Disease relevance of HAL1

• In cells overexpressing HAL1, sodium toxicity seems to be counteracted by an increased accumulation of potassium [1].
• In the present work, the yeast gene HAL1 was introduced into tomato (Lycopersicon esculentum Mill.) by Agrobacterium tumefaciens-mediated transformation [2].
• In order to enhance its constitutive expression in plants, the HAL1 gene was cloned in a pBiN19 plasmid under control of the 35S promoter with a double enhancer sequence from the cauliflower mosaic virus and the RNA4 leader sequence of the alfalfa mosaic virus [3].

High impact information on HAL1

• The HAL1 protein could interact with the transport systems which determine intracellular K+ homeostasis [1].
• The HAL1 gene and encoded protein are conserved in plants, being induced in these organisms by salt stress and abscisic acid [1].
• The Gcn4p transcriptional activator binds in vitro to the same CRE(HAL1) and is necessary for up-regulated HAL1 expression in vivo, indicating a dual control mechanism by a repressor-activator pair occupying the same promoter target sequence. gcn4 mutants display a strong sensitivity to elevated K(+) or Na(+) concentrations in the growth medium [4].
• Down-regulation of HAL1 under normal growth conditions requires specific binding of Sko1p to CRE(HAL1) and the corepressor gene SSN6 [4].
• The introduction of both the neomycin phosphotransferase II and HAL1 genes was assessed in primary transformants (TG1) by polymerase chain reaction analysis and Southern hybridisation [3].

Biological context of HAL1

• Here we demonstrate that the ion homeostasis determinant, HAL1, is regulated by two antagonistically operating bZIP transcription factors, the Sko1p repressor and the Gcn4p activator [4].
• The expression of the HAL1 gene was determined by Northern analysis, and the diploid level of transgenic plants was confirmed by flow cytometry [3].
• Southern blotting analysis indicated that HAL1 gene had been integrated into all of the transgenic plants' genomes [5].

Associations of HAL1 with chemical compounds

• Overexpression of HAL1 did not increase NaCl tolerance in galactose medium [6].

Other interactions of HAL1

• The effect of HAL1 on intracellular Na+ was mediated by the PMR2/ENA1 gene, corresponding to a major Na+ efflux system [6].
• The effect of HAL1 on intracellular K+ was independent of the TRK1 and TOK1 genes, corresponding to a major K+ uptake system and to a K+ efflux system activated by depolarization, respectively [6].

Analytical, diagnostic and therapeutic context of HAL1

• The halotolerance observed confirmed the inheritance of the trait and supports the potential usefulness of the HAL1 gene of S. cerevisiae as a molecular tool for genetic engineering of salt-stress protection in other crop species [3].

References