Disease relevance of HXT4

• Emulsan is a polyanionic heteropolysaccharide bioemulsifier produced by Acinetobacter calcoaceticus RAG-1 [1].

High impact information on HXT4

• One of the two DNA bending wedges on Nhp6A and the analogous phenylalanine wedge at the DNA exit site of HMGB1 domain A were found to be essential for promoting RAG1/2-RSS complex formation [2].
• In this study, we show that the HXT11 product, which allows glucose uptake in a glucose permease mutant (rag1) strain of Kluyveromyces lactis, is also involved in the pleiotropic drug resistance process [3].
• Transcription of the yeast HXT2 and HXT4 genes, which encode glucose transporters, is induced only by low levels of glucose [4].
• The HXT genes (HXT1 to HXT4) of the yeast Saccharomyces cerevisiae encode hexose transporters [5].
• The function of another new member of the HXT superfamily, HXT4 (previously identified by its ability to suppress the snf3 delta phenotype; L. Bisson, personal communication), was revealed in experiments that deleted all possible combinations of the five members of the glucose transporter gene family [6].

Biological context of HXT4

• The nucleotide sequence of the cloned gene indicated that the RAG1 product was a sugar transporter protein [7].
• The DDSE region from HXT4 was found to function as a UAS sequence rendering a UAS(gal)-less LacZ gene fused to the GAL1 promoter responsive to glucose induction [8].
• Using the HXT2 and HXT4 genes, we now present evidence for a functional link between Snf1p-dependent activation, recruitment of the SAGA complex, histone H3 removal, and H3 acetylation [9].
• These results also show that hyperosmotic stress interferes with the glucose-dependent transcriptional activation or derepression of HXT2 and HXT4 genes transcription in S. cerevisiae [10].
• RAD5 also contains a cysteine-rich sequence motif that resembles the corresponding sequences found in 11 other proteins, including those encoded by the DNA repair gene RAD18 and the RAG1 gene required for immunoglobin gene arrangement [11].

Associations of HXT4 with chemical compounds

• Functional characterization of the LGT1 gene product in S. cerevisiae revealed that it encodes a low-affinity transporter, able to mediate the uptake of glucose and fructose [12].
• As a consequence of the solubilization of the emulsan capsule, RAG-1 cells became more hydrophobic, as determined by adherence to hexadecane [1].

Physical interactions of HXT4

• Multicopy HXT4 increases both high and low affinity glucose transport in snf3 strains and increases low and high transport in wild-type strains [13].

Enzymatic interactions of HXT4

• Deletion of the FRT1 gene in a K. lactis strain already deleted for its RAG1 and HGT1 hexose transporter genes completely prevented uptake of and growth with fructose but not with glucose [14].

Regulatory relationships of HXT4

• Transcription of the HXT4 gene is regulated by Gcr1p and Gcr2p in the yeast S. cerevisiae [15].

Other interactions of HXT4

• Overproduction of Gcr1p from an inducible promoter resulted in a 15-64% increase in transcription of HXT4, depending on the growth conditions [15].
• We show that the dominant mutation GSF4-1, which impairs glucose repression of SUC2, results in a nonfunctional chimera of the transporters Hxt1p and Hxt4p [16].
• The defect of the low-affinity component was found to be due to a block of transcription of the RAG1 gene by the hexokinase mutation [17].
• Therefore, it seems that the enolase and a functional glycolytic flux are necessary for induction of expression of the Rag1 glucose permease in K. lactis [18].
• In the absence of glucose, repression of LGT1 expression required the transcription factor Rgt1p [12].

Analytical, diagnostic and therapeutic context of HXT4

• The V(max) of glucose transport dropped considerably and Northern blot analysis showed that induction of the HXT1, HXT2 and HXT4 genes was strongly reduced [19].

References