Disease relevance of Genes, Fungal

• The analysis of wife-husband joint ABO blood group distribution in couples with habitual abortion showed an excess of A incompatible mating type and a defect of B incompatible type as compared with expected proportions assuming random mating [1].
• Helicase-like transcription factor (HLTF), a member of the SWI/SNF (mating type switching/sucrose nonfermenting) chromatin-remodeling complex, is recently found to be inactivated by promoter hypermethylation in human colorectal cancer [2].
• Among 234 terminal chickens from the initial four mating types the incidence of metastasis associated with B5/B5 Leghorns (66%) was substantially higher than for B24/B24 New Hampshires (12%) and B5/B24 progeny of reciprocal Leghorn-New Hampshire crosses (19 and 24%) [3].
• To the best of our knowledge, this is the first report of disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of C. neoformans var. grubii, serotype A, possessing mating type allele A alpha; the strain is probably a hybrid [4].
• Amniocentesis and subsequent tests are reported on a fetus conceived of a rare mating type: its mother has an intermediate level of beta hexosaminidase A (HEX A), characteristic of carriers of Tay-Sachs disease (TSD), while the father suffers from an adult-onset GM2 gangliosidosis (AOG) with severe HEX A deficiency [5].

High impact information on Genes, Fungal

• Other Htz1-activated genes flank the silent HMR mating-type locus [6].
• Yeast SIR2 is a NAD+-dependent histone deacetylase required for heterochromatic silencing at telomeres, rDNA, and mating-type loci [7].
• Using a yeast heat shock gene flanked by mating-type silencers as a model system, we find that repressive, SIR-generated heterochromatin is permissive to the constitutive binding of an activator, HSF, and two components of the preinitiation complex (PIC), TBP and Pol II [8].
• Here, we show that Sir3p is released from telomeres in response to DNA double-strand breaks (DSBs), binds to DSBs, and mediates their repair, independent of cell mating type [9].
• We have now found that the clr4 gene, which is essential for silencing of centromeres and the mating-type loci in Schizosaccharomyces pombe, encodes a protein with high homology to the product of Su(var)3-9, a gene affecting PEV in Drosophila [10].

Biological context of Genes, Fungal

• Thus, while it is clear that IME1 is a necessary positive regulator of meiosis, responding both to mating type and nutritional conditions, it is not clear if it is sufficient [11].
• This human homeobox protein was shown to bind the same DNA sequence as the homeobox domains of the yeast mating type proteins and Drosophila homeotic protein, suggesting that homeobox proteins may have closely related DNA binding characteristics [12].
• Cell division yields a mother cell, which is competent to transcribe the HO gene and switch mating type, and a daughter cell, which is not [13].
• A portion of the conserved protein domain present in ftz and several homoeotic genes resembles the DNA-binding region of prokaryotic DNA-binding proteins, and is also similar to products of the yeast mating-type locus [14].
• Here, we show that distinct site-specific histone H3 methylation patterns define euchromatic and heterochromatic chromosomal domains within a 47-kilobase region of the mating-type locus in fission yeast [15].

Anatomical context of Genes, Fungal

• This regulation is vital for mother-cell specificity since constitutive transcription of SWI5 causes daughter cells to switch their mating types [16].
• In yeast Saccharomyces cerevisiae, Ash1p, a protein determinant for mating-type switching, is segregated within the daughter cell nucleus to establish asymmetry of HO expression [17].
• We further show that gametes of a single mating type can be induced to undergo all three mating responses when presented with exogenous dibutyryl-cAMP (db-cAMP) [18].
• Cell wall lysis, a necessary prelude to fusion, is shown to require flagellar agglutination between competent gametes; glutaraldehyde-fixed gametes ("corpses") of one mating type will elicit both agglutination and cell wall lysis in the opposite mating type, whereas nonagglutinating impotent (imp) mutant strains are without effect [19].
• The effects of glucose repression are independent of cellular mating type and mitochondrial genotype, and take place at least in part after zygotes are formed [20].

Associations of Genes, Fungal with chemical compounds

• Electrophoretic analysis on SDS polyacrylamide gel revealed no significant difference in polypeptide patterns of the particles from the two complementary mating types [21].
• We obtained transgenic potato plants expressing a fungal gene encoding glucose oxidase, which generates H2O2 when glucose is oxidized [22].
• Activity is in some cases dependent upon the particular A alpha mating type of the recipient [23].
• Conjugation in Blepharisma japonicum is induced by interaction between complementary mating-types I and II, which excrete blepharmone (gamone 1) and blepharismone (gamone 2), respectively [24].
• By introducing a thiamine repressible promoter upstream of the mat1 locus, we can force transcription through the imprinted region, erasing the imprint and inhibiting further mating-type switching, in a reversible manner [25].

Gene context of Genes, Fungal

• Both positive and negative regulators of HO transcription are required for mother-cell-specific mating-type switching in yeast [26].
• The SIR2, SIR3, and SIR4 proteins are required for silencing of transcription at the silent mating type loci and at telomeres in yeast [27].
• Deletion and overexpression of ASH1 cause reciprocal cell fate transformations: im ash1delta strains, daughters switch mating type as efficiently as mothers [13].
• SIR1, one of several genes required for repression of yeast silent mating type loci, has a unique role in repression of the HML alpha locus [28].
• Previous studies have demonstrated a direct role for RAP1 in silencing at HM mating-type loci and telomeres [29].

Analytical, diagnostic and therapeutic context of Genes, Fungal

• Consistent with the idea that San1 participates as an accessory factor to regulate silent chromatin, including the silent mating-type loci, microarray analysis defined a small but statistically significant role for San1 in transcription of several mating pheromone-responsive genes [30].
• Under the hypothesis that the conA receptor may be a mating type receptor, we have used this ligand-induced differential cytoskeletal association, in conjunction with electrophoresis and Western blotting, to identify a glycoprotein with an apparent molecular weight (MW) of 23,000 D which may be a mating type receptor [31].
• PCR analysis with primers specific for genes in the MATa or MATalpha mating-type loci revealed that serotype AD strains are heterozygous for the mating-type locus [32].
• In tetrad dissection of prototrophic diploids that were obtained by rare mating of hml alpha-1 mutants with a heterothallic strain having the MATa ho HMRa HMLa genotype, many mating-deficient haploid segregants were found, while alpha mating-type segregants were observed in a similar diploid using an hml alpha-2 mutant [33].
• Using cDNA array profiling, we compared the levels of expression of fungal genes corresponding to approximately 1,200 expressed sequenced tags in the ectomycorrhizal root tips (ECM) and the connected extraradical mycelium (EM) for the Paxillus involutus-Betula pendula ectomycorrhizal association grown on peat in a microcosm system [34].

References