Structure And Evolution Of The Eukaryotic Fancj-like Protein

The FANCJ-like protein family is a class of ATP-dependent helicases that cancatalytically unwind duplex DNA along the5’-3’direction, which is involved in DNAdamage repair, homologous recombination and the resolution of G-quadruplex DNA, and itplays a critical role in maintaining genome integrity, In this study, classification andIdentification of FANCJ-like family helicase is based on the complete genome sequence.wesystemically analyzed FNACJ-like proteins from47eukaryotic species and their sequencesdiversity, origin and evolution, motif organization patterns and spatial structure differenceswere discussed. The result of this study was as follows:160FANCJ-like proteins are identified from51species, The results of phylogeneticshowed that there are wholly4members, including XPD, CHL1, RTEL1and FANCJ, exist inFNACJ-like protein family in eukaryotes, but some members were deficient in fungi andsome insects dramatically. For example, the Zygomycota fungi lost RTEL1, Basidiomycotaand Ascomycota fungi lost RTEL1and FANCJ, Diptera insect also lost FANCJ.The configuration analysis of intron in the FANCJ-like protein domain, the rusult showthat the introns inserted location in the same class FANCJ-like proteins of samespecies(higher plants or animals), the number and phase are consistent with each other; Thereare a few sites are consistent in different class species; Four types of FANCJ-like proteinsintrons insertion site, number and phase is greatly different, even there was no commonconservative introns insertion site in four FANCJ-like protein domains. This shows that thedifferentiation in the four members have been finished before the eukaryotes evolution, thenthe insertion events of intron was happened.Analysis the difference of the FANCJ-like protein conserved motifs and spatialstructures Show that FANCJ-like proteins not only contain canonical motor domains HD1andHD2, but also contain3unique domains Fe-S, Arch and Extra-D inserted in HD1. Fe-S andArch domains are relatively conservative, but the Extra-D domain was missing in XPD,which is completely different in other3members. There are7,10and2specific motifs werefound from unique domains Fe-S, Arch and Extra-D, and5and12specific motif were foundin HD1and HD2domains except reported conserved motifs. Based on arrangement pattern of conserved motifs, RTEL1and FANCJ are more closer and share two specific motifs Vb2andVc in HD2domain, which are likely related to their G-quadruplex DNA resolving activity.CHL1, RTEL1and FANCJ have8consensus motifs and XPD is obviously different withthem.Based on the results of above analysis and previous report,we presented the process ofthe FANCJ-like protein evolution, FACNJ-like proteins were originated from a helicase,which has a HD1domain containing extra Fe-S domain and Arch domain. Only XPDothlogus exist in bacteria and archaea, eukaryotes possessed4classes of FANCJ-likeproteins by three continuous gene duplication events and followed specialization before theemerging of multicellular eukaryotic organisms.