scholarly journals Intracellular Siderophores Are Essential for Ascomycete Sexual Development in Heterothallic Cochliobolus heterostrophus and Homothallic Gibberella zeae

2007 ◽  
Vol 6 (8) ◽  
pp. 1339-1353 ◽  
Author(s):  
Shinichi Oide ◽  
Stuart B. Krasnoff ◽  
Donna M. Gibson ◽  
B. Gillian Turgeon
Keyword(s):  
Sexual Development ◽  
Gibberella Zeae ◽  
Cochliobolus Heterostrophus ◽  
Fungal Development ◽  
Exogenous Application ◽  
Functional Conservation ◽  
Peptide Synthetase ◽  
Ascospore Development ◽  
Mutant Strains ◽  
Biochemical Analyses

ABSTRACT Connections between fungal development and secondary metabolism have been reported previously, but as yet, no comprehensive analysis of a family of secondary metabolites and their possible role in fungal development has been reported. In the present study, mutant strains of the heterothallic ascomycete Cochliobolus heterostrophus, each lacking one of 12 genes (NPS1 to NPS12) encoding a nonribosomal peptide synthetase (NRPS), were examined for a role in sexual development. One type of strain (Δnps2) was defective in ascus/ascospore development in homozygous Δnps2 crosses. Homozygous crosses of the remaining 11 Δnps strains showed wild-type (WT) fertility. Phylogenetic, expression, and biochemical analyses demonstrated that the NRPS encoded by NPS2 is responsible for the biosynthesis of ferricrocin, the intracellular siderophore of C. heterostrophus. Functional conservation of NPS2 in both heterothallic C. heterostrophus and the unrelated homothallic ascomycete Gibberella zeae was demonstrated. G. zeae Δnps2 strains are concomitantly defective in intracellular siderophore (ferricrocin) biosynthesis and sexual development. Exogenous application of iron partially restored fertility to C. heterostrophus and G. zeae Δnps2 strains, demonstrating that abnormal sexual development of Δnps2 strains is at least partly due to their iron deficiency. Exogenous application of the natural siderophore ferricrocin to C. heterostrophus and G. zeae Δnps2 strains restored WT fertility. NPS1, a G. zeae NPS gene that groups phylogenetically with NPS2, does not play a role in sexual development. Overall, these data demonstrate that iron and intracellular siderophores are essential for successful sexual development of the heterothallic ascomycete C. heterostrophus and the homothallic ascomycete G. zeae.

scholarly journals Disassembly activity of actin-depolymerizing factor (ADF) is associated with distinct cellular processes in apicomplexan parasites

2015 ◽  
Vol 26 (17) ◽  
pp. 3001-3012 ◽  
Author(s):  
Silvia Haase ◽  
Dennis Zimmermann ◽  
Maya A. Olshina ◽  
Mark Wilkinson ◽  
Fabio Fisher ◽  
...  
Keyword(s):  
Parasite Development ◽  
Actin Depolymerizing Factor ◽  
Phenotypic Effect ◽  
Basic Residue ◽  
Human Malaria Parasite ◽  
Apicomplexan Parasites ◽  
Functional Conservation ◽  
Cellular Processes ◽  
Organelle Segregation ◽  
Biochemical Analyses

Proteins of the actin-depolymerizing factor (ADF)/cofilin family have been shown to be crucial for the motility and survival of apicomplexan parasites. However, the mechanisms by which ADF proteins fulfill their function remain poorly understood. In this study, we investigate the comparative activities of ADF proteins from Toxoplasma gondii and Plasmodium falciparum, the human malaria parasite, using a conditional T. gondii ADF-knockout line complemented with ADF variants from either species. We show that P. falciparum ADF1 can fully restore native TgADF activity, demonstrating functional conservation between parasites. Strikingly, mutation of a key basic residue (Lys-72), previously implicated in disassembly in PfADF1, had no detectable phenotypic effect on parasite growth, motility, or development. In contrast, organelle segregation was severely impaired when complementing with a TgADF mutant lacking the corresponding residue (Lys-68). Biochemical analyses of each ADF protein confirmed the reduced ability of lysine mutants to mediate actin depolymerization via filament disassembly although not severing, in contrast to previous reports. These data suggest that actin filament disassembly is essential for apicomplexan parasite development but not for motility, as well as pointing to genus-specific coevolution between ADF proteins and their native actin.

