TY - JOUR T1 - Analysis of human immunoglobulin VDJ and DJ rearrangements shows N region synthesis by concatenation of cytosine-rich strands preferentially originating from trimmed germline gene segments JF - bioRxiv DO - 10.1101/248021 SP - 248021 AU - Funck, Tina AU - Barnkob, Mike Bogetofte AU - Holm, Nanna AU - Ohm-Laursen, Line AU - Mehlum, Camilla Slot AU - Möller, Sören AU - Barington, Torben Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/01/23/248021.abstract N2 - The formation of non-templated (N) regions during immunoglobulin gene rearrangement is a major contributor to antibody diversity. To gain insights into the mechanisms behind this, we studied the nucleotide composition of N regions within 29,962 unique human VHDJH-rearrangements and 8,728 unique human DJH-rearrangements containing exactly one identifiable D-gene segment and thus two N regions, N1 and N2. We found a distinct decreasing content of cytosine (C) and increasing content of guanine (G) across each N region, suggesting that N regions are typically generated by concatenation of two 3’-overhangs synthesized by addition of nucleoside triphosphates with a preference for dCTP. This challenges the general assumption that the terminal deoxynucleotidyl transferase favors dGTP in vivo. Furthermore, we found that the G and C gradients depended strongly on whether the germline gene segments were trimmed or not. Our data show that C-enriched N addition preferentially happens at trimmed 3’-ends of VH-, D-, and JH-gene segments indicating a dependency of the transferase mechanism upon the nuclease mechanism. ER -