Zn(II) metallochaperones in E. coli

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DESCRIPTION (provided by applicant): The long-term goal of this project is to understand Zn(ll) trafficking in cells. The main goal of this study is to identify Zn(ll)-metallochaperones in E. coli involved specifically with Zn(ll) import and transport. Specifically, we propose to identify the putative, soluble Zn(ll)-metallochaperones that are thought to deliver Zn(ll) from outer membrane-bound channels/porins to the ribosomes and/or proteins. We propose to utilize the following strategy to achieve our goals. DNA microarrays were used to identify five transcripts (of Zn(ll)-metallochaperone candidates) that were up-regulated in E. coli cells stressed with Zn(ll) deficiency. (1) These five candidate proteins will be over-expressed, purified, and characterized for structure and Zn(ll) binding. (2) All candidates that bind Zn(ll) will be used in pulldown experiments in an effort to identify any proteins that form complexes with the candidates. In addition, E. coli cells lacking the Zn(ll) binding candidates (knockout lines) will be obtained. (3) All proteins identified in the pulldown experiments will be over-expressed, purified, and characterized for Zn(ll) binding and structure. Polyclonal antibodies against these proteins will be generated. (4) Wild-type and mutant E. coli cells will be cultured in the presence of 65Zn, and the resulting soluble proteins will be subjected to native gel electrophoresis. The gels will be analyzed for differential amounts of 65Zn, and western blots of the gels will be analyzed using the aforementioned polyclonal antibodies. The knockout lines will also be assayed for Zn(ll) transport by using a recently developed assay in the lab. Since Zn(ll) is an essential metal ion for bacteria and metallochaperones deliver metal ions to specific proteins, we believe that understanding Zn(ll)-transport in E. coli will present novel protein targets for the design and preparation of a new class of antibiotics. The need for new classes of antibiotics is particularly important currently to combat the clinical crisis of antibiotic resistance and to combat the Category A and B bacterial strains on the CDC's bioterrorism watch list.