Siriya ThammachatNuanwan PungtanomSomruathai KidsanguanWanwarang PathaichindachoteBoonhiang PromdonkoyChartchai KrittanaiMahidol UniversityThailand National Center for Genetic Engineering and Biotechnology2018-09-242018-09-242010-01-01BMB Reports. Vol.43, No.6 (2010), 427-4311976670X197666962-s2.0-77955785259https://repository.li.mahidol.ac.th/handle/20.500.14594/28824Cyt2Aa2 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 β1 and C-terminal αF 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 β1 has a critical effect on dimer formation and structural stability against proteases. In addition, amino acids N230 and I233-F237 around the C-terminus αF demonstrated a crucial role in protecting the protoxin from proteolytic digestion. These results suggested that β1 and αF on the N- and C-terminal ends of Cyt2Aa2 protoxin play an important role in the molecular interaction and in maintaining the structural stability of the protoxin.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyArticleSCOPUS10.5483/BMBRep.2010.43.6.427