High impact information on SPR1

• Mapping and sequence analysis also reveal that the SPR1 mitochondrial genome lacks three sectors of the wild-type molecule of 4.4, 1.7, and 0.5 kilobases [1].
• Absence of these sectors together with a rearranged gene order does not appear to affect the phenotype of SPR1, as colony morphology and growth rate on a number of different substrates are not detectably different from the wild type [1].
• Lack of phenotypic change suggests that mitochondrial gene expression has not been noticeably disrupted in SPR1 despite deletion of the consensus nonomer promoter upstream from the glutamic acid tRNA gene [1].
• The purified enzyme represented only 0.001% of the total 1,3-beta-glucanase activity, the remainder being due to an exo-1,3-beta-glucanase enzyme, and behaved as an acidic glycoprotein (pI 3.3) in isoelectric-focusing experiments [2].
• We have sequenced the SPR1 gene and found that it has extensive DNA and protein sequence homology to the S. cerevisiae EXG1 gene which encodes an exo-1,3-beta-glucanase expressed during vegetative growth (C. R. Vasquez de Aldana, J. Correa, P. San Segundo, A. Bueno, A. R. Nebrada, E. Mendez, and F. del Ray, Gene 97:173-182, 1991) [3].

Biological context of SPR1

• The YlEXG1 gene of Yarrowia lipolytica, encoding an exo-1, 3-beta-glucanase, was isolated by screening a genomic library with a DNA probe obtained by PCR amplification, using oligonucleotides designed according to conserved regions in the EXG1, EXG2 and SSG1 genes from Saccharomyces cerevisiae [4].
• Gene SSG1 encodes a 52 kDa polypeptide which is specifically synthesized during sporulation of diploids [5].
• The meiotic time course of SSG1 induction indicates that the gene is transcribed only in the late stages of the process, beginning at the time of meiosis I and reaching a maximum during spore formation [6].
• Nucleotide sequence of the exo-1,3-beta-glucanase-encoding gene, EXG1, of the yeast Saccharomyces cerevisiae [7].
• Finally, the SSG1 locus mapped on the right arm of chromosome XV, about 8.2 centimorgans to the centromere-proximal side of HIS3 [8].

Associations of SPR1 with chemical compounds

• We show that spr1 mutant cells do not hydrolyze p-nitrophenyl-beta-D-glucoside or laminarin in a whole-cell assay for exo-1,3-beta-glucanases [3].
• Saccharomyces cerevisiae S288C produced two laminarinases (1,3-beta-glucanases) which were separated by diethylaminoethyl-Sephadex column chromatography; one was an endo-1,3-beta-glucanase, and the other was an exo-1,3-beta-glucanase active not only on laminarin but also on pustulan (1,6-beta-glucan) and on p-nitrophenyl-beta-D-glucoside [9].
• Yeast cells of Candida albicans 1001 produced glucan-hydrolysing activity, most of which was due to an exo-1,3-beta-glucanase [10].

Other interactions of SPR1

• We conclude that SPR1, SPR2 and SPR3 transcription is modulated during sporulation, possibly in response to earlier events in the process [11].
• EXG1, EXG2 and SSG1 were localized to chromosomes XII, IV and XV, respectively, by hybridizing the cloned genes to Southern blots of chromosomes separated by pulsed-field gel electrophoresis, in conjunction with the rad52-1-dependent chromosome-loss mapping technique [8].
• Northern (RNA) analysis reveals a unique SSG1-specific transcript, 1.7 kb long, which can be detected only in sporulating diploids (MATa/MAT alpha) but does not appear in vegetatively growing cells or in nonsporulating diploids (MAT alpha/MAT alpha) when incubated under nitrogen starvation conditions [6].

References