Disease relevance of EXG1

• Yeast exo-beta-1,3-glucanase gene (EXG1) was expressed in Escherichia coli and the recombinant enzyme (Exg1p) was characterized [1].

High impact information on EXG1

• Overexpression of Exg1 (major exoglucanase), or loss of Kex2 (endoprotease involved in Exg1 processing), rescued growth at high temperature [2].
• By N-terminal sequencing, three of these proteins were identified as the known proteins beta-exoglucanase 1 (Exg1p), beta-endoglucanase (Bgl2p), and chitinase (Cts1p) [3].
• 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) [4].
• We isolated two genes for extracellular beta-glucosidase, BGL1 and BGL2, from the genomic library of the yeast Saccharomycopsis fibuligera [5].
• This result is consistent with the observation that the S. cerevisiae transformant carrying BGL1 fermented cellobiose to ethanol but the transformant carrying BGL2 did not [5].

Biological context of EXG1

• EXG1 and PBS2 were isolated as genes that, when expressed from multicopy plasmids, led to a dominant killer toxin-resistant phenotype [6].
• Disruption of PTC1/CWH47 and overexpression of PBS2 gave rise to similar beta-glucan related phenotypes, with higher levels of EXG1 transcription, increased exo-beta-glucanase activity, reduced beta 1,6-glucan levels, and resistance to killer toxin [6].
• 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 [7].
• Meiotic tetrad analyses further localized the EXG1 gene 6.1 centimorgans centromere-proximal to CDC25 on the right arm of chromosome XII [8].
• Only one copy of the EXG1 gene per genome was found in several strains tested by Southern analysis [9].

Anatomical context of EXG1

• Analysis of genes involved in yeast cell wall beta-glucan assembly has led to the isolation of EXG1, PBS2 and PTC1 [6].

Associations of EXG1 with chemical compounds

• These results suggest that Ptc1p/Cwh47p and Pbs2p play opposing regulatory roles in cell wall glucan assembly, and that this is effected in part by modulating Exg1p activity [6].
• Since fluorescein di(beta-D-glucopyranoside) is a fluorogenic substrate detectable and quantifiable by flow cytometry, it was used for testing the ability of the EXG1 gene product of Saccharomyces cerevisiae and its homologous gene in Candida albicans to function as reporter genes [10].
• An extracellular exo-beta-(1,3)-glucanase (designated EXG1) was purified to apparent homogeneity from Pichia pastoris X-33 cultures by ammonium sulfate fractionation, ion-exchange chromatography, and gel filtration [11].
• S. cerevisiae secreting the recombinant S. fibuligera BGL1 enzyme sustained growth aerobically and anaerobically, in minimal medium containing 5g L(-1) cellobiose at 0.23 h(-1) (compared to 0.29 h(-1) on glucose) and 0.18 h(-1) (compared to 0.25 h(-1) on glucose), respectively [12].

Regulatory relationships of EXG1

• Various alcohols and terpenes were enhanced in the aroma profiles of wines produced by inoculation with the exoglucanase over-expressing yeasts, though the transformant strain carrying EXG1 under the control of the actin promoter yielded higher levels of free volatiles in wine [13].

Other interactions of EXG1

• The production of exoglucanase activity by two wine yeast strain transformants in which the expression of EXG1 was driven by either the S. cerevisiae actin or EXG1 gene promoters has been monitored in culture medium and in grape must during the fermentation process [13].

Analytical, diagnostic and therapeutic context of EXG1

• The molecular cloning of 1,3-beta-glucanase-encoding genes from different yeast species was achieved by screening genomic libraries with DNA probes obtained by PCR-amplification using oligonucleotides designed according to conserved regions in the EXG1, EXG2 and SSG1 genes from Saccharomyces cerevisiae [14].
• Bioreactor cultures were operated at two dilution rates (0.14 and 0.03 h(-1)) to investigate the effect of other process parameters on EXG1 expression [15].
• The recombinant CBHI gave two bands of different molecular mass (110 and 90 kDa) and the recombinant BGL1 gave one band (180 kDa) by SDS-PAGE [16].

References