A tight tuneable range for Ni(II)-sensing and -buffering in cells

• Published in: Nature chemical biology Vol. 13; no. 4; pp. 409 - 414
• Main Authors: Foster, Andrew W., Pernil, Rafael, Patterson, Carl J., Scott, Andrew J. P., Pålsson, Lars-Olof, Pal, Robert, Cummins, Ian, Chivers, Peter T., Pohl, Ehmke, Robinson, Nigel J.
• Format: Journal Article
• Language: English
• Published: 06.02.2017
• ISSN: 1552-4450; 1552-4469
• DOI: 10.1038/nchembio.2310

The metal-affinities of metal-sensing transcriptional regulators co-vary with cellular metal concentrations over more than 12 orders of magnitude. To understand the cause of this relationship, we determined the structure of the Ni(II)-sensor InrS then created cyanobacteria ( Synechocystis PCC 6803) in which transcription of genes encoding a Ni(II)-exporter and a Ni(II)-importer were controlled by InrS variants with weaker Ni(II)-affinities. Variant strains were sensitive to elevated nickel and contained more nickel but the increase was small compared to the change in Ni(II)-affinity. All of the variant-sensors retained the allosteric mechanism which inhibits DNA binding upon metal binding but a response to nickel in vivo was only observed when the sensitivity was set to respond within a relatively narrow (less than 2 orders of magnitude) range of nickel-concentrations. The Ni(II)-affinity of InrS is attuned to cellular metal concentrations rather than the converse.