Abstract
Fragrance in rice plays an important characteristic feature in determining the quality of rice. 2-Acetyl-1-pyrroline (2AP) compound is responsible for the fragrance in rice. Betaine-aldehyde-dehydrogenase2 (BADH2) inhibits the biosynthesis of 2AP in nonfragrant rice by converting -aminobutyraldehyde (GAB-ald) to -aminobutyric acid (GABA). In fragrant rice, truncated BADH2 results in the accumulation of GAB-ald which then leads to the formation of 2AP. Biochemical and enzymatic studies state that the mutants of BADH2 exhibit lower enzymatic activity toward GAB-ald. In this study, we adopted an in-silico approach to explore the interaction behavior of model structures of native and mutant BADH2 enzyme and a substrate GAB-ald, which is responsible for fragrance in rice. Quantitative structural evaluations and salt bridge analysis were performed to identify the stability of BADH2 enzyme upon mutation. Our investigation states that the mutant forms of BADH2 have subsidiary/decisive catalytic efficiency toward GAB-ald, which was also endorsed with earlier in vivo experimental studies. Due to this, mutant forms of BADH2 were not able to interact with its substrate molecule GAB-ald; thus this phenomenon accumulates GAB-ald, and it leads to the formation of 2AP, which is responsible for the fragrance in the mutant variety. Based on the quantitative and docking analyses, we found that the BADH2 (N162A) was considered to be the most fragrant form. We list here the order of fragrance in rice as BADH2 <BADH2(C294A) <BADH2(E260A) <BADH2(N162A).