Meiosis entails sorting and separating both homologous and sister chromatids. The mechanisms for connecting sister chromatids and homologs during meiosis are highly conserved and include specialized forms of the cohes...
Meiosis entails sorting and separating both homologous and sister chromatids. The mechanisms for connecting sister chromatids and homologs during meiosis are highly conserved and include specialized forms of the cohesin complex and a tightly regulated homolog synapsis/recombination pathway designed to yield regular crossovers between homologous chromatids. Drosophila male meiosis is of special interest because it dispenses with large segments of the standard meiotic script, particularly recombination, synapsis and the associated structures. Instead, Drosophila relies on a unique protein complex composed of at least two novel proteins, SNM and MNM, to provide stable connections between homologs during meiosis I. Sister chromatid cohesion in Drosophila is mediated by cohesins, ring-shaped complexes that entrap sister chromatids. However, unlike other eukaryotes Drosophila does not rely on the highly conserved Rec8 cohesin in meiosis, but instead utilizes two novel cohesion proteins, ORD and SOLO, which interact with the SMC1/3 cohesin components in providing meiotic cohesion.
Transcriptional regulation of gene expression is enacted mainly through binding of transcription factors (TFs) to specific, short DNA sites in cis-regulatory regions of genes. Most TFs are members of protein families ...
Transcriptional regulation of gene expression is enacted mainly through binding of transcription factors (TFs) to specific, short DNA sites in cis-regulatory regions of genes. Most TFs are members of protein families that share a common DNA-binding domain and thus recognize similar DNA-binding sequences. It is not well understood why paralogous TFs often bind different genomic target sitesin vivoto effect different regulatory programs, despite apparently recognizing the same sequence motifs. Here, we designed custom protein-binding microarrays (PBMs) to analyze the DNA-binding specificities of twoSaccharomyces cerevisiaebasic helix-loop-helix (bHLH) proteins, Tye7 and Cbf1, as a model system. Our data reveal that E-box DNA-binding sequences (CAnnTG), when tested in the context of their native genomic flanking sequences, are bound differently by Cbf1 and Tye7. Computational models of the PBM data indicate that DNA sequence features located in the genomic sequences outside the E-box contribute to DNA-binding specificityin vitro. Our analyses suggest that these flanking regions affect DNA-binding specificity indirectly by influencing the three-dimensional structure of the E-box binding sites. Finally, we show that these subtle differences in intrinsic sequence preferences of Cbf1 and Tye7in vitrohelp to explain their differential DNA-binding preferencesin vivo. Our results provide further evidence that the local shape of DNA-binding sites may be an important feature in distinguishing the DNA-binding preferences among paralogous TFs and thus may play a widespread role in determining how transcriptional regulatory specificity within TF families is achieved.
Cells offer natural examples of highly efficient networks of nanomachines. Accordingly, both intracellular and intercellular communication mechanisms in nature are looked to as a source of inspiration and instruction ...
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