CabP (SPD_0077) is a cyclic di-AMP receptor and potassium-transport regulator in Streptococcus pneumoniae D39. It directly interacts with the membrane potassium transporter SPD_0076 and supports potassium uptake under potassium limitation. Elevated cyclic di-AMP weakens the CabP-transporter interaction and reduces potassium uptake. CabP is the regulatory component rather than the transmembrane pore.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006813 potassium ion transport | IEA GO_REF:0000002 | MODIFY | Summary: The directly demonstrated role is regulation of potassium transport. Reason: The protein directly interacts with and regulates the conducting component. This is a role refinement to potassium-transport regulation, rather than an assignment of pore-mediated ion translocation to the soluble regulator. Proposed replacements: regulation of potassium ion transport Supporting Evidence: PMID:24272783 we showed that CabP directly interacted with a potassium transporter (SPD_0076) and that both proteins were required for pneumococcal growth in media with low concentrations of potassium. PMID:24272783 the interaction between CabP and SPD_0076 and the efficiency of potassium uptake were impaired by elevated c-di-AMP in pneumococci. |
| GO:0180001 cyclic-di-AMP binding | IDA PMID:24272783 Cyclic di-AMP impairs potassium uptake mediated by a cyclic ... | NEW | Summary: Cyclic di-AMP binding is an experimentally established receptor activity. Reason: Purified CabP (SPD_0077) from S. pneumoniae D39 binds cyclic di-AMP specifically. This directly measured molecular activity merits its own annotation alongside regulation of potassium transport. Supporting Evidence: PMID:24272783 We demonstrated that CabP specifically bound c-di-AMP |
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