall Integrity and Developmental Patterning

2009 ◽  
Vol 8 (10) ◽  
pp. 1475-1485 ◽  
Author(s):  
Thanyanuch Kriangkripipat ◽  
Michelle Momany
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Double Mutant ◽  
Elevated Temperatures ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Spatial Cues ◽  
Developmental Patterning ◽  
In The Wild ◽  
Increased Sensitivity

ABSTRACT Protein O-mannosyltransferases (Pmts) initiate O-mannosyl glycan biosynthesis from Ser and Thr residues of target proteins. Fungal Pmts are divided into three subfamilies, Pmt1, -2, and -4. Aspergillus nidulans possesses a single representative of each Pmt subfamily, pmtA (subfamily 2), pmtB (subfamily 1), and pmtC (subfamily 4). In this work, we show that single Δpmt mutants are viable and have unique phenotypes and that the ΔpmtA ΔpmtB double mutant is the only viable double mutant. This makes A. nidulans the first fungus in which all members of individual Pmt subfamilies can be deleted without loss of viability. At elevated temperatures, all A. nidulans Δpmt mutants show cell wall-associated defects and increased sensitivity to cell wall-perturbing agents. The Δpmt mutants also show defects in developmental patterning. Germ tube emergence is early in ΔpmtA and more frequent in ΔpmtC mutants than in the wild type. In ΔpmtB mutants, intrahyphal hyphae develop. All Δpmt mutants show distinct conidiophore defects. The ΔpmtA strain has swollen vesicles and conidiogenous cells, the ΔpmtB strain has swollen conidiophore stalks, and the ΔpmtC strain has dramatically elongated conidiophore stalks. We also show that AN5660, an ortholog of Saccharomyces cerevisiae Wsc1p, is modified by PmtA and PmtC. The Δpmt phenotypes at elevated temperatures, increased sensitivity to cell wall-perturbing agents and restoration to wild-type growth with osmoticum suggest that A. nidulans Pmts modify proteins in the cell wall integrity pathway. The altered developmental patterns in Δpmt mutants suggest that A. nidulans Pmts modify proteins that serve as spatial cues.

scholarly journals Differential Regulation of the Cell Wall Integrity Mitogen-Activated Protein Kinase Pathway in Budding Yeast by the Protein Tyrosine Phosphatases Ptp2 and Ptp3

1999 ◽  
Vol 19 (11) ◽  
pp. 7651-7660 ◽  
Author(s):  
Christopher P. Mattison ◽  
Scott S. Spencer ◽  
Kurt A. Kresge ◽  
Ji Lee ◽  
Irene M. Ota
Keyword(s):  
Cell Wall ◽  
Protein Tyrosine Phosphatases ◽  
Negative Regulator ◽  
Cell Wall Integrity ◽  
Dependent Manner ◽  
Tyrosine Phosphatases ◽  
Protein Tyrosine ◽  
Growth Defects ◽  
Mitogen Activated Protein

ABSTRACT Mitogen-activated protein kinases (MAPKs) are inactivated by dual-specificity and protein tyrosine phosphatases (PTPs) in yeasts. InSaccharomyces cerevisiae, two PTPs, Ptp2 and Ptp3, inactivate the MAPKs, Hog1 and Fus3, with different specificities. To further examine the functions and substrate specificities of Ptp2 and Ptp3, we tested whether they could inactivate a third MAPK, Mpk1, in the cell wall integrity pathway. In vivo and in vitro evidence indicates that both PTPs inactivate Mpk1, but Ptp2 is the more effective negative regulator. Multicopy expression of PTP2, but not PTP3, suppressed growth defects due to the MEK kinase mutation, BCK1-20, and the MEK mutation,MKK1-386, that hyperactivate this pathway. In addition, deletion of PTP2, but not PTP3, exacerbated growth defects due to MKK1-386. Other evidence supported a role for Ptp3 in this pathway. Expression of MKK1-386 was lethal in the ptp2Δ ptp3Δ strain but not in either single PTP deletion strain. In addition, the ptp2Δ ptp3Δ strain showed higher levels of heat stress-induced Mpk1-phosphotyrosine than the wild-type strain or strains lacking either PTP. The PTPs also showed differences in vitro. Ptp2 was more efficient than Ptp3 at binding and dephosphorylating Mpk1. Another factor that may contribute to the greater effectiveness of Ptp2 is its subcellular localization. Ptp2 is predominantly nuclear whereas Ptp3 is cytoplasmic, suggesting that active Mpk1 is present in the nucleus. Last, PTP2 but not PTP3 transcript increased in response to heat shock in a Mpk1-dependent manner, suggesting that Ptp2 acts in a negative feedback loop to inactivate Mpk1.

