Disease relevance of z

• Zeste protein purified from Drosophila cells or from E. coli expressing the zeste gene activates Ubx transcription in vitro [1].
• An interesting aspect for further analysis is the apparent infrequency in the zeste-white region of alkylation-induced chromosomal breakage, as observed by various investigators for MMS, EMS and MNNG [2].
• White spots on the other hand were equally large in size, irrespective of inducing agent and about twice the size of the chemically-induced red spots, implying a faster and more direct action for fixation of deletions than for the production of MMS induced shifts in eye color from zeste to red [3].

High impact information on z

• Enhancer of Zeste is a Polycomb Group protein essential for the establishment and maintenance of repression of homeotic and other genes [4].
• Zeste encodes a sequence-specific transcription factor that activates the Ultrabithorax promoter in vitro [1].
• In contrast to the relative insensitivity of eye-color pigmentation and dosage compensation to genomic position, the transduced white DNA segments differed widely in their interactions with the zeste mutation, ranging from greater than normal repression by zeste to insensitivity to the presence of zeste [5].
• Drosophila genes Posterior Sex Combs and Suppressor two of zeste encode proteins with homology to the murine bmi-1 oncogene [6].
• We have used this technique to test the proposal of Jack and Judd that the zeste locus of Drosophila melanogaster cannot repress the activity of unpaired alleles at the white locus [7].

Biological context of z

• Here, we have sought to dissect the requirements for transcriptional activation by the Drosophila trxG protein Zeste, a DNA-binding activator of homeotic genes [8].
• Reconstituted transcription reactions established that the Brahma (BRM) chromatin-remodeling complex is essential for Zeste-directed activation on nucleosomal templates [8].
• Mutagenesis studies determined (T/C/g)GAGTG(A/G/c) as the consensus Zeste recognition sequence [9].
• We compare the DNA-binding properties of Zeste with those of classical tri-helical DBDs harboring a helix-turn-helix motif and suggest a model for Zeste-DNA recognition [9].
• It is shown here that the CURLY LEAF gene of Arabidopsis is necessary for stable repression of a floral homeotic gene and encodes a protein with homology to the product of the Polycomb-group gene Enhancer of zeste [10].

Anatomical context of z

• Using affinity-purified anti-zeste antibodies, we find that wild-type salivary gland chromosomes contain about 60 strong bands of zeste immunofluorescence at specific cytological locations [11].
• Nearly ubiquitous expression of the zeste-lacZ gene is found in late embryos and first instar larvae, but disappears almost completely except in brain and gonads by third instar larva [11].
• Molecular cloning, germ-line transformation, and transcriptional analysis of the zeste locus of Drosophila melanogaster [12].
• Using immunoprecipitation of in vivo formaldehyde-fixed chromatin in phenotypically diverse cultured cell lines, we have mapped PRC1 components, the histone methyl transferase (HMT) Enhancer of zeste (E(z)) and histone H3 modifications in active and inactive PcG-controlled regions [13].
• It also contains five binding sites for the zeste protein while the immediately adjacent testis element contains none [14].

Associations of z with chemical compounds

• The leucine zipper of Zeste mediates binding to MOR [8].
• A large region of the predicted zeste product is comprised almost exclusively of glutamine and alanine residues [15].
• The sequence of CA150 contains an extensive glutamine- and alanine-rich repeat that is found in transcriptional modulators such as GAL11 and SSN6 in Saccharomyces cerevisiae and Zeste in Drosophila melanogaster [16].
• Diepoxybutane-induced mutations of the Drosophila zeste locus were generated in an effort to obtain a null allele [17].
• The z1 lesion alters a lysine residue located between the N-terminal DNA-binding domain and the C-terminal hydrophobic repeats involved in Zeste self-interactions [18].

Physical interactions of z

• A Drosophila Polycomb group complex includes Zeste and dTAFII proteins [19].
• Drosophila Enhancer of zeste protein interacts with dSAP18 [20].
• Binding of eve protein is shown to exclude binding by zeste protein [21].
• In this report, we demonstrate that zeste mutations can also interact with those decapentaplegic mutations that exhibit transvection effects [22].
• Here we find that purified zeste protein binds to multiple sites just 5' of the initiation site of Ubx RNA [1].

Regulatory relationships of z

• These genetic data, when considered with our earlier biochemical experiments, demonstrate that zeste directly and potently activates Ubx transcription in vivo [23].
• This P repression effect occurs only in the presence of the zeste allele and is suppressed by Su(z)2 mutations [24].
• We have also shown that the expressivity of Scutoid is enhanced by zeste mutations. snail and escargot encode evolutionarily conserved zinc-finger proteins involved in the development of mesoderm and limbs [25].

Other interactions of z

• The Drosophila brahma complex is an essential coactivator for the trithorax group protein zeste [8].
• Because it is not required for Zeste to bind to chromatin, the BRM complex appears to act after promoter binding by the activator [8].
• Interestingly, although the Imitation Switch (ISWI) remodelers are potent nucleosome spacing factors, they are dispensable for transcriptional activation by Zeste [8].
• Transvection at the Scr gene is blocked by rearrangements that disrupt pairing, but is zeste independent [26].
• We present a model in which the dual transcriptional activities of Zeste and GAGA are an essential component of the mechanism that chooses which maintenance system is to be targeted to a given promoter [27].

Analytical, diagnostic and therapeutic context of z

• Transcription was analysed by Northern blot hybridisation in the wild-type and several mutants: wa, w67c23, we, wsp and zeste [28].
• Of 33 mutations of this X-linked gene isolated, 16 were associated with multilocus deletions of zeste and adjacent complementation groups, while the remainder were defects restricted to zeste undetectable by Southern blot analysis [17].
• The DNA sequence C/AGAGCGC/AGA, related to binding sites for GAF and Zeste transcription factors, was selected from a pool of degenerate PCR fragments for binding to the cytoplasmic protein of Drosophila preblastoderm embryos [29].
• In situ hybridization with probes from the white-roughest interval shows that the reduced TE's are truncated in the same region, 40-90 kb upstream of the white locus, well proximal to the zeste interaction site [30].

References