The interaction between the Dbf4 ortholog Chiffon and Gcn5 is conserved in Dipteran insect species

• Published in: Insect molecular biology 2022-12, Vol.31 (6), p.734-746
• Main Authors: George, Smitha, Blum, Hannah R., Torres‐Zelada, Eliana F., Estep, Grace N., Hegazy, Youssef A., Speer, Gina M., Weake, Vikki M.
• Format: Article
• Language: English
• Subjects: Acetylation; Animals; Australia; Biological activity; Cell Cycle; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; CHAT; Chiffon; Deoxyribonucleic acid; Diptera; DNA; DNA biosynthesis; DNA Replication; Drosophila; Drosophila - metabolism; Drosophila Proteins - genetics; Fruit flies; Gcn5; Histone acetyltransferase; Histone H3; Histones; Insects; Kinases; Pest control; Polypeptides; Protein Serine-Threonine Kinases; Replication; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Sheep; Transcription factors; Vector-borne diseases; VP16 protein; Yeasts; Yellow fever
• ISSN: 0962-1075; 1365-2583
• DOI: 10.1111/imb.12800

Chiffon is the sole Drosophila ortholog of Dbf4, the regulatory subunit for the cell‐cycle kinase Cdc7 that initiates DNA replication. In Drosophila, the chiffon gene encodes two polypeptides with independent activities. Chiffon‐A contains the conserved Dbf4 motifs and interacts with Cdc7 to form the Dbf4‐dependent Kinase (DDK) complex, which is essential for a specialized form of DNA replication. In contrast, Chiffon‐B binds the histone acetyltransferase Gcn5 to form the Chiffon histone acetyltransferase (CHAT) complex, which is necessary for histone H3 acetylation and viability. Previous studies have shown that the Chiffon‐B region is only present within insects. However, it was unclear how widely the interaction between Chiffon‐B and Gcn5 was conserved among insect species. To examine this, we performed yeast two‐hybrid assays using Chiffon‐B and Gcn5 from a variety of insect species and found that Chiffon‐B and Gcn5 interact in Diptera species such as Australian sheep blowfly and yellow fever mosquito. Protein domain analysis identified that Chiffon‐B has features of acidic transcriptional activators such as Gal4 or VP16. We propose that the CHAT complex plays a critical role in a biological process that is unique to Dipterans and could therefore be a potential target for pest control strategies. The Dbf4 ortholog Chiffon has an extended C‐terminal domain in all insects, but its sequence has diverged in different orders. The C‐terminal domain of Chiffon (Chiffon‐B) interacts with Gcn5 by yeast two‐hybrid in Drosophila and other Diptera, but this interaction was not detected in other insects. In Diptera, Chiffon‐B contains sequences that are characteristic of acidic activation domains that are found in well‐characterized transcription factors such as Gal4 and VP16. Schematic illustrating the interactions of the N‐ and C‐terminal domains of Chiffon. The N‐terminal domain, which is conserved in fungi and animals, interacts with Cdc7. The extended C‐terminal domain that is only present in insects interacts with Gcn5 in Drosophila and other Diptera to form the CHAT complex.