Collaborative Research: Antarctic Diatom Proteorhodopsins: Characterization and a Potential Role in the Iron-limitation Response

合作研究：南极硅藻蛋白视紫红质：特征及其在铁限制反应中的潜在作用

• 批准号: 1745036
• 负责人: Adrian Marchetti
• 金额: $ 51.13万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1745036&HistoricalAwards=false
• 关键词: Collaborative; Research; Antarctic; Diatom; Proteorhodopsins

Proteorhodopsins are proteins that are embedded in membranes that can act as light-driven proton pumps to generate energy for metabolism and growth. The discovery of proteorhodopsins in many diverse marine prokaryotic microbes has initiated extensive investigation into their distributions and functional roles. Recently, a proton-pumping, rhodopsin-like gene was identified in diatoms, a group of marine phytoplankton that dominates the base of the food web in much of the Southern Ocean. Since this time, proteorhodopsins have been identified in many, but not all, diatom species. The proteorhodopsin gene is more frequently found in diatoms residing in cold, iron-limited regions of the ocean, including the Southern Ocean, than in diatoms from other regions. It is thought that proteorhodopsin is especially suited for use energy production in the Southern Ocean since it uses no iron and its reaction rate is insensitive to temperature (unlike conventional photosynthesis). The overall objective of the project is to characterize Antarctic diatom-proteorhodopsin and determine its role in the adaptation of these diatoms to low iron concentrations and extremely low temperatures found in Antarctic waters. This research will provide new information on the genetic underpinnings that contribute to the success of diatoms in the Southern Ocean and how this unique molecule may play a pivotal role in providing energy to the base of the Antarctic food web. Broader impact activities are aimed to promote the teaching and learning of polar marine-sciences related topics by translating research objectives into readily accessible educational materials for middle-school students.This project will combine molecular, biochemical and physiological measurements to determine the role and importance of proteorhodopsin in diatom isolates from the Western Antarctic Peninsula region. Proton-pumping characteristics and pumping rates of proteorhodopsin as a function of light intensity and temperature, the resultant proteorhodopsin-linked intracellular ATP production rates, and the cellular localization of the protein will be determined. The project will examine the environmental conditions where Antarctic diatom-proteorhodopsin is most highly expressed and construct a cellular energy budget that includes diatom-proteorhodopsin when grown under these different environmental conditions. Estimates of the energy flux generated by proteorhodopsin will be compared to total energy generation by the photosynthetic light reactions and metabolically coupled respiration rates. Finally, the characteristics and gene expression of diatom-proteorhodopsin in Antarctic diatoms and a proteorhodopsin-containing diatom isolates from temperate regions will be compared in order to determine if there is a preferential dependence on energy production through proteorhodopsin in diatoms residing in cold, iron-limited regions of the ocean. Educational activities will be performed in collaboration with the Morehead Planetarium and Science Center who co-ordinates the SciVentures program, a popular summer camp for middle-school students from Chapel Hill and surrounding areas. In collaboration with the Planetarium, the researchers will develop activities that focus on phytoplankton and the important role they play within polar marine food webs for the SciVentures participants. Additionally, a teaching module on Antarctic phytoplankton will be developed for classrooms and made available to educational networking websites and presented at workshops for science educators nationwide.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

蛋白质视紫质是嵌入在膜中的蛋白质，可以作为光驱动的质子泵，为新陈代谢和生长产生能量。蛋白视紫红质在多种海洋原核生物中的发现，引发了对其分布和功能作用的广泛研究。最近，在硅藻中发现了一种类似于视紫红质的质子泵送基因。硅藻是一种海洋浮游植物，在南大洋大部分地区的食物链中占据主导地位。从那时起，蛋白视紫红质已经在许多但不是所有的硅藻物种中被鉴定出来。蛋白视紫红质基因在居住在寒冷、铁有限的海洋区域(包括南大洋)的硅藻中比在其他地区的硅藻中更常见。蛋白视紫红质被认为特别适合在南大洋利用能源生产，因为它不使用铁，其反应速度对温度不敏感(与传统的光合作用不同)。该项目的总体目标是描述南极硅藻--蛋白视紫红质的特征，并确定其在使这些硅藻适应南极水域中低铁浓度和极低温度方面的作用。这项研究将提供新的信息，说明促成南大洋硅藻成功的遗传基础，以及这种独特的分子如何在为南极食物网的基础提供能量方面发挥关键作用。更广泛的影响活动旨在通过将研究目标转化为中学生容易获得的教材，促进与极地海洋科学有关的专题的教和学。该项目将结合分子、生物化学和生理测量，以确定蛋白视紫红质在南极半岛西部地区硅藻分离中的作用和重要性。蛋白视紫红质的质子泵浦特性和泵浦速率作为光强度和温度的函数，由此产生的蛋白视紫红质连接的细胞内ATP的产生速率，以及蛋白质的细胞定位将被确定。该项目将研究南极硅藻蛋白紫质最高表达的环境条件，并建立一个细胞能量收支，其中包括在这些不同环境条件下生长的硅藻蛋白紫质。对蛋白视紫红质产生的能量通量的估计将与光合作用光反应和代谢耦合呼吸速率产生的总能量进行比较。最后，将比较南极硅藻和温带地区分离的含有蛋白紫质的硅藻中蛋白紫质的特征和基因表达，以确定居住在寒冷、铁有限的海洋区域的硅藻是否优先依赖蛋白紫质产生能量。教育活动将与莫尔黑德天文馆和科学中心合作进行，后者负责协调本项目，这是一个受教堂山及其周边地区中学生欢迎的夏令营。与天文馆合作，研究人员将开展活动，重点关注浮游植物及其在极地海洋食物网中为本风险投资参与者所发挥的重要作用。此外，还将为课堂开发一个关于南极浮游植物的教学模块，并提供给教育网络网站，并在全国科学教育工作者的研讨会上介绍。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Low diversity of a key phytoplankton group along the West Antarctic Peninsula

• DOI: 10.1002/lno.11765
• 发表时间: 2021-05-06
• 期刊: LIMNOLOGY AND OCEANOGRAPHY
• 影响因子: 4.5
• 作者: Brown, Michael S.;Bowman, Jeff S.;Schofield, Oscar M.
• 通讯作者: Schofield, Oscar M.

Interactive effects of iron and light limitation on the molecular physiology of the Southern Ocean diatom Fragilariopsis kerguelensis

铁和光限制对南大洋硅藻 Fragilariopsisäkerguelensis 分子生理学的相互作用影响

• DOI: 10.1002/lno.11404
• 发表时间: 2020
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Moreno, Carly M.;Gong, Weida;Cohen, Natalie R.;DeLong, Kimberly;Marchetti, Adrian
• 通讯作者: Marchetti, Adrian