Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand.
BMB Rep. 2010 Jun;43(6):427-31. doi: 10.5483/bmbrep.2010.43.6.427.
Cyt2Aa2 is a mosquito-larvicidal protein produced as a 29 kDa crystalline protoxin from Bacillus thuringiensis subsp. darmstadiensis. To become an active toxin, proteolytic processing is required to remove amino acids from its N- and C-termini. This study aims to investigate the functional role of amino acid residues on the N-terminal Beta1 and C-terminal alphaF of Cyt2Aa2 protoxin. Mutant protoxins were constructed, characterized and compared to the wild type Cyt2Aa2. Protein expression data and SDS-PAGE analysis revealed that substitution at leucine- 33 (L33) of Beta1 has a critical effect on dimer formation and structural stability against proteases. In addition, amino acids N230 and I233-F237 around the C-terminus alphaF demonstrated a crucial role in protecting the protoxin from proteolytic digestion. These results suggested that Beta1 and alphaF on the Nand C-terminal ends of Cyt2Aa2 protoxin play an important role in the molecular interaction and in maintaining the structural stability of the protoxin.
Cyt2Aa2 是一种由苏云金芽孢杆菌亚种 darmstadiensis 产生的 29kDa 晶体原毒素，具有杀蚊幼虫的特性。为了成为一种活性毒素，需要进行蛋白水解加工，从其 N 端和 C 端去除氨基酸。本研究旨在探讨 Cyt2Aa2 原毒素 N 端β1 和 C 端αF 上氨基酸残基的功能作用。构建了突变原毒素，并对其进行了表征和与野生型 Cyt2Aa2 的比较。蛋白表达数据和 SDS-PAGE 分析表明，β1 上的亮氨酸 33（L33）取代对二聚体形成和蛋白酶抗性的结构稳定性有重要影响。此外，C 端αF 周围的氨基酸 N230 和 I233-F237 在保护原毒素免受蛋白水解消化方面也起着至关重要的作用。这些结果表明，Cyt2Aa2 原毒素 N 端和 C 端的β1 和αF 对分子相互作用和原毒素的结构稳定性起着重要作用。
