scholarly journals Characterization of Neurospora crassa cyclic AMP phosphodiesterase activated by calmodulin

1985 ◽  
Vol 232 (2) ◽  
pp. 425-430 ◽  
Author(s):  
M T Téllez-Iñón ◽  
R M Ulloa ◽  
G C Glikin ◽  
H N Torres
Keyword(s):  
Cyclic Amp ◽  
Neurospora Crassa ◽  
Cyclic Nucleotide ◽  
Neuroleptic Drugs ◽  
Wild Type ◽  
Cyclic Amp Phosphodiesterase ◽  
Aerial Hyphae

Activation of cyclic AMP phosphodiesterase I by brain or Neurospora calmodulin was studied. The stimulation required micromolar concentrations of Ca2+, and it was observed at cyclic AMP concentrations between 0.1 and 500 microM. Activation was blocked by EDTA and some neuroleptic drugs such as chlorpromazine and fluphenazine. These drugs inhibit the elongation of N. crassa wild-type aerial hyphae. These results reinforce the evidence towards the recognition of Ca2+-calmodulin as one of the systems controlling cyclic nucleotide concentrations in Neurospora.

scholarly journals Mutational Activation of a Gαi Causes Uncontrolled Proliferation of Aerial Hyphae and Increased Sensitivity to Heat and Oxidative Stress in Neurospora crassa

Genetics ◽  
1999 ◽  
Vol 151 (1) ◽  
pp. 107-117
Author(s):  
Qi Yang ◽  
Katherine A Borkovich
Keyword(s):  
Signal Transduction ◽  
Neurospora Crassa ◽  
Signal Transduction Pathway ◽  
Sexual Cycle ◽  
Intracellular Camp ◽  
Wild Type ◽  
Independent Functions ◽  
Aerial Hyphae ◽  
Mutational Activation ◽  
Camp Levels

Abstract Heterotrimeric G proteins, consisting of α, β, and γ subunits, transduce environmental signals through coupling to plasma membrane-localized receptors. We previously reported that the filamentous fungus Neurospora crassa possesses a Gα protein, GNA-1, that is a member of the Gαi superfamily. Deletion of gna-1 leads to defects in apical extension, differentiation of asexual spores, sensitivity to hyperosmotic media, and female fertility. In addition, Δgna-1 strains have lower intracellular cAMP levels under conditions that promote morphological abnormalities. To further define the function of GNA-1 in signal transduction in N. crassa, we examined properties of strains with mutationally activated gna-1 alleles (R178C or Q204L) as the only source of GNA-1 protein. These mutations are predicted to inhibit the GTPase activity of GNA-1 and lead to constitutive signaling. In the sexual cycle, gna-1R178C and gna-1Q204L strains are female-fertile, but produce fewer and larger perithecia than wild type. During asexual development, gna-1R178C and gna-1Q204L strains elaborate abundant, long aerial hyphae, produce less conidia, and possess lower levels of carotenoid pigments in comparison to wild-type controls. Furthermore, gna-1R178C and gna-1Q204L strains are more sensitive to heat shock and exposure to hydrogen peroxide than wild-type strains, while Δgna-1 mutants are more resistant. In contrast to Δgna-1 mutants, gna-1R178C and gna-1Q204L strains have higher steady-state levels of cAMP than wild type. The results suggest that GNA-1 possesses several Gβγ-independent functions in N. crassa. We propose that GNA-1 mediates signal transduction pathway(s) that regulate aerial hyphae development and sensitivity to heat and oxidative stresses, possibly through modulation of cAMP levels.

scholarly journals The ham-2 Locus, Encoding a Putative Transmembrane Protein, Is Required for Hyphal Fusion in Neurospora crassa

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 169-180
Author(s):  
Qijun Xiang ◽  
Carolyn Rasmussen ◽  
N Louise Glass
Keyword(s):  
Neurospora Crassa ◽  
Somatic Cell ◽  
Molecular Mechanism ◽  
Cell Fusion ◽  
Deletion Mutant ◽  
Transmembrane Protein ◽  
Wild Type ◽  
Vegetative Incompatibility ◽  
Hyphal Fusion ◽  
Aerial Hyphae

