Structure‐based analysis of Clot as a thioredoxin‐related protein of 14 kDa in Drosophila via experimental and computational approaches

Abstract

The clot gene is required for the biosynthesis of drosopterins, the red components of Drosophila eye pigments. However, the enzymatic role of Clot in Drosophila eye pigment formation and the molecular mechanisms underlying Clot function are not fully elucidated. In this study, we cloned and characterized Clot derived from Drosophila cDNA, and results showed that Clot exhibited ∼30% sequence identity with mammalian TRP14. In addition, we reported the three-dimensional structure of Drosophila Clot based on homology modeling. Furthermore, we identified NFκB as a novel Clot substrate using the I-TASSER program. The NFκB fragment can bind near the active site of Clot. These findings predicted the novel regulatory mechanisms underlying Clot function in the pyrimidodiazepine synthesis pathway and increased the understanding of the molecular mechanisms and physiological function of Clot in Drosophila eye pigment formation.

Pterin-based pigmentation in animals

“…Isoxanthopterin biosynthesis is also impaired in lix mutants, which lack activity of a yet unidentified dihydropterin oxidase that acts upstream of XDH [22]. Other genes linked to disruptions of key steps in the biosynthesis of drosopterin and aurodrosopterin in the eye of fruit flies include several homologues of mammalian genes involved with pterin and purine metabolism [125][126][127][128][129][130][131] (figure 2c), as well as the fruit fly gene for pyrimidodiazepine synthase [132]. These results suggest that the biosynthesis of colourful pterins shares the initial conversion steps of the main 'de novo' BH4 pathway before diverging into parallel pigment-related pathways [23].…”

Thioredoxin‐related protein of 14 kDa as a modulator of redox signalling pathways

“…Less than 20 publications can today be found in PubMed on TRP14 (TXNRD17), and with such few studies published on this protein, it is highly likely that additional unknown functions of TRP14 will be revealed in the coming years. Recently, it was suggested that the clot gene of Drosophila melanogaster , essential for synthesis of the red eye pigment of the fly, encodes for a TRP14 orthologue (Kim, ). However, the protein has a typical glutaredoxin active site motif (WCPYC) and indeed exerts high glutaredoxin‐like activities, although it has a predicted overall structure closely similar to TRP14 and also interacts with NF‐κB signalling (Kim, ).…”

“…Recently, it was suggested that the clot gene of Drosophila melanogaster , essential for synthesis of the red eye pigment of the fly, encodes for a TRP14 orthologue (Kim, ). However, the protein has a typical glutaredoxin active site motif (WCPYC) and indeed exerts high glutaredoxin‐like activities, although it has a predicted overall structure closely similar to TRP14 and also interacts with NF‐κB signalling (Kim, ). Thus, the clot protein seems to have features of both glutaredoxins and TRP14.…”