Isolation of a heat-stable maize endosperm ADP-glucose pyrophosphorylase variant

作者：Georgelis Nikolaos; Hannah L Curtis^*

来源：Plant Science, 2008, 175(3): 247-254.

DOI：10.1016/j.plantsci.2008.04.005

• ADP-glucose
• heat stress
• starch
• random mutagenesis
• maize

Heat stress reduces maize yield and several lines of evidence suggest that the heat lability of maize endosperm ADP-glucose pyrophosphorylase (AGPase) contributes to this yield loss. AGPase catalyzes a rate-limiting step in starch synthesis. Herein, we present a novel maize endosperm AGPase small subunit variant, termed BT2-TI that harbors a single amino acid change of residue 462 from threonine to isoleucine. The mutant was isolated by random mutagenesis and heterologous expression in a bacterial system. BT2-TI exhibits enhanced heat stability compared to wildtype maize endosperm AGPase. The TI mutation was placed into another heat-stable small subunit variant, MP. MP is composed of sequences from the maize endosperm and the potato tuber small subunit. The MP-TI small subunit variant exhibited greater heat stability than did MP. Characterization of heat stability as well as kinetic and allosteric properties suggests that MP-TI may lead to increased starch yield when expressed in monocot endosperms.

• 出版日期2008-9