一个结构上不同的ATP依赖的腺基胺依赖的氨酸5,6-氨基酶的ATP依赖的活性化因子的表征
Amanda L Darbyshire1, Kirsten R Wolthers1
1Department of Chemistry, University of British Columbia, Okanagan Campus, 3247 University Way, Kelowna V1V 1V7, Canada.
Biochemistry
|March 12, 2024
概括
研究人员发现了KamB和KamC,这些蛋白质可以重新激活B12依赖的酶氨酸5,6-氨基突变酶 (5,6-LAM). 这一发现对于了解细菌如何维持参与新陈代谢的必需B12酶的活性至关重要.
科学领域:
- 生物化学 生物化学
- 微生物学 微生物学
- 酶学 是一种酶学.
背景情况:
- 像*Fusobacterium nucleatum*这样的无氧细菌使用素5,6-氨基突酶 (5,6-LAM) 来发酵素.
- 5,6-LAM是一种依赖于氨酸5'-酸盐 (PLP) 的酶,对氨酸代谢至关重要.
- 依赖AdoCbl的酶,包括5,6-LAM,容易无活化,导致酶活性丧失.
研究的目的:
- 为了识别负责激活不活化的5,6-LAM酶的基因.
- 描述已识别的反激活蛋白的功能和机制.
主要方法:
- 在大肠杆菌中发现的基因 (*kamB*和*kamC*) 的同时表达和蛋白质净化.
- 酶活性测定,包括ATP-化活性和合紫外线可见光谱测定.
- 在无氧条件下进行光谱学研究 (UV-vis) 来分析中间度和活性化机制.
主要成果:
- 鉴定了编码KamB和KamC蛋白的*kamB*和*kamC*基因,这些基因共同净化并表现出依赖ATP的活性.
- 卡姆BC通过将损坏的氧 (III) 胺换成AdoCbl来重新激活5,6-LAM,从而增加了 (II) 胺中间体.
- 卡姆BC对5,6-LAM表现出特异性,但对相关的4-5-氨基突变酶没有影响.
结论:
- 卡姆B和卡姆C形成了一个新的ATP-依赖的5,6-LAM的活性化系统,与已知的B12伴侣不同.
- 这个系统维持了B12依赖酶的细胞活性,这对细菌新陈代谢至关重要.
- 这一发现扩大了对蛋白质机械的理解,这些机械是为了支持可巴胺酶的功能而进化而来的.
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