Figure 6
(a) Electrostatic surface potential of OsMDHAR shows that the surface of the AsA binding site is highly basic. (b) Close-up view of the electron transfer pathway from NAD to AsA via FAD by flanking Tyr349. (c) Proposed electron transfer mechanism of OsMDHAR. Left, reduction process of the first FMN by the stacked NADH; middle, reduction process of the Tyr349 by the FMN; right, reduction process of the bound substrate (MDHA) by the Tyr349. The backbone amide nitrogen atom of Val316 is within hydrogen bonding distance (3.15 Å), which can either stabilize the negative charge of the semiquinone from or provide a proton to it. The arrows indicate the movement of an electron. (d) Comparison of adaptation ability to oxidative stress in OsDHAR- and OsMDHAR-expressing yeast cells. Mid-log phase yeast cells were exposed to 20 mM H2O2 for 1 h, serially diluted with YPD medium, and spotted onto a YPD agar plate. 1, wild-type (WT) cells with an empty vector alone; 2, WT cells expressing OsMDHAR; 3, WT cells expressing OsDHAR.
