PUTATIVE OUTER MEMBRANE IRON/SIDEROPHORE RECEPTOR (YIUR)

Brookhaven Science Assoc-Brookhaven Lab, Upton NY

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Overview We are currently working on obtaining the crystal structure of several outer membrane proteins from Y.pestis. The structures will give insights into bacterial iron transport mechanisms as well as potentially yield information for the development of a plague vaccine and diagnostic tools. Structural studies of membrane proteins often have inherent problems at all stages of the process including expression, purification, crystallisation and diffraction. However to maximise the success of this study we are working on several targets in parallel. So far, we have successfully expressed, purified and crystallised three distinct proteins two sharing low homology and one non-homologous protein. Additionally the Buchanan laboratory already has a very good history of successfully solving membrane protein structures. We are now at the stage of the project where we need to screen a lot of crystals for good diffraction. As with all membrane protein crystals there might be a lower useful diffraction to crystal ratio but on th upside the impact of the structure(s) will be greater than for most soluble proteins. It is expected that this project will greatly benefit from high throughput diffraction screening methods (automounter) to identify rare well difracting crystals. YiuR Iron is an essential component of many enzymes required for growth and metabolism of bacteria In aerobic environments at physiological pH, iron exists predominantly as oxidized ferric iron, Fe(III), which forms insoluble hydroxides. In order to acquire iron under these conditions, gram-negative bacteria like Y.pestis usually produce and release high-affinity ferric iron-binding compounds (called siderophores), which capture iron from the environment. The protein target described on this form is a putative outer membrane iron/siderophore receptor and could be responsible for the transport of iron into the periplasm. YiuR is a tonB type receptor protein predicted to consist of a 22 stranded Beta barrel spanning the membrane and a plug domain blocking the pore of the barrel.