28/08/2023
[What is Biobrick]
在上一篇介紹合成生物學的貼文中,有提到讓細菌生產胰島素這個例子,其中將胰島素的基因插入質體的過程,就可以運用到Biobrick的概念,那甚麼是Biobrick呢?從文字上解讀就是Bio + brick所以就是將生物的基因依照功能分成不同部件,然後像積木一樣組裝在一起以後變成一段有功能的基因序列,我們稱那一段基因序列為Biobrick。
Biobrick最主要的零件有四個:啟動子、核醣體結合位點、目標基因、終止子。啟動子的功能是,當接收到訊號以後會開始驅動基因表現。核糖體結合位點的功能是讓核糖體附著上去。目標基因是我們想要細菌合成的蛋白質DNA序列。終止子中會有富含GC的hairpin,破壞 mRNA-DNA-RNA聚合酶三元複合物,以此終止RNA聚合酶繼續轉錄,起到介導轉錄終止的作用,並讓轉錄好的RNA離開RNA聚合酶複合物。而這些零件都有符合限制酶組裝的標準,可以有相同的剪切位便於將這些零件組裝在一起,達到可以方便替換、模組化的效果。
那麼前面提到的讓細菌產生胰島素的例子中,插入到質體中的Biobrick就大致會有上述提到的四個零件。大致上的程序會是這樣,啟動子接收到訊號以後,開始轉錄胰島素的基因,終止子停止轉錄並釋放轉錄好的RNA後,核醣體結合到核醣體結合位點上,開始轉譯,最後得到我們的蛋白質 — 胰島素。
In the previous post about synthetic biology, we mentioned the example of using bacteria to produce insulin. This involves the process of inserting the insulin gene into a plasmid, which can utilize Biobrick. So, what is Biobrick? Literally interpreted, it's a combination of "Bio" and "brick." This concept aims to divide biological genes into functional parts, similar to assembling puzzles. Once these parts are assembled, they form a functional gene sequence, which we refer to as a Biobrick.
Biobrick consists of four main parts: promoter, ribosome binding site(RBS), target gene, and terminator. The promoter is to initiate gene expression upon receiving a signal. The RBS helps attach ribosomes. The target gene is the DNA sequence of the protein we want bacteria to synthesize. The terminator has GC-rich hairpin structure, which disrupts the mRNA-DNA-RNA polymerase ternary complex and leads to the termination of transcription. This process facilitates transcription termination, allowing the transcript RNA to separate from the RNA polymerase complex. These parts meet standard restriction enzyme assembly, allowing them to be easily assembled together for modularity and interchangeability.
In the case of bacteria producing insulin, the Biobrick inserted into the plasmid would generally include these four mentioned parts. The procedure involves the promoter receiving a signal, initiating the transcription of the insulin gene. The terminator halts transcription and releases the transcript RNA. The ribosome binds to the RBS, initiating translation, ultimately producing the protein — insulin.