Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GARP homologues constitute a large family of DNA-binding proteins in plants that may be needed for a variety of key cellular functions including regulation of transcription, phosphotransfer signaling, and differentiation. However, no member of this gene family has been reported to date in yeast, animals, or protozoan parasites. We have identified four genes with putative GARP domains in the Giardia lamblia genome (GARP-like protein or GLP). The glp1 mRNA levels increased slightly during encystation. Epitope-tagged GLP1 localized to both nuclei and the proportion of stained Giardia cells increased by 10-fold during encystation. Recombinant GLP1 specifically bound to both the regulated cwp1 and constitutive ran gene promoters in their double-stranded configurations. The C-terminal region of GLP1 containing the GARP-like domain encoded the DNA binding activity. Mutation analysis revealed that an (A/G)ATCN sequence was required for binding of GLP1 to these promoters. We also found that GLP2 recognized similar binding sites. Using mutated plasmids and transfection assays, we demonstrated that the GLP1/2 binding sites are positive cis-acting elements of the cwp1 and ran gene promoters in both trophozoites and encysting cells. GLP1 is the first GARP family gene found in protozoan parasites. Our results suggest that GLP1 may be an important transcriptional activator and that its binding sites are positive promoter elements for certain Giardia genes.
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PMID:Novel plant-GARP-like transcription factors in Giardia lamblia. 1631 Feb 59

Nitrogen and phosphorus are two major soil nutrients required for plant growth. Because requirements of both these elements are interdependent, acquisition of one must be balanced with that of the other. However, the mechanism underlying this balanced acquisition remains unclear. Here, we show by in vivo luciferase imaging that the presence of nitrogen sources is a pre-requisite for strong activation of phosphate starvation responses. In addition, we also show that nitrate rather than ammonium is a potent modulator of phosphate starvation-induced gene expression. Furthermore, protoplast-based transient expression assay and chromatin immunoprecipitation assay demonstrate that NIGT1 GARP-type transcriptional repressors, which are encoded by nitrate-inducible genes, directly bind to and repress the promoters of genes encoding SPX proteins. Consistent with the role of SPX proteins in the suppression of the PHR1 transcriptional activator, the master regulator for phosphate starvation responses, nitrate-dependent enhancement of phosphate starvation responses, such as accumulation of anthocyanin and promotion of root hair growth and phosphate uptake, was less evident in the nigt1.1-nigt1.4 quadruple mutant. Consistently, NIGT1 overexpression alleviated the reduction in phosphate uptake under phosphate-replete conditions. We further reveal the intricate feedback regulations involving PHR1, NIGT1, and SPX family proteins in the phosphate starvation signalling network. Importantly, results of mutant protoplast-based assays and in planta analysis using NIGT1 overexpression in the spx1 spx2 double mutant indicated that the NIGT1-SPX-PHR cascade mediates nitrogen status-responsive regulation of phosphate uptake and starvation signalling. These findings uncover the mechanism underlying the balanced acquisition of nitrogen and phosphorus.
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PMID:Nitrate-inducible NIGT1 proteins modulate phosphate uptake and starvation signalling via transcriptional regulation of SPX genes. 3181 79