Document Detail

Co(ll)-detection does not follow Kco(ll) gradient: channelling in Co(ll)-sensing.
MedLine Citation:
PMID:  23420021     Owner:  NLM     Status:  MEDLINE    
The MerR-like transcriptional activator CoaR detects surplus Co(ll) to regulate Co(ll) efflux in a cyanobacterium. This organism also has cytosolic metal-sensors from three further families represented by Zn(ll)-sensors ZiaR and Zur plus Ni(ll)-sensor InrS. Here we discover by competition with Fura-2 that CoaR has KCo(ll) weaker than 7 × 10(-8) M, which is weaker than ZiaR, Zur and InrS (KCo(ll) = 6.94 ± 1.3 × 10(-10) M; 4.56 ± 0.16 × 10(-10) M; and 7.69 ± 1.1 × 10(-9) M respectively). KCo(ll) for CoaR is also weak in the CoaR-DNA adduct. Further, Co(ll) promotes DNA-dissociation by ZiaR and DNA-association by Zur in vitro in a manner analogous to Zn(ll), as monitored by fluorescence anisotropy. After 48 h exposure to maximum non-inhibitory [Co(ll)], CoaR responds in vivo yet the two Zn(ll)-sensors do not, despite their tighter KCo(ll) and despite Co(ll) triggering allostery in ZiaR and Zur in vitro. These data imply that the two Zn(ll) sensors fail to respond because they fail to gain access to Co(ll) under these conditions in vivo. Several lines of evidence suggest that CoaR is membrane associated via a domain with sequence similarity to precorrin isomerase, an enzyme of vitamin B12 biosynthesis. Moreover, site directed mutagenesis reveals that transcriptional activation requires CoaR residues that are predicted to form hydrogen bonds to a tetrapyrrole. The Co(ll)-requiring vitamin B12 biosynthetic pathway is also membrane associated suggesting putative mechanisms by which Co(ll)-containing tetrapyrroles and/or Co(ll) ions are channelled to CoaR.
Carl J Patterson; Rafael Pernil; Samantha J Dainty; Buddhapriya Chakrabarti; Clare E Henry; Victoria A Money; Andrew W Foster; Nigel J Robinson
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Metallomics : integrated biometal science     Volume:  5     ISSN:  1756-591X     ISO Abbreviation:  Metallomics     Publication Date:  2013 Apr 
Date Detail:
Created Date:  2013-03-28     Completed Date:  2013-09-17     Revised Date:  2014-11-05    
Medline Journal Info:
Nlm Unique ID:  101478346     Medline TA:  Metallomics     Country:  England    
Other Details:
Languages:  eng     Pagination:  352-62     Citation Subset:  IM    
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MeSH Terms
Allosteric Regulation / drug effects
Anaerobiosis / drug effects
Bacterial Proteins / chemistry,  genetics,  metabolism*
Binding Sites
Binding, Competitive / drug effects
Cobalt / metabolism*,  pharmacology
DNA, Bacterial / metabolism
Escherichia coli / metabolism
Gene Expression Regulation, Bacterial / drug effects
Glucosides / metabolism
Models, Biological
Promoter Regions, Genetic / genetics
Protein Binding / drug effects
RNA, Messenger / genetics,  metabolism
Spectrometry, Fluorescence
Synechocystis / drug effects,  genetics,  metabolism*
Tetrapyrroles / metabolism
Uroporphyrins / metabolism
Grant Support
BB/E001688/1//Biotechnology and Biological Sciences Research Council; BB/H006052/2//Biotechnology and Biological Sciences Research Council
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA, Bacterial; 0/Glucosides; 0/RNA, Messenger; 0/Tetrapyrroles; 0/Uroporphyrins; 23599-55-5/hydrogenobyrinic acid; 3G0H8C9362/Cobalt; 69227-93-6/dodecyl maltoside

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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