Fig. 9: Potential ubiquitin acceptor lysines in BCL10 CARD are critical for CBM complex formation.
From: LUBAC modulates CBM complex functions downstream of TRAF6 in T cells
a Top view of one helical turn of the BCL10-MALT1 core complex obtained by cryo-EM (PDB ID 6GK2)6. MALT1 death domain (DD) is depicted in orange, BCL10 subunits in pink, purple, blue and turquois. BCL10 CARD-CARD interactions and BCL10-MALT1 interface are indicated by arrows. b Top: Side view of the BCL10 protein model obtained by the BCL10-MALT1 complex cryo-EM density (PDB ID 6GK2)6 licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/CC-BY-4.0). Postulated ubiquitin acceptor sites in BCL10 are highlighted in yellow, other lysine are shown in purple. Bottom: Schematic diagram of the BCL10 helical assembly. Each CARD is represented as a hexagon, and the three interfaces are indicated accordingly. c Zoom into BCL10-BCL10 interface I (left) and interface II (right), showing lysines 63 and 31 in yellow, respectively. Interacting residues are shown in stick representation. d Molecular modeling of lysine to arginine exchange at K63 (BCL10 interface I) and K31 (BCL10 interface II). Potential positions of arginine rotamers are shown in light grey and the most energetically preferred position in yellow. e Flag-tagged BCL10 WT, KK31/63RR and R42E co-expressed with HA-tagged BCL10 WT in HEK293T. After anti-Flag IP, binding of Flag- and HA-BCL10 was analyzed by Western blot. f Zoom into the BCL10-MALT1 interface showing K17 of BCL10 juxtaposed to the MALT1 DD. g Flag-tagged BCL10 WT, K17R, KKK17/31/63RRR and L104R were co-expressed with HA-tagged MALT1 WT in HEK293T. After anti-Flag IP, binding of Flag-BCL10 and HA-MALT1 was analyzed by Western blot. h BCL10 KO Jurkat T cells reconstituted with Strep-tagged (ST) BCL10 WT, K17R, KK31/63RR, KKK17/31/63RRR and L104R were stimulated with P/I. Strep-Tactin pulldown (Strep-PD) was performed and binding of BCL10-MALT1 and BCL10-CARD11 was analyzed by Western blot. Western blots in (e, g, h) show representative data from two independent experiments. kDa kilodalton.