scholarly journals Nostophycin Biosynthesis Is Directed by a Hybrid Polyketide Synthase-Nonribosomal Peptide Synthetase in the Toxic Cyanobacterium Nostoc sp. Strain 152

2011 ◽  
Vol 77 (22) ◽  
pp. 8034-8040 ◽  
Author(s):  
David P. Fewer ◽  
Julia Österholm ◽  
Leo Rouhiainen ◽  
Jouni Jokela ◽  
Matti Wahlsten ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Polyketide Synthase ◽  
Catalytic Domain ◽  
Phylogenetic Analyses ◽  
Biosynthetic Gene Cluster ◽  
Nonribosomal Peptide Synthetase ◽  
Open Reading Frames ◽  
Nonribosomal Peptide ◽  
Peptide Synthetase ◽  
Biochemical Analyses

ABSTRACTCyanobacteria are a rich source of natural products with interesting pharmaceutical properties. Here, we report the identification, sequencing, annotation, and biochemical analysis of the nostophycin (npn) biosynthetic gene cluster. Thenpngene cluster spans 45.1 kb and consists of three open reading frames encoding a polyketide synthase, a mixed polyketide nonribosomal peptide synthetase, and a nonribosomal peptide synthetase. The genetic architecture and catalytic domain organization of the proteins are colinear in arrangement, with the putative order of the biosynthetic assembly of the cyclic heptapeptide. NpnB contains an embedded monooxygenase domain linking nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) catalytic domains and predicted here to hydroxylate the nostophycin during assembly. Expression of the adenylation domains and subsequent substrate specificity assays support the involvement of this cluster in nostophycin biosynthesis. Biochemical analyses suggest that the loading substrate of NpnA is likely to be a phenylpropanoic acid necessitating deletion of a carbon atom to explain the biosynthesis of nostophycin. Biosyntheses of nostophycin and microcystin resemble each other, but the phylogenetic analyses suggest that they are distantly related to one another.

scholarly journals Functional Analyses of Two Acetyl Coenzyme A Synthetases in the Ascomycete Gibberella zeae

2011 ◽  
Vol 10 (8) ◽  
pp. 1043-1052 ◽  
Author(s):  
Seunghoon Lee ◽  
Hokyoung Son ◽  
Jungkwan Lee ◽  
Kyunghun Min ◽  
Gyung Ja Choi ◽  
...  
Keyword(s):  
Sexual Development ◽  
Coenzyme A ◽  
Lipid Synthesis ◽  
Gibberella Zeae ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Content Type ◽  
Temporal Precision ◽  
Acetyl Coenzyme

ABSTRACTAcetyl coenzyme A (acetyl-CoA) is a crucial metabolite for energy metabolism and biosynthetic pathways and is produced in various cellular compartments with spatial and temporal precision. Our previous study on ATP citrate lyase (ACL) inGibberella zeaerevealed that ACL-dependent acetyl-CoA production is important for histone acetylation, especially in sexual development, but is not involved in lipid synthesis. In this study, we deleted additional acetyl-CoA synthetic genes, the acetyl-CoA synthetases (ACSgenesACS1andACS2), to identify alternative acetyl-CoA production mechanisms for ACL. TheACS1deletion resulted in a defect in sexual development that was mainly due to a reduction in 1-palmitoyl-2-oleoyl-3-linoleoyl-rac-glycerol production, which is required for perithecium development and maturation. Another ACS coding gene,ACS2, has accessorial functions forACS1and has compensatory functions forACLas a nuclear acetyl-CoA producer. This study showed that acetate is readily generated during the entire life cycle ofG. zeaeand has a pivotal role in fungal metabolism. Because ACSs are components of the pyruvate-acetaldehyde-acetate pathway, this fermentation process might have crucial roles in various physiological processes for filamentous fungi.

