TY  - JOUR
AU  - Sieme, Daniel
AU  - Engelke, Michael
AU  - Rezaei-Ghaleh, Nasrollah
AU  - Becker, Stefan
AU  - Wienands, Jürgen
AU  - Griesinger, Christian
TI  - Autoinhibition in the Signal Transducer CIN85 Modulates B Cell Activation
JO  - Journal of the American Chemical Society
VL  - 146
IS  - 1
SN  - 0002-7863
CY  - Washington, DC
PB  - ACS Publications
M1  - FZJ-2024-02815
SP  - 399 - 409
PY  - 2024
AB  - Signal transduction by the ligated B cell antigen receptor (BCR) depends on the preorganization of its intracellular components, such as the effector proteins SLP65 and CIN85 within phase-separated condensates. These liquid-like condensates are based on the interaction between three Src homology 3 (SH3) domains and the corresponding proline-rich recognition motifs (PRM) in CIN85 and SLP65, respectively. However, detailed information on the protein conformation and how it impacts the capability of SLP65/CIN85 condensates to orchestrate BCR signal transduction is still lacking. This study identifies a hitherto unknown intramolecular SH3:PRM interaction between the C-terminal SH3 domain (SH3C) of CIN85 and an adjacent PRM. We used high-resolution nuclear magnetic resonance (NMR) experiments to study the flexible linker region containing the PRM and determined the extent of the interaction in multidomain constructs of the protein. Moreover, we observed that the phosphorylation of a serine residue located in the immediate vicinity of the PRM regulates this intramolecular interaction. This allows for a dynamic modulation of CIN85's valency toward SLP65. B cell culture experiments further revealed that the PRM/SH3C interaction is crucial for maintaining the physiological level of SLP65/CIN85 condensate formation, activation-induced membrane recruitment of CIN85, and subsequent mobilization of Ca2+. Our findings therefore suggest that the intramolecular interaction with the adjacent disordered linker is effective in modulating CIN85's valency both in vitro and in vivo. This therefore constitutes a powerful way for the modulation of SLP65/CIN85 condensate formation and subsequent B cell signaling processes within the cell.
LB  - PUB:(DE-HGF)16
C6  - 38111344
UR  - <Go to ISI:>//WOS:001140857600001
DO  - DOI:10.1021/jacs.3c09586
UR  - https://juser.fz-juelich.de/record/1025263
ER  -