A subset of GAF domains are evolutionarily conserved sodium sensors

Cann, M

Abstract

Most organisms maintain a transmembrane sodium gradient for cell function. Despite the importance of Na+ in physiology, no directly Na+-responsive signalling molecules are known. The CyaB1 and CyaB2 adenylyl cyclases of the cyanobacterium Anabaena PCC 7120 are inhibited by Na+. A D360A mutation in the GAF-B domain of CyaB1 ablated cAMP-mediated autoregulation and Na+ inhibition. Na+ bound the isolated GAF domains of CyaB2. cAMP blocked Na+ binding to GAF domains but Na+ had no effect on cAMP binding. Na+ altered GAF domain structure indicating a mechanism of inhibition independent of cAMP binding. ΔcyaB1 and ΔcyaB2 mutant strains did not grow below 0.6 mM Na+ and ΔcyaB1 cells possessed defects in Na+/H+ antiporter function. Replacement of the CyaB1 GAF domains with those of rat phosphodiesterase type 2 revealed that Na+ inhibition has been conserved since the eukaryotic/bacterial divergence. CyaB1 and CyaB2 are the first identified directly Na+-responsive signalling molecules that function in sodium homeostasis and we propose a subset of GAF domains underpin an evolutionarily conserved Na+ signalling mechanism.

Citation

Cann, M. (2007). A subset of GAF domains are evolutionarily conserved sodium sensors. Molecular Microbiology, 64(2), 461-472. https://doi.org/10.1111/j.1365-2958.2007.05669.x

• Journal Article Type: Article
• Publication Date: Apr 1, 2007
• Deposit Date: Jan 17, 2008
• Publicly Available Date: Nov 27, 2014
• Journal: Molecular Microbiology
• Print ISSN: 0950-382X
• Electronic ISSN: 1365-2958
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 64
• Issue: 2
• Pages: 461-472
• DOI: https://doi.org/10.1111/j.1365-2958.2007.05669.x
• Public URL: https://durham-repository.worktribe.com/output/1536224