Mechanism of Intrinsic Hydrolysis in Small GTPases

智力价值小GTP酶的超家族包括五组不同的蛋白质，它们共同涉及细胞功能的几乎所有方面。当它们与鸟苷二磷酸(GDP)结合时是不活跃的，当与三磷酸形式(GTP)结合时是功能活跃的。GTP酶已经被很好地研究了25年，调节它们的一般机制被广泛接受，以至于它经常出现在生物化学和细胞生物学的教科书中。该项目基于一个范式转换假说，在特定情况下修改了一些GTP酶的这一机制，阐明了与不同形式的GTP结合蛋白相关的微妙水平的调控。在该项目下进行的研究集中在Ras GTP酶作为一个模型，用于阐明其功能在新发现的背景下失活的化学机制，在第二个GTP酶上测试该机制，并使用计算方法来查看整个家族的序列模式，挖掘GTP酶结构的数据库，以评估最近在NSF支持下发现的调控机制的一般性。这个项目将使用多学科方法，重点是X射线结晶学、中子结晶学、量子力学/分子力学计算(QM/MM)、动力学实验和跨GTP酶超家族的结晶水分析，使用我们与先前NSF基金开发的内部程序相关溶剂位置检测(Drop)。广泛影响该项目支持三名研究生，他们将在蓬勃发展和多样化的研究和教育环境中接受培训，在这种环境中，指导是团队在所有级别的学术阶梯上团队合作的重要方面。每个人都将在这个项目上与一名本科生密切合作并指导他们。本科生是研究的组成部分，他们参与了Co-op项目，该项目支持东北地区的本科生在实验室长期全职工作。PI正在通过东北教师研讨会计划与少数族裔服务机构发展强大的联盟，该计划是她到达东北后发起的。其目标是增加化学生物学博士项目的申请者的多样性，同时让少数族裔学生参与令人兴奋的研究，以促进对科学的长期承诺。通过与优质少数群体教育(QEM)网络的伙伴关系，非政府组织正在向没有研究机会的少数群体服务机构的本科生提供帮助。在项目期间，两名少数民族本科生将获得暑期研究资助。每个项目都将有一名研究生导师，并将与PI密切合作，以确保实验室的有效学习和生产力。

Intellectual MeritThe superfamily of small GTPases includes five distinct groups of proteins that collectively touch on virtually all aspects of cellular function. They are inactive when bound to guanosine diphosphate (GDP) and functionally active when bound to the triphosphate form (GTP). GTPases have been very well studied for over 25 years and a general mechanism through which they are regulated is so well accepted that it routinely appears in Biochemistry and Cell Biology texts books. This project is based on a paradigm-shifting hypothesis that modifies this mechanism for some GTPases under particular circumstances, elucidating a subtle level of regulation associated with different forms of the GTP-bound protein. The research performed under this project focuses on Ras GTPase as a model for elucidating the chemical mechanism through which its function is deactivated in the newly discovered context, tests the mechanism on a second GTPase and uses computational approaches to look at sequence patterns across the family, mining the database of GTPase structures to assess the generality of the regulatory mechanism recently uncovered with aid from previous NSF support. This project will use multidisciplinary approaches focused on X-ray crystallography, neutron crystallography, quantum mechanics/molecular mechanics calculations (QM/MM), kinetic experiments and a crystallographic water analysis across the superfamily of GTPases using our in-house program Detection of Related Solvent Positions (DRoP) developed with previous NSF funding.Broader ImpactThe project supports three graduate students who will be trained in a thriving and diverse research and educational environment where mentoring is an important aspect of teamwork in the group at all levels of the academic ladder. Each will work closely with and mentor an undergraduate student on the project. Undergraduates constitute and integral part of the research, engaged in the Co-op program that supports Northeastern undergraduates for extended period of full time in the laboratory. The PI is developing strong alliances with minority serving institutions through the Northeastern Faculty Seminar Program, which she has initiated since arriving at Northeastern. The goal is to increase the diversity of applicants to the Ph.D. program in Chemical Biology while engaging minority students in exciting research that will promote long-term commitment to science. Through a partnership with Quality Education for Minorities (QEM) network the PI is reaching out to undergraduates from minority-serving institutions that do not have research opportunities. Two minority undergraduate students will be supported for summer research during the duration of the project. Each will have a graduate student mentor on the project and will work closely with the PI to assure effective learning and productivity in the laboratory.