scholarly journals Cross Talk between the Cell Wall Integrity and Cyclic AMP/Protein Kinase A Pathways in Cryptococcus neoformans

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Maureen J. Donlin ◽  
Rajendra Upadhya ◽  
Kimberly J. Gerik ◽  
Woei Lam ◽  
Laura G. VanArendonk ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Cryptococcus Neoformans ◽  
Signaling Pathway ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Content Type ◽  
Kinase A

ABSTRACTCryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely,PKC1,BCK1,MKK2, andMPK1results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions ofBCK1,MKK2, andMPK1compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis.IMPORTANCECryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.

scholarly journals The use of FTIR spectroscopy to monitor modifications in plant cell wall architecture caused by cellulose biosynthesis inhibitors

2011 ◽  
Vol 6 (8) ◽  
pp. 1104-1110 ◽  
Author(s):  
Ana Alonso-Simón ◽  
Penélope García-Angulo ◽  
Hugo Mélida ◽  
Antonio Encina ◽  
Jesús M. Álvarez ◽  
...  
Keyword(s):  
Cell Wall ◽  
Ftir Spectroscopy ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Cellulose Biosynthesis ◽  
Biosynthesis Inhibitors ◽  
Cell Wall Architecture

scholarly journals Aspergillus fumigatus RasA Regulates Asexual Development and Cell Wall Integrity

2008 ◽  
Vol 7 (9) ◽  
pp. 1530-1539 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Kevin K. Fuller ◽  
Timothy J. Stephens ◽  
W. Clark Bacon ◽  
David S. Askew ◽  
...  
Keyword(s):  
Cell Wall ◽  
Hyphal Growth ◽  
Cell Wall Integrity ◽  
Signaling Cascades ◽  
Asexual Development ◽  
Wild Type ◽  
Calcofluor White ◽  
Ras Family ◽  
Type Gene ◽  
Increased Susceptibility

ABSTRACT The Ras family of proteins is a large group of monomeric GTPases. Members of the fungal Ras family act as molecular switches that transduce signals from the outside of the cell to signaling cascades inside the cell. A. fumigatus RasA is 94% identical to the essential RasA gene of Aspergillus nidulans and is the Ras family member sharing the highest identity to Ras homologs studied in many other fungi. In this study, we report that rasA is not essential in A. fumigatus, but its absence is associated with slowed germination and a severe defect in radial growth. The ΔrasA hyphae were more than two times the diameter of wild-type hyphae, and they displayed repeated changes in the axis of polarity during hyphal growth. The deformed hyphae accumulated numerous nuclei within each hyphal compartment. The ΔrasA mutant conidiated poorly, but this phenotype could be ameliorated by growth on osmotically stabilized media. The ΔrasA mutant also showed increased susceptibility to cell wall stressors, stained more intensely with calcofluor white, and was refractory to lysing enzymes used to make protoplasts, suggesting an alteration of the cell wall. All phenotypes associated with deletion of rasA could be corrected by reinsertion of the wild-type gene. These data demonstrate a crucial role for RasA in both hyphal growth and asexual development in A. fumigatus and provide evidence that RasA function is linked to cell wall integrity.

scholarly journals The Aspergillus fumigatus P-Type Golgi Apparatus Ca2+/Mn2+ ATPase PmrA Is Involved in Cation Homeostasis and Cell Wall Integrity but Is Not Essential for Pathogenesis

2010 ◽  
Vol 9 (3) ◽  
pp. 472-476 ◽  
Author(s):  
Nadthanan Pinchai ◽  
Praveen Rao Juvvadi ◽  
Jarrod R. Fortwendel ◽  
B. Zachary Perfect ◽  
Luise E. Rogg ◽  
...  
Keyword(s):  
Cell Wall ◽  
Golgi Apparatus ◽  
Aspergillus Fumigatus ◽  
Cell Wall Integrity ◽  
Content Type ◽  
Growth Defects ◽  
Chitin Content ◽  
Cation Homeostasis ◽  
P Type ◽  
Calcineurin Pathway

ABSTRACT The Aspergillus fumigatus ΔpmrA (Golgi apparatus Ca2+/Mn2+ P-type ATPase) strain has osmotically suppressible basal growth defects and cationic tolerance associated with increased expression of calcineurin pathway genes. Despite increased β-glucan and chitin content, it is hypersensitive to cell wall inhibitors but remains virulent, suggesting a role for PmrA in cation homeostasis and cell wall integrity.

