| Full text | |
| Author(s): |
Mazzon, Ricardo Ruiz
[1]
;
Braz, Vania Santos
[2]
;
da Silva Neto, Jose Freire
[2]
;
Marques, Marilis do Valle
[1]
Total Authors: 4
|
| Affiliation: | [1] Univ Sao Paulo, Inst Ciencias Biomed, Dept Microbiol, BR-05508900 Sao Paulo - Brazil
[2] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Biol Celular & Mol & Bioagentes Patogen, BR-14049900 Sao Paulo - Brazil
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | BMC Genomics; v. 15, AUG 28 2014. |
| Web of Science Citations: | 10 |
| Abstract | |
Background: Intracellular zinc concentration needs to be maintained within strict limits due to its toxicity at high levels, and this is achieved by a finely regulated balance between uptake and efflux. Many bacteria use the Zinc Uptake Regulator Zur to orchestrate zinc homeostasis, but little is known regarding the transport of this metal across the bacterial outer membrane. Results: In this work we determined the Caulobacter crescentus Zur regulon by global transcriptional and in silico analyses. Among the genes directly repressed by Zur in response to zinc availability are those encoding a putative high affinity ABC uptake system (znuGHI), three TonB-dependent receptors (znuK, znuL and znuM) and one new putative transporter of a family not yet characterized (zrpW). Zur is also directly involved in the activation of a RND and a P-type ATPase efflux systems, as revealed by beta-galactosidase and site-directed mutagenesis assays. Several genes belonging to the Fur regulon were also downregulated in the zur mutant, suggesting a putative cross-talk between Zur and Fur regulatory networks. Interestingly, a phenotypic analysis of the znuK and znuL mutants has shown that these genes are essential for growth under zinc starvation, suggesting that C. crescentus uses these TonB-dependent outer membrane transporters as key zinc scavenging systems. Conclusions: The characterization of the C. crescentus Zur regulon showed that this regulator coordinates not only uptake, but also the extrusion of zinc. The uptake of zinc by C. crescentus in conditions of scarcity of this metal is highly dependent on TonB-dependent receptors, and the extrusion is mediated by an RND and P-type ATPase transport systems. The absence of Zur causes a disturbance in the dynamic equilibrium of zinc intracellular concentration, which in turn can interfere with other regulatory networks as seen for the Fur regulon. (AU) | |
| FAPESP's process: | 11/18847-4 - Identification of genes regulated in response to zinc starvation in Caulobacter crescentus |
| Grantee: | Ricardo Ruiz Mazzon |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |