High impact information on PHO3

• Nuclease hypersensitive regions with adjacent positioned nucleosomes mark the gene boundaries of the PHO5/PHO3 locus in yeast [1].
• An active genomic copy of PHO5 was able to block expression of PHO3 from a high-copy-number plasmid, showing that some trans-acting product of PHO5 is involved [2].
• Reciprocal regulation of the tandemly duplicated PHO5/PHO3 gene cluster within the acid phosphatase multigene family of Saccharomyces cerevisiae [2].
• After transfer from repressing to inducing medium, the promoter activity of both THI2 and THI3 increased in parallel with that of PHO3, one of THI genes [3].
• Doubly heterozygous diploids, pho3 PHO82c PHO4+/pho3 pho82+ pho4, produce variable amounts of repressible acid phosphatase under repressive conditions depending on the combination of PHO82c and pho4 alleles [4].

Biological context of PHO3

• Subcloning of partial Sau3A digests and functional in vivo analysis by transformation together with DNA sequence analysis showed that the two genes are oriented in the order (5') PHO5 , PHO3 (3') [5].
• Increasing lengths of 5'-flanking sequences of the PHO5 gene were placed in front of the TATA-box of constitutively expressed acid phosphatase gene (PHO3) [6].
• Sl-nuclease protection experiments revealed that the PHO5 5'-flanking sequences, placed in front of PHO3, did not change the PHO3 transcription initiation site/s [6].
• Our data indicate that the improved secretion is caused by mitotic intrachromosomal recombination between the PHO5-11 allele and the homologous tandemly repeated PHO3 sequences, resulting in the restoration of glycosylation sites in PHO5-11 [7].
• The pho3 mutant cells of S. cerevisiae in contrast to the parent cells have markedly reduced activity of the uptake of [14C]thiamin phosphates, suggesting that thiamin repressible acid phosphatase plays a role in the hydrolysis of thiamin phosphates in the periplasmic space prior to the uptake of their thiamin moieties by S. cerevisiae [8].

Associations of PHO3 with chemical compounds

• Genetic analyses using plasmids carrying the genes, PHO5 and PHO3, that code for repressible APase and constitutive APase, respectively, showed that linolenic acid induced the formation of repressible APase [9].
• A possible role for acid phosphatase with thiamin-binding activity encoded by PHO3 in yeast [8].
• Using a deletion strain, we further demonstrate that the main secretory acid phosphatase Pho5p is not essential for intact phytate-degrading capacity and growth without Pi, neither is Pho3p [10].

Other interactions of PHO3

• It was shown that the constitutive acid phosphatase (PHO3 gene product) is mainly transported to the cell surface by a lower density population of vesicles, while the repressible acid phosphatase (a heteromer encoded by PHO5, PHO10, and PHO11 genes) by a vesicle population of higher density [11].

Analytical, diagnostic and therapeutic context of PHO3

• The transcription levels of PHO3 were determined by northern blot analysis, under repressed (high Pi) and derepressed (low Pi) conditions which was paralleled by an increase in extra-cellular acid phosphatase activity [6].

References