Open AccessExpression of the glucose transporter HXT1 involves the Ser – Thr protein phosphatase S it4 in S accharomyces cerevisiae
Author(s) -
Souza Andréa A.,
Miranda Michel N.,
da Silva Suelene F.,
BozaquelMorais Bruno,
Masuda Claudio A.,
Ghislain Michel,
MonteroLomelí Mónica
Publication year - 2012
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/j.1567-1364.2012.00839.x
Subject(s) - biology , saccharomyces cerevisiae , yeast , phosphatase , strain (injury) , glucose transporter , casein , biochemistry , microbiology and biotechnology , enzyme , anatomy , insulin
We studied the effect of the loss of the Ser – Thr protein phosphatase Sit4, an important post‐translational regulator, on the steady‐state levels of the low‐affinity glucose transporter H xt1p and observed a delay in its appearance after high glucose induction, slow growth, and diminished glucose consumption. By analyzing the known essential pathway necessary to induce H xt1p, we observed a partial inhibition of casein kinase I activity. In both WT and sit4Δ strains, the transcript was induced with no significant difference at 15 min of glucose induction; however, after 45 min, a clear difference in the level of expression was observed being 45% higher in WT than in sit4Δ strain. As at early time of induction, the HXT1 transcript was present but not the protein in the sit4Δ strain we analyzed association of HXT1 with ribosomes, which revealed a significant difference in the association profile; in the mutant strain, the HXT1 transcript associated with a larger set of ribosomal fractions than it did in the WT strain, suggesting also a partial defect in protein synthesis. Overexpression of the translation initiation factor TIF2 / eIF 4A led to an increase in H xt1p abundance in the WT strain only. It was concluded that S it4p ensures that HXT1 transcript is efficiently transcribed and translated thus increasing protein levels of H xt1p when high glucose levels are present.