Pleiotropic functions of the yeast Greatwall-family protein kinase Rim15p: a novel target for the control of alcoholic fermentation

This review was written in response to the author’s receipt of the JSBBA Award for Young Scientists in 2016.

Abbreviations: CDK, cyclin-dependent protein kinase; CE-TOFMS, capillary electrophoresis time-of-flight mass spectrometry; Dox, doxycycline; Ensa, α-endosulfine; G1P, glucose-1-phosphate; G6P, glucose-6-phosphate; Igo1/2p, Igo1p and Igo2p; K7, Kyokai no. 7; K701, Kyokai no. 701; Msn2/4p; Msn2p and Msn4p; PKA, protein kinase A; PP2A^B55δ, B55δ-bound protein phosphatase 2A; PP2A^Cdc55p, Cdc55p-bound protein phosphatase 2A; T6P, trehalose-6-phosphate; TORC1, target-of-rapamycin complex 1; UDPG, UDP-glucose.

Figures & data

Fig. 1. Comparison of growth and fermentation profiles.

Notes: Generally, the most vigorously fermenting cells occur in the stationary phase of the growth curve.

Fig. 2. The rim15^5055insA mutation found in K7 accounts for the high-fermenting phenotype.

Notes: (Left panel) The location of the rim15^5055insA mutation, a single adenine nucleotide insertion causing a reading frame shift near the downstream end of the ORF. PAS, CCHC, kinase, and REC represent a Per-Arnt-Sim domain, a CCHC-type zinc finger motif, protein kinase catalytic domains, and a receiver domain, respectively. (Right panel) The rim15^5055insA mutation (black bold line), as well as full deletion of RIM15 (gray line), strikingly increases the fermentation rate of the laboratory strain BY4743 in sake mash compared to that of the wild-type parent (black dashed line) [modified from Watanabe et al.¹³⁾].

Fig. 3. Known functions of the conserved Greatwall (Rim15p)-Ensa (Igo1/2p)-PP2A^B55δ (PP2A^Cdc55p) pathway in higher eukaryotes and S. cerevisiae.

Fig. 4. The Rim15p-mediated changes in UDPG and carbohydrate anabolic pathways result in inhibition of glycolysis and alcoholic fermentation [modified from Watanabe et al.³³⁾].

Fig. 5. The induction of UGP1 expression mediates the effect of Rim15p activation on alcoholic fermentation.

Notes: (Left panel) The UGP1 gene contains consensus Msn2/4p and Hsf1p-binding sites in its 5′-UTR sequence. While UGP1 is upregulated in the early stage of alcoholic fermentation (gray lines), the induction is clearly inhibited in strains with lesions in the gene encoding Rim15p (a laboratory strain harboring rim15Δ or a sake strain carrying the rim15^5055insA mutation; black lines). (Right panel) In the R1158 pUGP1::kan^R-tetO₇-TATA strain, addition of Dox decreases the expression of UGP1 and enhances alcoholic fermentation [modified from Watanabe et al.³³⁾].

Fig. 6. Effects of deletion of the RIM15 gene in industrial strains.

Notes: (Left panel) Deletion of RIM15 increases the fermentation rate and shortens the fermentation period in molasses fermentation using a strain derived from bioethanol yeast PE-2 [modified from Inai et al.⁴³⁾]. (Right panel) Deletion of RIM15 enhances sugar consumption in high-gravity wort fermentation using S. pastorianus strain Weihenstephan 34/70 [modified from Oomuro et al.⁴⁵⁾].

Watanabe D, Zhou Y, Hirata A, et al. Inhibitory role of Greatwall-like protein kinase Rim15p in alcoholic fermentation via upregulating the UDP-glucose synthesis pathway in Saccharomyces cerevisiae. Appl Environ Microbiol. 2016;82(1):340–351.10.1128/AEM.02977-15

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