通过两种直接相互作用的GTP酶对GTP水解的相互刺激
1Department of Biochemistry and Biophysics, University of California Medical School, San Francisco 94143-0448, USA.
概括
大肠杆菌蛋白Ffh和FtsY是细菌血膜的向蛋白. 一项研究表明,它们的GTP水解是相互合的,这表明它们在蛋白质向中相互调节.
科学领域:
- 分子生物学分子生物学
- 细菌生理学 细菌生理学
- 蛋白质向定位是指蛋白质向定位.
背景情况:
- 大肠杆菌的关三酸盐 (GTP) 结合蛋白Ffh和FtsY参与了对细菌血膜的共同翻译蛋白的向.
- 它们的相互作用和核酸水解的精确机制仍在研究中.
研究的目的:
- 研究Ffh和FtsY在大肠杆菌中的核酸特异性和相互作用.
- 阐明Ffh-FtsY系统中GTP水解的机制.
主要方法:
- 用于改变FtsY的核酸特异性,从GTP转变为三酸桑托辛 (XTP) 的局部导向突变发生.
- 使用纯化的Ffh-4.5S核蛋白和野生型或突变FtsY蛋白进行了核酸水解试验.
- 评估了在水解反应中对特定核酸 (GTP或XTP) 的要求.
主要成果:
- 当XTP存在时,XTP特异的突变FtsY通过Ffh-4.5S核糖蛋白刺激了GTP水解.
- 需要Ffh-4.5S核糖蛋白和GTP来通过突变FtsY.进行XTP的水解.
- 这些结果表明,在核酸三酸盐水解中,Ffh和FtsY之间存在相互合.
结论:
- 通过Ffh和FtsY进行核酸三酸盐水解发生在相互合的反应中.
- 在蛋白向途径中,Ffh和FtsY可能作为相互调节蛋白发挥作用.
- 这种相互调节确保了有效和协调的蛋白质输送到细菌的血膜.
相关概念视频
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...


