Analysis of a Putative Promoter in Mycobacteriophage JacoRen57

JacoRen57 is a cluster AB mycobacteriophage that infects Mycobacterium smegmatis mc²155. We recently reported on the characterization of a putative promoter in JacoRen57 using an mCherry reporter construct. This promoter is present in a gap upstream of a gene that is present in all AB phages. In all cases, these are forward genes immediately following a long series of reverse genes. The genes are most frequently identified as a RecA-like DNA recombinases but also as RepA by bioinformatics. To further analyze this putative promoter and gene product, NWC Molecular Genetics students cloned the RecA-like DNA recombinase into an E. coli expression vector with a TVMV removable N-terminal His-tag. They expressed and we purified the tagged protein and are using it to immunize Balb/c mice. We plan to use the antiserum to confirm RecA-like DNA recombinase expression patterns when JacoRen57 infects M. smegmatis

Investigating the Putative RecA-Like Recombinase Gene

Our Biochemistry: Molecular Genetics class has partnered with the Immunology class to investigate the expression of JacoRen57’s gene 50. The bacteriophage JacoRen57 – found in Sioux Center, Iowa (accession: MK279840). JacoRen57’s genome has sequenced by Pittsburg SEA-PHAGES Institute and fully annotated by Northwestern College students in 2018. A region between gene 49 and 50 caught our attention as there is a large gap between these genes. Almail et al., investigated if this is a transcription regulatory region for genes 49 and/or 50 (2021). This work demonstrated the region has a regulatory function in the direction of gene 50. Based on comparison genomics, gene 50 is a putative RecA-like recombinase (Almail et al., 2019). This protein has several functions including guiding the recombination of DNA within a gene. RecA-like recombinase allows the virus to evolve into new variants which can improve infection and replication. This is crucial for creating diversity in the genome and DNA repair mechanisms (Galletto and Kowalczykowski, 2007). To continue examination of gene 50 expression, we are working towards developing antibodies for this protein. To do this, the first step is to create an expression construct (Figure 1), express the protein in bacteria, purify the protein, and then use the purified protein to inoculate mice. This poster describes the construction of the expression vector. This work will provide valuable insight into the expression of gene 50, the RecA-like recombinase

\u3ci\u3eDrosophila\u3c/i\u3e Muller F Elements Maintain a Distinct Set of Genomic Properties Over 40 Million Years of Evolution

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu