对一种细菌腺索基巴胺依赖突变酶的G蛋白伴侣介导成熟的结构洞察
Francesca A Vaccaro1, Daphne A Faber2, Gisele A Andree1
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
The Journal of biological chemistry
|July 30, 2023
概括
像ICMF这样的G蛋白辅助体使用GTP水解来成熟金属酶,通过输送腺可巴胺 (AdoCbl) 或去除损坏的可巴胺 (Cbl). 这一过程涉及ICMF寡合化和构造变化,从而打开突变酶活性部位.
科学领域:
- 生物化学 生化学
- 分子生物学分子生物学
- 酶学 是一种酶学.
背景情况:
- 对于金属酶的成熟来说,G蛋白伴侣是至关重要的.
- 人类的MMAA和细菌的MeaB将腺可巴胺 (AdoCbl) 传递给甲基-CoA突变酶.
- 异布基-CoA突变酶化 (IcmF) 呈现了一个与其位突变酶相关联的G蛋白域.
研究的目的:
- 为了调查其他G蛋白伴侣是否采用先前在MeaB.中观察到的活性构造.
- 为了阐明G蛋白辅助的AdoCbl依赖突变酶成熟的分子机制,在化的ICMF系统中.
主要方法:
- 使用质量光度和电子显微镜 (EM) 的寡合化研究.
- 电子显微镜 (Cryo-EM) 用于高分辨率的结构分析.
- 生物化学试验研究GTP水解和辅因子结合.
主要成果:
- 在ICMF中的G蛋白域在寡合化后形成一个活性构造,类似于MeaB.
- 在应对可胺 (Cbl) 损伤和非水解性GTP类似物时,ICMF进行寡合.
- 低温电磁显示,第二个ICMF原体,使用交换机III残留物,开突变酶活性位点进行辅因子交换.
结论:
- 结合GTP将突变酶用于辅因子的递送,而GTP水解则促进辅因子的捕获.
- 这项研究揭示了AdoCbl依赖突变酶的G蛋白中介成熟的分子基础.
- 这项工作阐明了G蛋白伴侣在辅因子递送和修复途径中的机制.
相关概念视频
Bacterial Protein Maturation
36
Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...
36
Molecular Chaperones and Protein Folding
18.0K
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
The...
18.0K
Activation and Inactivation of G Proteins
7.3K
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...
7.3K
GPCRs Regulate Adenylyl Cylase Activity
5.7K
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...
5.7K
Coat Assembly and GTPases
3.6K
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
3.6K
Cooperative Allosteric Transitions
7.9K
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
7.9K