scholarly journals The L-Type Calcium Ion Channel Cch1 Affects Ascospore Discharge and Mycelial Growth in the Filamentous Fungus Gibberella zeae (Anamorph Fusarium graminearum)

2007 ◽  
Vol 7 (2) ◽  
pp. 415-424 ◽  
Author(s):  
Heather E. Hallen ◽  
Frances Trail
Keyword(s):  
Ion Channel ◽  
Calcium Ion ◽  
Mycelial Growth ◽  
Transcript Abundance ◽  
Gene Replacement ◽  
Gibberella Zeae ◽  
Transcriptional Analysis ◽  
Saprobic Fungi ◽  
Ascospore Discharge ◽  
Ascospore Development

ABSTRACT Cch1, a putative voltage-gated calcium ion channel, was investigated for its role in ascus development in Gibberella zeae. Gene replacement mutants of CCH1 were generated and found to have asci which did not forcibly discharge spores, although morphologically ascus and ascospore development in the majority of asci appeared normal. Additionally, mycelial growth was significantly slower, and sexual development was slightly delayed in the mutant; mutant mycelia showed a distinctive fluffy morphology, and no cirrhi were produced. Wheat infected with Δcch1 mutants developed symptoms comparable to wheat infected with the wild type; however, the mutants showed a reduced ability to protect the infected stalk from colonization by saprobic fungi. Transcriptional analysis of gene expression in mutants using the Affymetrix Fusarium microarray showed 2,449 genes with significant, twofold or greater, changes in transcript abundance across a developmental series. This work extends the role of CCH1 to forcible spore discharge in G. zeae and suggests that this channel has subtle effects on growth and development.

Creating and screening Cochliobolus heterostrophus non-ribosomal peptide synthetase mutants

2008 ◽  
Vol 112 (2) ◽  
pp. 200-206 ◽  
Author(s):  
B. Gillian Turgeon ◽  
Shinichi Oide ◽  
Kathryn Bushley
Keyword(s):  
Cochliobolus Heterostrophus ◽  
Peptide Synthetase

scholarly journals A Large Genomic Deletion in Gibberella zeae Causes a Defect in the Production of Two Polyketides but not in Sexual Development or Virulence

2006 ◽  
Vol 22 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Sun-Hee Lee ◽  
Hee-Kyoung Kim ◽  
Sae-Yeon Hong ◽  
Yin-Won Lee ◽  
Sung-Hwan Yun
Keyword(s):  
Sexual Development ◽  
Gibberella Zeae ◽  
Genomic Deletion ◽  
Large Genomic Deletion

scholarly journals Histidine Kinase Two-Component Response Regulator Proteins Regulate Reproductive Development, Virulence, and Stress Responses of the Fungal Cereal Pathogens Cochliobolus heterostrophus and Gibberella zeae

2010 ◽  
Vol 9 (12) ◽  
pp. 1867-1880 ◽  
Author(s):  
Shinichi Oide ◽  
Jinyuan Liu ◽  
Sung-Hwan Yun ◽  
Dongliang Wu ◽  
Alex Michev ◽  
...  
Keyword(s):  
Stress Responses ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Gibberella Zeae ◽  
Cochliobolus Heterostrophus ◽  
Wild Type ◽  
Content Type ◽  
Major Mechanism ◽  
Asexual Spore ◽  
Mutant Phenotypes

