hudek-molecularand-2013.pdf (2.4 MB)
Molecular and cellular characterisation of the zinc uptake (Znu) system of Nostoc punctiforme
journal contribution
posted on 2013-01-01, 00:00 authored by Lee Hudek, L Pearson, Agnes MichalczykAgnes Michalczyk, B Neilan, Leigh AcklandLeigh AcklandMetal homoeostasis in cyanobacteria is based on uptake and export systems that are controlled by their own regulators. This study characterises the zinc uptake (Znu) system in Nostoc punctiforme. The system was found to comprise of three subunits in an ACB operon: a Zn2+-binding protein (ZnuA18), a transmembrane domain (ZnuB) and an ATPase (ZnuC). These proteins are encoded within the znu operon regulated by a zinc uptake transcription repressor (Zur). Interestingly, a second Zn2+-binding protein (ZnuA08) was also identified at a distal genomic location. Interactions between components of the ZnuACB system were investigated using knockouts of the individual genes. The znuA08-, znuA18-, znuB- and znuC- mutants displayed overall reduced znuACB transcript levels, suggesting that all system components are required for normal expression of znu genes. Zinc uptake assays in the Zn2+-binding protein mutant strains showed that the disruption of znuA18 had a greater negative effect on zinc uptake than disruption of znuA08. Complementation studies in Escherichia coli indicated that both znuA08 and znuA18 were able to restore zinc uptake in a znuA- mutant, with znuA18 permitting the highest zinc uptake rate. The N. punctiforme zur was also able to complement the E. coli zur- mutant.
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Journal
FEMS microbiology ecologyVolume
86Issue
2Pagination
149 - 171Publisher
Wiley-BlackwellLocation
Oxford, EnglandPublisher DOI
ISSN
0168-6496eISSN
1574-6941Language
engPublication classification
C1 Refereed article in a scholarly journalUsage metrics
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