拉斯帕托霉素C及其相似物與受質結合特性之研究

Abstract

拉斯帕托霉素C (Laspartomycin C, LspC) 是被最廣泛研究的鈣依賴型抗生素 (Calcium-dependent antibiotic, CDA)之一。在之前已有關於LspC的晶體研究，在研究中已經證實了LspC能與兩個鈣離子與香葉基單磷酸 (geranyl phosphate, C10-P) 穩定結合。然而，由於牽涉到兩個鈣離子結合的過程及構象轉變，以一般的熱力學研究方法，很難精確地描述整個過程。 在本實驗室之前的研究中，將LspC的相似物S1的兩個天門冬酸 (Aspartic acid, Asp) 改為絲胺酸 (Serine, Ser) ，成為能與苯硼酸(Phenylboronic acid, PBA) 結合之化合物 B1，並且在這篇研究中也利用生物實驗，證明了B1對於鈣離子的依賴性相較於S1大幅降低。 本次研究中，我們以B1能利用苯硼酸取代一個鈣離子的特性，將Laspartomycin C與兩個鈣離子結合的過程，簡化為一個苯硼酸及一個鈣離子的結合過程。我們也發現B1、PBA及C10-P需要同時存在，結合反應才能夠進行，是一件相當有趣的現象。在後續的實驗中也能以此為方向，對LspC的詳細結合過程做更深入的探討。

Laspartomycin C (LspC) is one of the most extensively studied calcium-dependent antibiotics (CDAs). Previous crystallographic studies have demonstrated that LspC can stably bind with two calcium ions and geranyl phosphate (C10-P). However, due to the involvement of two calcium ions and conformational changes, it is difficult to precisely describe the entire process using conventional thermodynamic methods. In our lab's previous research, the two aspartic acids (Asp) in the LspC analogue S1 were replaced with serine (Ser), creating compound B1, which can bind to phenylboronic acid (PBA). Biological experiments have shown that B1's dependency on calcium ions is significantly reduced compared to S1. In this study, we utilized B1's ability to replace one calcium ion with phenylboronic acid to simplify the process of LspC binding with two calcium ions into a process involving one phenylboronic acid and one calcium ion. We also discovered that B1, PBA, and C10-P must be present simultaneously for the binding reaction to occur, an interesting phenomenon. Future experiments can further explore the detailed binding process of LspC based on these findings.