ABSTRACT Histidine kinase (HK) phosphorelay signaling is a major mechanism by which fungi sense their environment. The maize pathogen Cochliobolus heterostrophus has 21 HK genes, 4 candidate response regulator (RR) genes (SSK1, SKN7, RIM15, REC1), and 1 gene (HPT1) encoding a histidine phosphotransfer domain protein. Because most HKs are expected to signal through RRs, these were chosen for deletion. Except for pigment and slight growth alterations for rim15 mutants, no measurable altered phenotypes were detected in rim15 or rec1 mutants. Ssk1p is required for virulence and affects fertility and proper timing of sexual development of heterothallic C. heterostrophus. Pseudothecia from crosses involving ssk1 mutants ooze masses of single ascospores, and tetrads cannot be found. Wild-type pseudothecia do not ooze. Ssk1p represses asexual spore proliferation during the sexual phase, and lack of it dampens asexual spore proliferation during vegetative growth, compared to that of the wild type. ssk1 mutants are heavily pigmented. Mutants lacking Skn7p do not display any of the above phenotypes; however, both ssk1 and skn7 mutants are hypersensitive to oxidative and osmotic stresses and ssk1 skn7 mutants are more exaggerated in their spore-type balance phenotype and more sensitive to stress than single mutants. ssk1 mutant phenotypes largely overlap hog1 mutant phenotypes, and in both types of mutant, the Hog1 target gene, MST1, is not induced. ssk1 and hog1 mutants were examined in the homothallic cereal pathogen Gibberella zeae, and pathogenic and reproductive phases of development regulated by Ssk1 and Hog1 were found to mirror, but also vary from, those of C. heterostrophus.

scholarly journals Mid1, a Mechanosensitive Calcium Ion Channel, Affects Growth, Development, and Ascospore Discharge in the Filamentous Fungus Gibberella zeae

2011 ◽  
Vol 10 (6) ◽  
pp. 832-841 ◽  
Author(s):  
Brad Cavinder ◽  
Ahmed Hamam ◽  
Roger R. Lew ◽  
Frances Trail
Keyword(s):  
Ion Channel ◽  
Calcium Ion ◽  
Vegetative Growth ◽  
Gibberella Zeae ◽  
Calcium Flux ◽  
Wild Type ◽  
Content Type ◽  
Ascospore Discharge ◽  
Ascospore Development

ABSTRACT The role of Mid1, a stretch-activated ion channel capable of being permeated by calcium, in ascospore development and forcible discharge from asci was examined in the pathogenic fungus Gibberella zeae (anamorph Fusarium graminearum ). The Δ mid1 mutants exhibited a >12-fold reduction in ascospore discharge activity and produced predominately abnormal two-celled ascospores with constricted and fragile septae. The vegetative growth rate of the mutants was ∼50% of the wild-type rate, and production of macroconidia was >10-fold lower than in the wild type. To better understand the role of calcium flux, Δ mid1 Δ cch1 double mutants were also examined, as Cch1, an L-type calcium ion channel, is associated with Mid1 in Saccharomyces cerevisiae . The phenotype of the Δ mid1 Δ cch1 double mutants was similar to but more severe than the phenotype of the Δ mid1 mutants for all categories. Potential and current-voltage measurements were taken in the vegetative hyphae of the Δ mid1 and Δ cch1 mutants and the wild type, and the measurements for all three strains were remarkably similar, indicating that neither protein contributes significantly to the overall electrical properties of the plasma membrane. Pathogenicity of the Δ mid1 and Δ mid1 Δ cch1 mutants on the host (wheat) was not affected by the mutations. Exogenous calcium supplementation partially restored the ascospore discharge and vegetative growth defects for all mutants, but abnormal ascospores were still produced. These results extend the known roles of Mid1 to ascospore development and forcible discharge. However, Neurospora crassa Δ mid1 mutants were also examined and did not exhibit defects in ascospore development or in ascospore discharge. In comparison to ion channels in other ascomycetes, Mid1 shows remarkable adaptability of roles, particularly with regard to niche-specific adaptation.

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