BRIGE: Proposal to Study Self-Assembling Siderophore Vesicles

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“PI: Richards, abigail”提案号：0927109“智力优势：表面活性剂分子具有改变界面特征和现象的能力。该提案将资助研究生物表面活性剂铁载体（sodachelins）对胶束和囊泡形成的影响条件，以及确定这些囊泡在各种条件下形成后的稳定性。钠铁蛋白是一组由钠湖细菌分离物分泌的新型两亲性铁载体（铁螯合分子）。直到最近，大多数涉及铁载体生产的研究都集中在致病微生物或居住在非极端环境中的微生物上。在过去的十年中，对海洋微生物的研究导致了一些新的铁载体的发现，这些铁载体具有紫外线诱导的铁还原、胶束形成和铁诱导的囊泡形成等新特性。对钠链蛋白的深入研究将进一步阐明控制胶束向囊泡转变的因素。钠磷脂铁载体由一个肽性的铁螯合头基团组成，附加在一系列不同碳长度（C10至C14）和不饱和水平的不同脂肪酸尾部。小红蛋白在结构上与其他已知的由海洋细菌产生的两亲性铁载体非常相似，据报道，这些铁载体可以形成胶束，可以自组装成囊泡，形成200纳米量级的小纳米球体。这种自组装是由添加多余的铁触发的，超出了铁螯合头组的协调，产生了一个富含铁表面的球形结构。由于与这些分子在结构上的相似性，人们推测这些分子也会以类似的机制形成胶束和囊泡。建议的工作涉及和分析有利于小泡形成的条件，以及可能促进小泡受控分解的机制。本文将研究两种分解方法。由于先前发现小钠磷脂经历紫外线诱导的光解，因此假设紫外线暴露可以触发囊泡的受控分解。本研究中要测试的囊泡分解的第二个可能机制是通过强金属螯合剂去除囊泡外表面的铁。被外壳配位的铁被认为具有较低的亲和性，并且在引入另一种金属螯合剂时很容易被去除，从而诱导囊泡结构的分解。对囊泡形成和破坏的控制研究可能会导致生物杀灭剂应用和药物输送系统的未来发展。更广泛的影响：所提出的工作将为PI未来在杀菌剂输送应用和流动条件下剪切应力下囊泡稳定性的研究奠定基础。虽然这主要是一项研究计划，但第二项更重要的成果是扩大未被充分代表的群体在科学和工程领域的参与。这位私家侦探自己也是一名年轻的研究员，这是她第一次获得终身职位，她为研究生和本科生的支持都做了预算。一名美国印第安女本科生目前在PI担任本科生研究助理，并将在未来获得该项目的资助。PI和这名本科生将访问蒙大拿部落学院，介绍科学和工程职业的经验和机会。一名西班牙裔美国博士生也被确定来进行其中概述的大部分研究，并将有助于增加少数民族在博士水平上作为榜样的人数。该提案还为当地高中生提供了机会，让他们在夏季与PI一起完成部分拟议的研究。最后，PI将在科学会议、同行评议的期刊文章和肥皂湖保护协会上积极传播通过这项工作取得的进展。这是一个两年一次的科学研讨会，向居住在湖边的非专业农村社区成员介绍有关肥皂湖的研究。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."PI: Richards, AbigailProposal Number: 0927109Intellectual Merit: Surfactant molecules have the ability to alter interfacial characteristics and phenomena. This proposal will fund an investigation into the conditions affecting both micelle and vesicle formation by biosurfactant siderophores, the sodachelins, as well as determine the stability of these vesicles in a variety of conditions, once formed. The sodachelins are a group of novel amphiphilic siderophores (iron chelating molecules) secreted by a soda lake bacterial isolate. Until recently, most research involving siderophore production has focused on pathogenic microbes or those inhabiting non-extreme environments. Over the past decade, studies focused on marine microbes resulted in the discovery of several new siderophores with novel traits such as UV-induced iron reduction, micelle formation and ironinduced vesicle formation. An in depth study of the sodachelins will further elucidate factors governing micelle to vesicle transitions. The sodachelin siderophores consist of a peptidic, iron-chelating head group appended to a series of different fatty acid tails of various carbon length (C10 to C14) and level of unsaturation. The sodachelins are very similar in structure to other known amphiphilic siderophores, produced by marine bacteria, which are reported to form micelles that can self-assemble into vesicles, forming small nano-spheres on the order of 200nm. This self-assembly is triggered by the addition of excess iron, beyond what is already coordinated by the iron chelating head group, generating a spherical structure with iron rich surfaces. Because of structural similarities of the sodachelins to these molecules, it is hypothesized that the sodachelins will also form micelles and vesicles in a similar mechanism. Proposed work involves and analysis of the conditions favoring vesicle formation by the sodachelins, as well as mechanisms that may facilitate a controlled disaggregation of the vesicles. Two methods of disaggregation will be studied. Because the sodachelins were previously found to undergo a UV-induced photolysis it is postulated that UV exposure could trigger a controlled disassembly of the vesicles. A second possible mechanism of vesicle disassembly to be tested in this research is the removal of the iron coordinated on the outer vesicle surface by a strong metal chelator. The iron coordinated by the outer shell is thought to be coordinated with lower affinity and may be easily removed upon the introduction of another metal chelator, inducing the disaggregation of the vesicle structure. The study of the controlled formation and disruption of the vesicles may lead to future advances in biocide applications and drug delivery systems.Broader Impacts: The work proposed will lay the foundation for future investigations by the PI in biocide delivery applications and investigations of vesicle stability under shear stress in flow conditions. While this is primarily a research proposal, a second, but more important deliverable is to broaden the participation of underrepresented groups in science and engineering. The PI, herself a young investigator in her first tenure track appointment has budgeted for both graduate and undergraduate student support. A female American Indian undergraduate student is currently working for the PI as an undergraduate research assistant and will be funded in the future on this project. The PI and this undergraduate will visit Montana Tribal colleges to present experiences and opportunities available in science and engineering careers. A Hispanic American doctoral student has also been identified to conduct much of the research outlined within and will serve to increase the number of minorities serving as role models at the doctoral level. Also provided in this proposal are opportunities are for local high school students to work with the PI on a portion of this proposed research during the summer. Finally, the PI will actively disseminate advancements made through this work at scientific meetings, peer reviewed journal articles and the Soap Lake Conservancy?s Science Symposia which is a bi-annual presentation of research involving Soap Lake delivered to the lay, rural community-members living near the lake.