scholarly journals Arabidopsis ERF4 and MYB52 Transcription Factors Play Antagonistic Roles in Regulating Homogalacturonan De-methylesterification in Seed Coat Mucilage

2020 ◽  
Author(s):  
Anming Ding ◽  
Xianfeng Tang ◽  
Linhe Han ◽  
Jianlu Sun ◽  
Angyan Ren ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factors ◽  
Seed Coat ◽  
Pectin Methylesterase ◽  
Wild Type ◽  
Expression Studies ◽  
Gene Expression Studies ◽  
Transcriptional Complex ◽  
Seed Coat Mucilage ◽  
Seed Mucilage

ABSTRACTThe Arabidopsis (Arabidopsis thaliana) seed coat mucilage is a specialized cell wall with pectin as its major component. Pectin is synthesized in the Golgi apparatus with homogalacturonan fully methylesterified, but it must undergo de-methylesterification by pectin methylesterase (PME) after being secreted into the cell wall. This reaction is critical for pectin maturation, but the mechanisms of its transcriptional regulation remain largely unknown. Here, we show that the Arabidopsis ERF4 transcription factor positively regulates pectin de-methylesterification during seed development and directly suppresses the expression of PME INHIBITOR13 (PMEI13), 14, 15 and SUBTILISIN-LIKE SERINE PROTEASE 1.7 (SBT1.7). The erf4 mutant seeds showed repartitioning of mucilage between soluble and adherent layers as a result of decreased PME activity and increased degree of pectin methylesterification. ERF4 physically associates with and antagonizes MYB52 in activating PMEI6, 14 and SBT1.7 and MYB52 also antagonizes ERF4 activity in the regulation of downstream targets. Gene expression studies revealed that ERF4 and MYB52 have opposite effects on pectin de-methylesterification. Genetic analysis indicated that the erf4-2 myb52 double mutant seeds show mucilage phenotype similar to wild-type. Taken together, this study demonstrates that ERF4 and MYB52 antagonize each other’s activity to maintain the appropriate degree of pectin methylesterification, expanding our understanding of how pectin de-methylesterification is fine-tuned by the ERF4-MYB52 transcriptional complex in the seed mucilage.One-sentence summaryArabidopsis ERF4 and MYB52 transcription factors interact and play antagonistic roles in regulating homogalacturonan de-methylesterification related genes in the seed coat mucilage.

scholarly journals Cellulose biosynthesis inhibition reduces cell cycle activity in a nitrate reductase- and cytokinin-dependent manner

2018 ◽  
Author(s):  
Nora Gigli-Bisceglia ◽  
Timo Engelsdorf ◽  
Miroslav Strnad ◽  
Lauri Vaahtera ◽  
Amel Jamoune ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Wall ◽  
Salicylic Acid ◽  
Jasmonic Acid ◽  
Cell Wall Integrity ◽  
Cell Cycle Gene ◽  
List Type ◽  
Cellulose Biosynthesis ◽  
Cell Cycle Gene Expression

SummaryDuring growth, development and defense, cell wall integrity needs to be coordinated with cell cycle activity. In Saccharomyces cerevisiae, coordination is mediated by the cell wall integrity maintenance mechanism. In plants, little is known how coordination is achieved.Here we investigated coordination between plant cell wall and cell cycle activity in Arabidopsis thaliana seedlings by studying the impact of cell wall damage (CWD, caused by cellulose biosynthesis inhibition) on cell cycle gene expression, growth, phytohormone (jasmonic acid, salicylic acid, cytokinins) and lignin accumulation.We found root growth and cell cycle gene expression are reduced by CWD in an osmo-sensitive manner. trans-zeatin application suppressed the CWD effect on gene expression. Quantification of cytokinins revealed CWD-induced, osmo-sensitive changes in several cytokinins. Expression of CYTOKININ OXIDASE2/DEHYDROGENASE (CKX2) and CKX3, encoding cytokinin-degrading enzymes, was elevated in CWD-exposed seedlings. Genetic studies implicated NITRATE REDUCTASE1/2 (NIA1/2) in the response to CWD. In nia1/2 seedlings CWD induced neither expression of CKX2/3 and cell cycle genes nor accumulation of jasmonic acid, salicylic acid and lignin.This suggests that CWD causes increased CKX2/3 expression through a NIA1/2-mediated process. Increased CKX expression seems to cause changes in cytokinin levels, leading to reduced cell cycle gene expression.

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