Fig. 6: Proposed working model for the regulation of OsASTOL1 in sulfur metabolism in rice.
From: A molecular switch in sulfur metabolism to reduce arsenic and enrich selenium in rice grain
Schematic overview of enzymatic reactions (black arrows) and metabolites involved in the sulfur metabolism and its regulatory mechanism. In wild type rice, OAS is produced by cysteine synthase complex (CSC), which results in two effects: (i) induces expression of genes in sulfate uptake and assimilation (blue arrow) to enhance the supply of sulfide; (ii) dissociates the cysteine synthase complex (solid red line) to inactivate SAT. These effects control the flux of S towards cysteine synthesis in vivo. However, in the astol1 mutant, the mutated OsASTOL1S189N protein is difficult to be dissociated from the CSC by OAS (dotted red line), which results in SAT being constitutively active and producing more OAS. Increased OAS level enhances sulfate/selenate uptake and assimilatory reduction and arsenic detoxification (bigger size of black and blue arrows).
