Regulating Microtubule Severing Physically and Chemically

物理和化学调控微管切断

• 批准号: 10797126
• 负责人: JENNIFER L ROSS
• 金额: $ 7.25万
• 依托单位: SYRACUSE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10797126
• 关键词: Binding; Biochemistry; Biological Assay; Brain; Cell division; Cell physiology; Cells; Chemicals; Code; Cytoskeleton; Data; Defect; Development; Dimerization; Enzymes; Family; Filament; Fluorescence Microscopy; Genetic Recombination; Goals; Human body; In Vitro; Light; Link; Location; Microtubule Polymerization; Microtubule-Associated Proteins; Microtubules; Phosphorylation; Regulation; Research Personnel; Scheme; Serine; Tail; Techniques; Testing; Time; Tubulin; Work; cell motility; ciliopathy; density; dimer; katanin; neuron development; novel; proteostasis; reconstitution; repaired; single molecule; small molecule inhibitor; tool

PROJECT SUMMARY The goal of this new proposal application is to uncover the physical and chemical regulatory schemes to control the microtubule severing enzyme, katanin. Katanin is a AAA+ enzyme that hexamerizes in order to remove tubulin dimers from the microtubule filament resulting in filament severing. When at high levels, and unregulated in cells, katanin can destroy the entire microtubule network, thus turning it off is an essential control knob. Overactivity of katanin can lead to complete loss of microtubule polymer, but underactivity is linked with developmental defects in the brain and ciliopathies. The central hypothesis of the proposed work is that the mechanisms to control katanin actually regulate katanin hexamer oligomerization. Our prior work indicated that oligomerization is the a rate-limiting step for katanin. We seek to use quantitative fluorescence microscopy to directly test the hypothesis that oligomerization controls severing through physical and chemical means. Specifically, we will explore the regulation of katanin concentration in live cells using a novel light-sensitive dimerization domain to drive katanin concentration locally by exploring the following aims: (1) Quantification of both the katanin concentration and the microtubule filament density as a function of time will enable biochemistry in the cell for the first time for katanin. (2) Using in vitro reconstitution of microtubule severing and a novel single molecule counting technique, we will examine the effect of the phosphorylation state of serine 131 on binding, oligomerization, and severing by katanin. (3) The tubulin carboxy-terminal tail has been shown to act as a code to control many microtubule-associated proteins and enzymes. Severing enzymes are no different and are known to require the carboxy- terminal tail to sever microtubules. Our preliminary data shows that katanin’s regulation is distinct from other severing enzymes. We will use a severing inhibition assay and single molecule counting to quantify the ability to katanin to bind and act on microtubules of various carboxy-terminal tail sequences. Accomplishing the proposed aims will create a novel microtubule disruption tool that could be used in a variety of cellular and organismal assays to control the location and density of the microtubule network. Further, the proposed studies will reveal new information on how microtubule severing can be regulated in cells through controlling the katanin oligomerization state. This crucial step for katanin activity may be an entry-point for creating small molecule inhibitors for microtubule severing enzymes and other AAA+ enzymes that are important for a host of essential cellular functions including protein homeostasis, DNA recombination, replication, and repair.

项目总结