Middle region of FancM interacts with Mhf and Rmi1 in silkworms, a species lacking the Fanconi anaemia (FA) core complex

Abstract

The Fanconi anaemia (FA) pathway is responsible for interstrand crosslink (ICL) repair. Among the FA core complex components, FANCM is believed to act as a damage sensor for the ICL-blocked replication fork and also as a molecular platform for FA core complex assembly and interaction with Bloom's syndrome (BS) complex that is thought to play an important role in the processing of DNA structures such as stalled replication forks. In the present study, we found that in silkworms, Bombyx mori, a species lacking the major FA core complex components (FANCA, B, C, E, F, and G), FancM is required for FancD2 monoubiquitination and cell proliferation in the presence of mitomycin C (MMC). Silkworm FancM (BmFancM) was phosphorylated in the middle regions, and the modification was associated with its subcellular localization. In addition, BmFancM interacted with Mhf1, a histone-fold protein, and Rmi1, a subunit of the BS complex, in the different regions. The interaction region containing at least these two protein-binding domains played an essential role in FancM-dependent resistance to MMC. Our results suggest that BmFancM also acts as a platform for recruitment of both the FA protein and the BS protein, although the silkworm genome seems to lose FAAP24, a FancM-binding partner protein in mammals.

Characterization of two adenine nucleotide translocase paralogues in the stink bug, <i>Plautia stali</i>

“…Two dsRNAs targeted to different regions in PsANTI1 and PsANTI2 were generated using pLit plasmids 14) by in vitro transcription using the T7 RiboMAX large-scale RNA production kit (Promega) according to the manufacturer's protocol. Venus is a variant of the green fluorescent protein, and dsVENUS was used as a negative control.…”

Selective modulation of the functions of a conserved DNA motor by a histone fold complex

“…Recent studies identified the histone fold complex MHF as a conserved regulator of these motor proteins (Singh et al 2010;Yan et al 2010;Lorenz et al 2012;Tao et al 2012;Yang et al 2012;Bhattacharjee et al 2013;Sugahara et al 2013;Wang et al 2013;Fox et al 2014;Zhao et al 2014). Here we provide genetic and biochemical evidence that the budding yeast MHF selectively regulates Mph1 functions to highlight the functional versatility of this family of histone fold complexes.…”

Differential contribution of the Fanconi anemia‐related proteins to repair of several types of DNA damage in cultured silkworm cells

“…In our previous experiment in silkworms, FA proteins were required for MMC resistance, whereas Mhf and BLM complex proteins were dispensable for such resistance; these results differed from those in human cells [4,26,28,35]. The difference between silkworms and humans suggests that some DNA repair pathways function differently in response to MMC treatment in these organisms.…”

“…We previously demonstrated that FancM is required for FancD2 monoubiquitination in response to MMC treatment in BmN4‐SID1 cells [28]. To determine whether the increased levels of monoubiquitinated FancD2 induced by HU and CPT depend on the presence of the FancM protein, the ratio of monoubiquitinated to non‐ubiquitinated FancD2 was measured under silencing of FancM mediated by two dsRNAs that were previously shown to be effective in this regard [28] (Fig.…”