Abstract Somatic cell fusion is common during organogenesis in multicellular eukaryotes, although the molecular mechanism of cell fusion is poorly understood. In filamentous fungi, somatic cell fusion occurs during vegetative growth. Filamentous fungi grow as multinucleate hyphal tubes that undergo frequent hyphal fusion (anastomosis) during colony expansion, resulting in the formation of a hyphal network. The molecular mechanism of the hyphal fusion process and the role of networked hyphae in the growth and development of these organisms are unexplored questions. We use the filamentous fungus Neurospora crassa as a model to study the molecular mechanism of hyphal fusion. In this study, we identified a deletion mutant that was restricted in its ability to undergo both self-hyphal fusion and fusion with a different individual to form a heterokaryon. This deletion mutant displayed pleiotropic defects, including shortened aerial hyphae, altered conidiation pattern, female sterility, slow growth rate, lack of hyphal fusion, and suppression of vegetative incompatibility. Complementation with a single open reading frame (ORF) within the deletion region in this mutant restored near wild-type growth rates, female fertility, aerial hyphae formation, and hyphal fusion, but not vegetative incompatibility and wild-type conidiation pattern. This ORF, which we named ham-2 (for hyphal anastomosis), encodes a putative transmembrane protein that is highly conserved, but of unknown function among eukaryotes.

Cloning and characterization of the low-affinity cyclic AMP phosphodiesterase gene of Saccharomyces cerevisiae

1987 ◽  
Vol 7 (10) ◽  
pp. 3629-3636
Author(s):  
J Nikawa ◽  
P Sass ◽  
M Wigler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cyclic Amp ◽  
Copy Number ◽  
Growth Arrest ◽  
Yeast Cells ◽  
Phosphodiesterase Activity ◽  
Camp Phosphodiesterase ◽  
High Affinity ◽  
Cyclic Amp Phosphodiesterase

Saccharomyces cerevisiae contains two genes which encode cyclic AMP (cAMP) phosphodiesterase. We previously isolated and characterized PDE2, which encodes a high-affinity cAMP phosphodiesterase. We have now isolated the PDE1 gene of S. cerevisiae, which encodes a low-affinity cAMP phosphodiesterase. These two genes represent highly divergent branches in the evolution of phosphodiesterases. High-copy-number plasmids containing either PDE1 or PDE2 can reverse the growth arrest defects of yeast cells carrying the RAS2(Val-19) mutation. PDE1 and PDE2 appear to account for the aggregate cAMP phosphodiesterase activity of S. cerevisiae. Disruption of both PDE genes results in a phenotype which resembles that induced by the RAS2(Val-19) mutation. pde1- pde2- ras1- ras2- cells are viable.

scholarly journals Deficient cyclic adenosine 3',5'-monophosphate control in mutants of two genes of Neurospora crassa.

1981 ◽  
Vol 1 (1) ◽  
pp. 1-8 ◽  
Author(s):  
M L Pall ◽  
J M Trevillyan ◽  
N Hinman
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Neurospora Crassa ◽  
Alternative Oxidase ◽  
Oscillatory Behavior ◽  
Wild Type ◽  
Glucose Transport System ◽  
Regulated Functions

Strains of Neurospora crassa mutant in either of two genes, Crisp-1 (cr1) and Frost (fr), showed no increase of cyclic adenosine 3',5'-monophosphate (cyclic AMP) levels when subjected to several treatments which produce large increases of cyclic AMP in wild-type Neurospora. Evidently, the previously reported deficiencies of adenylate cyclase in these mutants were sufficient to block the normal increases. This fact suggests that both mutants could be used to help determine which control phenomena involve cyclic AMP and to interrupt the control of established cyclic AMP-regulated functions. Earlier studies had suggested an interdependence of the cyclic AMP level and the electric potential difference across the plasma membrane of Neurospora. Present experiments, therefore, employed several strains with the cr1 mutation to test for possible roles of cyclic AMP in recovery and oscillatory behavior of the Neurospora membrane potential. The results showed all such phenomena to be normal in the adenylate cyclase-defective strains, which demonstrates that variations of cyclic AMP are not obligatorily involved in the apparent control processes. Evidence is also presented that the induction of both glucose transport system II and the alternative oxidase do not require elevated cyclic AMP levels.

Growth of S49 wild type cells in 3 nM epinephrine increases cyclic AMP phosphodiesterase activity

Life Sciences ◽  
1994 ◽  
Vol 54 (13) ◽  
pp. 863-875 ◽  
Author(s):  
Mark D. Richardson ◽  
Thomas J. Goka ◽  
Roger Barber ◽  
R.W. Butcher
Keyword(s):  
Cyclic Amp ◽  
Phosphodiesterase Activity ◽  
Wild Type ◽  
Cyclic Amp Phosphodiesterase
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