| dc.description.abstract | Sucrose‐phosphate synthase (SPS) is a key enzyme catalyzing the formation of sucrose‐6‐phosphate through the
transfer of uridine‐diphosphate glucose (UDP‐G) as a donor to fructose‐6‐phosphate (F6P) as an acceptor. Plant SPS consists
of three main domains: N‐terminal, glycosyltransferase, and C‐terminal domains. Among these, the N‐terminal domain is
involved in regulating the allosteric activator glucose‐6‐phosphate (G6P). This study was directed toward determining the
regulation and characterization of N‐terminal truncated SPS in transgenic tomato. In this study, the N‐terminal truncated
mutant of sugarcane SPS (ΔN‐SoSPS1) and full‐length sugarcane SPS (FL‐SoSPS1) were expressed into tomato plants to
verify the functional role and importance of the N‐terminal domain in plant SPS. Overexpression of ΔN‐SoSPS1 led to an
up to 3‐fold increase in the specific activity of SPS compared to non‐transformant plants (WT), while the specific activity
of ΔN‐SoSPS1 was higher than FL‐SoSPS1 in transgenic tomato plants. Unlike WT and FL‐SoSPS1, the ΔN‐SoSPS1 mutant
was not allosterically regulated by G6P. These results indicated that deletion of the N‐terminal domain promotes the loss of
allosteric activation by G6P and increases binding affinity between enzyme and substrate. | en_US |
