Molecular Characterization of AtCam9

AtCam9 的分子表征

• 批准号: 0446260
• 负责人: Raymond Zielinski
• 金额: --
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0446260&HistoricalAwards=false
• 关键词: Molecular; Characterization; AtCam9

Project Abstract Calcium ions (Ca2+) are used as messengers in all eukaryotic cells to trigger physiological responses to internal and external stimuli, such as hormones and environmental stresses. The initial perception of Ca2+ is accomplished by proteins that specifically bind the metal and in turn modulate the activities of other cellular proteins. The best characterized example of this class of proteins is calmodulin (Cam). Cam proteins have long been implicated in regulating plant growth and development as well as responses of plants to stressful stimuli, but the specific mechanisms by which they participate in these responses are not well understood. This proposal focuses on defining the role of ATCam9, a novel member of the AtCam gene family of Ca2+-binding proteins in Arabidopsis. Preliminary data have revealed that AtCam9 might function by a mechanism similar to, but not identical with, more conventional Cam proteins. This suggests that AtCam9 functions by interacting with and regulating a unique set of proteins. In addition, knockout mutants of AtCam9 display a rapid growth/overall enlarged phenotype compared with control Arabidopsis plants; knockouts of conventional Cam genes yield plants with reduced growth phenotypes. Thus, AtCam9 appears to function in a manner distinct from conventional Cam proteins on both the molecular and organismic levels. The hypothesis that will be tested in this proposal is whether AtCam9 functions as a negative regulator of the rate of plant growth. To test this model and define the pathway(s) by which AtCam9 modulates growth, the project will pursue four specific aims:(1) It will be determined whether AtCam9 regulates growth by modulating cell expansion or whether it also plays a role in cell division. (2) It will be determined whether conventional AtCam proteins can substitute for AtCam9, and conversely, whether AtCam9 can substitute for conventional Cam proteins. (3) The cell types and subcellular locations in which AtCam9 is expressed will be defined. As part of this aim, it will be determined whether AtCam9 is freely diffusible, a property that will indicate whether AtCam9 functions by interacting with other proteins. (4) The identities of AtCam9-interacting proteins will be determined, and the timing and subcellular locations of the interactions with AtCam9 will be defined.Broader Impact of the Proposed Activity. Elucidating the specific functions mediated by AtCam9 will provide a deeper understanding of the roles of Ca2+ in regulating plant growth and development, factors that are central to agricultural productivity. Understanding the molecular bases for the unexpected phenotype displayed by AtCam9 knockout plants may facilitate novel strategies for engineering or controlling plant growth. The project will provide training for students from the undergraduate through the postdoctoral levels in protein biochemistry, Arabidopsis molecular genetics, analyses of plant growth and cellular imaging.

钙离子（Ca 2+）在所有真核细胞中被用作信使，以触发对内部和外部刺激（如激素和环境压力）的生理反应。 Ca 2+的初始感知是由特异性结合金属的蛋白质完成的，反过来又调节其他细胞蛋白质的活性。 这类蛋白质的最佳表征实例是钙调蛋白（Cam）。 CAM蛋白长期以来一直参与调节植物的生长和发育以及植物对胁迫刺激的反应，但它们参与这些反应的具体机制尚不清楚。 该提案的重点是定义ATCam 9的作用，ATCam 9是拟南芥中AtCam基因家族的Ca 2+结合蛋白的新成员。 初步数据显示，AtCam 9可能通过与更传统的Cam蛋白类似但不相同的机制发挥作用。 这表明AtCam 9通过与一组独特的蛋白质相互作用并调节其功能。 此外，AtCam 9的敲除突变体与对照拟南芥植物相比显示出快速生长/整体扩大的表型;常规Cam基因的敲除产生具有降低的生长表型的植物。 因此，AtCam 9似乎在分子和器官水平上以不同于常规Cam蛋白的方式起作用。 在本提案中将测试的假设是AtCam 9是否作为植物生长速率的负调节剂起作用。 为了测试该模型并确定AtCam 9调节生长的途径，该项目将追求四个具体目标：（1）将确定AtCam 9是否通过调节细胞扩增来调节生长，或者它是否也在细胞分裂中发挥作用。 (2)将确定常规AtCam蛋白是否可以替代AtCam 9，并且相反地，AtCam 9是否可以替代常规Cam蛋白。(3)将定义AtCam 9表达的细胞类型和亚细胞位置。 作为这一目标的一部分，将确定AtCam 9是否是自由扩散的，这一特性将表明AtCam 9是否通过与其他蛋白质相互作用发挥功能。 (4)将确定AtCam 9相互作用蛋白的身份，并确定与AtCam 9相互作用的时间和亚细胞位置。 阐明AtCam 9介导的特定功能将使人们更深入地了解Ca 2+在调节植物生长和发育中的作用，这些因素对农业生产力至关重要。 了解AtCam 9基因敲除植物所表现出的意想不到的表型的分子基础可能有助于工程或控制植物生长的新策略。 该项目将为学生提供蛋白质生物化学，拟南芥分子遗传学，植物生长和细胞成像分析的本科到博士后水平的培训。