Biology subjects

Comstra, H. S.

Publications and source records attributed to Comstra, H. S..

4 recordsLinked to original sources

bioRxiv2023

A bioinformatics screen reveals Hox and chromatin remodeling factors at the Drosophila histone locus

Cells orchestrate histone biogenesis with strict temporal and quantitative control. To efficiently regulate histone biogenesis, the repetitive Drosophila melanogaster replication-dependent histone genes are arrayed and clustered at a single locus. Regulatory factors concentrate in a nuclear body known as the histone locus body (HLB), which forms around the locus. Historically, HLB factors are largely discovered by chance, and few are known to interact directly with DNA. It is therefore unclear how the histone genes are specifically targeted for unique and coordinated regulation. To expand the list of known HLB factors, we performed a candidate-based screen by mapping 30 publicly available ChIP datasets and 27 factors to the Drosophila histone gene array. We identified novel transcription factor candidates, including the Drosophila Hox proteins Ultrabithorax, Abdominal-A and Abdominal-B, suggesting a new pathway for these factors in influencing body plan morphogenesis. Additionally, we identified six other transcription factors that target the histone gene array: JIL-1, Hr78, the long isoform of fs(1)h as well as the generalized transcription factors TAF-1, TFIIB, and TFIIF. Our foundational screen provides several candidates for future studies into factors that may influence histone biogenesis. Further, our study emphasizes the powerful reservoir of publicly available datasets, which can be mined as a primary screening technique.

molecular biology↗

bioRxiv2022

MSL2 targets histone genes in Drosophila virilis

Histone genes are amongst the most evolutionary conserved in eukaryotic genomes, yet cis-regulatory mechanisms of histone gene regulation differ considerably amongst species. In Drosophila melanogaster, an interaction between GA-rich cis elements in the H3/H4 promoter and the GA-binding transcription factor CLAMP is important for promoting histone gene regulation and factor recruitment to the locus. CLAMP also participates in male dosage compensation by recruiting the Male Specific Lethal Complex (MSLc) to the X-chromosome. We discovered that the male-specific protein of MSLc, MSL2, is recruited to the autosomal major histone locus in D. virilis but not to the minor locus or to the single histone locus in other species. While the histone coding sequences are well conserved between species, the critical GA-rich cis elements in the H3/H4 promoter are poorly conserved between D. melanogaster and D. virilis. We show that CLAMP still targets the two D. virilis histone loci in vivo. Further, CLAMP interacts with the D. virilis H3/H4 promoter in vitro, even when the poorly-conserved GA-rich cis elements are deleted, indicating that the protein interacts differently with the D. virilis promoter than it does with the D. melanogaster promoter. Since CLAMP and MSL2 directly interact in D. melanogaster, we propose that D. virilis CLAMP recruits MSL2 to an ectopic autosomal site through interaction with X-like cis elements. Further, localization of MSL2 to one of the D. virilis histone loci suggests that the loci are regulated differently and that males and females have different requirements for histone gene regulation.

genetics↗

bioRxiv2022

A cost-free CURE: Using bioinformatics to identify DNA-binding factors at a specific genomic locus

Research experiences provide diverse benefits for undergraduates. Many academic institutions have adopted course-based undergraduate research experiences (CUREs) to improve student access to research opportunities. However, potential instructors of a CURE might still face financial or practical hurdles that prevent implementation. Bioinformatics research offers an alternative that is free, safe, compatible with remote learning, and may be more accessible for students with disabilities. Here, we describe a bioinformatics CURE that leverages publicly available datasets to discover novel proteins that target an instructor-determined genomic locus of interest. We use the free, user-friendly bioinformatics platform Galaxy to map ChIP-seq datasets to a genome, which removes the computing burden from students. Both faculty and students directly benefit from this CURE, as faculty can perform candidate screens and publish CURE results. Students gain not only basic bioinformatics knowledge, but also transferable skills, including scientific communication, database navigation, and primary literature experience. The CURE is flexible and can be expanded to analyze different types of high-throughput data or to investigate different genomic loci in any species.

scientific communication and education↗

bioRxiv2022

Max is likely not at the Drosophila histone locus

The histone locus body (HLB) is a conserved nuclear body that regulates histone mRNA production in metazoans. While some HLB components are known, there are likely uncharacterized factors that target the histone locus. We identified the Drosophila melanogaster protein Max, which interacts with known HLB member Myc, as an HLB candidate. We mapped Max ChIP-seq and ChIP-nexus datasets, which revealed encouraging signal over the histone gene array. However, we discovered that Max does not colocalize with HLB components on polytene chromosomes. Therefore, we conclude that Max is likely not at the D. melanogaster histone locus.

genetics↗