ARS | Publication request: Sucrose Synthase: Expanding Protein Function

Submitted to: Plant Signaling and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 2006
Publication Date: January 1, 2007
Citation: Chalivendra, S.C., Huber, S.C., Sachs, M.M., Rhoads, D.M. 2007. Sucrose Synthase: Expanding Protein Function. Plant Signaling and Behavior. 2(1):28-29.

Interpretive Summary: Past research shows that the enzyme sucrose synthase functions in carbohydrate metabolism. The goal here was to gain a fuller understanding of how sucrose synthase functions during its role in the response to low oxygen conditions in maize during flooding. Sucrose synthase appears to have an important role other than its known role as an enzyme in carbohydrate metabolism. In addition to being soluble in the cytosol, sucrose synthase localizes to mitochondria and the nucleus and in these locations apparently plays a novel alternative role, perhaps in signaling during flooding stress. The understanding of sucrose synthase’s role in a plant’s response to low oxygen-stress conditions will allow for a greater understanding of how these conditions cause a plant to alter protein synthesis in response to flooding and may allow for effective methods to produce crop plants that are tolerant to flooding.

Technical Abstract: Sucrose synthase (SUS: EC 2.4.1.13), a key enzyme in plant sucrose catabolism, is uniquely able to mobilize sucrose into multiple pathways involved in metabolic, structural, and storage functions. Our research indicates that the biological function of SUS may extend beyond its catalytic activity. This inference is based on the following observations: a) tissue-specific, isoform-dependent and metabolically-regulated association of SUS with mitochondria and b) isoform-specific and anoxia-responsive interaction of SUS with the voltage-dependent anion channel (VDAC), the major outer mitochondrial membrane protein. More recent work shows that both VDAC and SUS are also localized to the nucleus in maize seedling tissues. Their intricate regulation under anoxia indicates that these two proteins may have a role in inter-compartmental signaling.