ATP binding site in the plant ADP‐glucose pyrophosphorylase large subunit

Hwang, Seon‐Kap; Hamada, Shigeki; Okita, Thomas W.

doi:10.1016/j.febslet.2006.11.029

Cited by 29 publications

(38 citation statements)

References 20 publications

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“…The large subunit, then, can accumulate more nondeleterious nonsynonymous mutations for AGPase activity than can the small subunit. However, the roles of each AGPase subunit in enzyme function are not clear, since each subunit has activity when expressed alone in E. coli (Iglesias et al, 1993;Burger et al, 2003), and mutations in either subunit affect both catalytic and allosteric properties (Hannah and Nelson, 1976;Cross et al, 2004Cross et al, , 2005Hwang et al, 2006Hwang et al, , 2007. It should also be noted that the regulatory subunits of the Archaeal type H þ -ATPase and vacuolar type H þ -ATPase evolved at a slower rate compared with the catalytic subunits (Marin et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The Two AGPase Subunits Evolve at Different Rates in Angiosperms, yet They Are Equally Sensitive to Activity-Altering Amino Acid Changes When Expressed in Bacteria

et al. 2007

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The rate of protein evolution is generally thought to reflect, at least in part, the proportion of amino acids within the protein that are needed for proper function. In the case of ADP-glucose pyrophosphorylase (AGPase), this premise led to the hypothesis that, because the AGPase small subunit is more conserved compared with the large subunit, a higher proportion of the amino acids of the small subunit are required for enzyme activity compared with the large subunit. Evolutionary analysis indicates that the AGPase small subunit has been subject to more intense purifying selection than the large subunit in the angiosperms. However, random mutagenesis and expression of the maize (Zea mays) endosperm AGPase in bacteria show that the two AGPase subunits are equally predisposed to enzyme activity-altering amino acid changes when expressed in one environment with a single complementary subunit. As an alternative hypothesis, we suggest that the small subunit exhibits more evolutionary constraints in planta than does the large subunit because it is less tissue specific and thus must form functional enzyme complexes with different large subunits. Independent approaches provide data consistent with this alternative hypothesis.

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Section: Introductionmentioning

confidence: 99%

The Two AGPase Subunits Evolve at Different Rates in Angiosperms, yet They Are Equally Sensitive to Activity-Altering Amino Acid Changes When Expressed in Bacteria

et al. 2007

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“…Different approaches have been used in attempts to reveal the role of the two AGPase subunit types in higher plants. Numerous studies using various genetic, mutagenic, and biochemical strategies have strongly suggested that the SS has both catalytic and regulatory activities, and that the LS is mainly responsible for modulating the allosteric regulatory properties of the SS in the heterotetrameric enzyme (Ballicora et al 1995;Salamone et al 2000;Frueauf et al 2003;Hwang et al 2006). Although the LS is usually non-catalytic, recent studies have demonstrated that recombinant LSs (mutated or natural) show defective catalytic activity, both alone and in the presence of the SS in vitro Ventriglia et al 2008;Hwang et al 2008;Petreikov et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of cDNAs and genomic DNAs encoding ADP-glucose pyrophosphorylase large and small subunits from sweet potato

et al. 2015

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Interactions between different SSs and LSs were confirmed by a yeast two-hybrid experiment. Our findings provide comprehensive information about AGPase gene sequences, structures, expression profiles, and subunit interactions in sweet potato. The results can serve as a foundation for elucidation of molecular mechanisms of starch synthesis in tuberous roots, and should contribute to future regulation of starch biosynthesis to improve sweet potato starch yield.

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“…Even when the L subunit is not catalytic, it binds substrate and activator molecules. This may contribute to the synergistic effect seen when the L subunit influences the properties of the S subunit and vice versa (7)(8)(9).…”

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Ostreococcus tauri ADP-glucose Pyrophosphorylase Reveals Alternative Paths for the Evolution of Subunit Roles

Kuhn¹,

Falaschetti²,

Ballícora

2009

Journal of Biological Chemistry

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ADP-glucose pyrophosphorylase controls starch synthesis in plants and is an interesting case to study the evolution and differentiation of roles in heteromeric enzymes. It includes two homologous subunits, small (S) and large (L), that originated from a common photosynthetic eukaryotic ancestor. In present day organisms, these subunits became complementary after loss of certain roles in a process described as subfunctionalization. For instance, the potato tuber enzyme has a noncatalytic L subunit that complements an S subunit with suboptimal allosteric properties. To understand the evolution of catalysis and regulation in this family, we artificially synthesized both subunit genes from the unicellular alga Ostreococcus tauri. This is among the most ancient species in the green lineage that diverged from the ancestor of all green plants and algae. After heterologous gene expression, we purified and characterized the proteins. The O. tauri enzyme was not redox-regulated, suggesting that redox regulation of ADP-glucose pyrophosphorylases appeared later in evolution. The S subunit had a typical low apparent affinity for the activator 3-phosphoglycerate, but it was atypically defective in the catalytic efficiency (V max /K m ) for the substrate Glc-1-P. The L subunit needed the S subunit for soluble expression. In the presence of a mutated S subunit (to avoid interference), the L subunit had a high apparent affinity for 3-phosphoglycerate and substrates suggesting a leading role in catalysis. Therefore, the subfunctionalization of the O. tauri enzyme was different from previously described cases. To the best of our knowledge, this is the first biochemical description of a system with alternative subfunctionalization paths.Starch synthesis in photosynthetic eukaryotes such as higher plants and unicellular algae is controlled by a heterotetrameric ADP-glucose pyrophosphorylase (ADP-Glc PPase, 4 EC 2.7.7.27). This enzyme catalyzes the reaction of ATP and Glc-1-P to form ADP-glucose (ADP-Glc) and PP i , and it is primarily activated by 3-phosphoglycerate (3-PGA) and inhibited by P i . In photosynthetic eukaryotes the enzyme includes two distinct S and L homologous subunits (S 2 L 2 or ␣ 2 ␤ 2 ), but in photosynthetic bacteria the enzyme is a homotetramer (␣ 4 ). There has been debate regarding the role of the different subunits of ADP-Glc PPase. The S subunit homotetramer from potato (Solanum tuberosum) tuber (StuS), Arabidopsis thaliana (APS1), and barley (Hordeum vulgare) endosperm have a catalytic function with defective regulatory properties (1-3). It is not clear if there is a set of universal roles for the L subunit in plants. The L subunit from potato tuber (StuL) is catalytically deficient and plays more of a regulatory role by modifying the apparent affinity of the S subunit toward allosteric regulators (1, 4). On the other hand, the Arabidopsis APL1 and APL2 isoforms have both catalytic and regulatory functions, whereas the APL3 and APL4 isoforms behave like StuL (2, 5). The maize (Zea mays) endosperm L subunit...

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ATP binding site in the plant ADP‐glucose pyrophosphorylase large subunit

Cited by 29 publications

References 20 publications

The Two AGPase Subunits Evolve at Different Rates in Angiosperms, yet They Are Equally Sensitive to Activity-Altering Amino Acid Changes When Expressed in Bacteria

The Two AGPase Subunits Evolve at Different Rates in Angiosperms, yet They Are Equally Sensitive to Activity-Altering Amino Acid Changes When Expressed in Bacteria

Isolation and characterization of cDNAs and genomic DNAs encoding ADP-glucose pyrophosphorylase large and small subunits from sweet potato

Ostreococcus tauri ADP-glucose Pyrophosphorylase Reveals Alternative Paths for the Evolution of Subunit Roles

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