Major Isoforms of Starch Branching Enzymes in Premature Seeds of Kidney Bean (Phaseolus vulgaris L.)

Nozaki, Kouichi; Hamada, Shigeki; Nakamori, Tomoko; Ito, Hiroyuki; Sagisaka, Shonosuke; Yoshida, Hironori; Takeda, Yasuhito; Honma, Mamoru; Matsui, Hirokazu

doi:10.1271/bbb.65.1141

Cited by 24 publications

(26 citation statements)

References 23 publications

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“…Citrate can activate SS activity, by lowering the K m for the a-glucan primer, and can stimulate both spinach leaf (Spinacia oleracea L.) and bean (Phaseolus vulgaris) SBEs (6,26). The activity of a number of starch biosynthetic enzymes has been shown to be modified by redox state, and activities of Arabidopsis SBE 2.1 and 2.2 were enhanced under reducing conditions (10).…”

Section: Figmentioning

confidence: 99%

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

2014

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Starch-branching enzymes (SBEs) are one of the four major enzyme classes involved in starch biosynthesis in plants and algae, and their activities play a crucial role in determining the structure and physical properties of starch granules. SBEs generate a-1,6-branch linkages in a-glucans through cleavage of internal a-1,4 bonds and transfer of the released reducing ends to C-6 hydroxyls. Starch biosynthesis in plants and algae requires multiple isoforms of SBEs and is distinct from glycogen biosynthesis in both prokaryotes and eukaryotes which uses a single branching enzyme (BE) isoform. One of the unique characteristics of starch structure is the grouping of a-1,6-branch points in clusters within amylopectin. This is a feature of SBEs and their interplay with other starch biosynthetic enzymes, thus facilitating formation of the compact water-insoluble semicrystalline starch granule. In this respect, the activity of SBE isoforms is pivotal in starch granule assembly. SBEs are structurally related to the aamylase superfamily of enzymes, sharing three domains of secondary structure with prokaryotic Bes: the central (b/a) 8 -barrel catalytic domain, an NH 2 -terminal domain involved in determining the size of a-glucan chain transferred, and the C-terminal domain responsible for catalytic capacity and substrate preference. In addition, SBEs have conserved plant-specific domains, including phosphorylation sites which are thought to be involved in regulating starch metabolism. SBEs form heteromeric protein complexes with other SBE isoforms as well as other enzymes involved in starch synthesis, and assembly of these protein complexes is regulated by protein phosphorylation. Phosphorylated SBEIIb is found in multienzyme complexes with isoforms of glucan-elongating starch synthases, and these protein complexes are implicated in amylopectin cluster formation. This review presents a comparative overview of plant SBEs and includes a review of their properties, structural and functional characteristics, and recent developments on their posttranslational regulation.

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Section: Figmentioning

confidence: 99%

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

2014

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“…N-terminal primary sequences of several SBEs and identification of the large form of PvSBE2. A, alignment of mature N-terminal primary sequences of kidney bean PvSBE2 (16,17), pea SBEI (19), rice RBE3 (22), and maize BEIIb (21). Regions I and II represent two of the four regions conserved among ␣-amylase family enzymes.…”

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confidence: 99%

“…ture, thermal stability, citrate effects, and kinetic parameters were examined as described previously (16).…”

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confidence: 99%

“…To investigate the relationships between structure and function of SBEs, as well as its mode of action in starch biosynthe-sis, we isolated and characterized a SBE isozyme (PvSBE2) from immature seeds of the kidney bean (Phaseolus vulgaris L.) (16). A comparison of the determined N-terminal sequence of purified PvSBE2 to the primary sequence derived from pvsbe2 cDNA suggested that PvSBE2 was produced from a preprotein with a plastid signal leader sequence of 156 residues (16,17).…”

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“…A comparison of the determined N-terminal sequence of purified PvSBE2 to the primary sequence derived from pvsbe2 cDNA suggested that PvSBE2 was produced from a preprotein with a plastid signal leader sequence of 156 residues (16,17). Additionally, comparison of the primary sequence of PvSBE2 to other plant SBEs such as pea SBEI (18,19), maize BEIIb (20,21), and rice RBE3 (22) showed that despite sharing considerable sequence homology with these other SBEs, PvSBE2 is shorter by about 50 -100 amino acid residues (Fig.…”

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Differential Characteristics and Subcellular Localization of Two Starch-branching Enzyme Isoforms Encoded by a Single Gene inPhaseolus vulgaris L.

Hamada¹,

Ito²,

Hiraga³

et al. 2002

Journal of Biological Chemistry

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Starch-branching enzymes (SBE) have a dominant role for amylopectin structure as they define chain length and frequency of branch points. We have previously shown that one of the SBE isoforms of kidney bean (Phaseolus vulgaris L.), designated PvSBE2, has a molecular mass (82 kDa) significantly smaller than those reported for isologous SBEs from pea (SBEI), maize (BEIIb), and rice (RBE3). Additionally, in contrast to the dual location of the pea SBEI in both the soluble and starch granule fractions, PvSBE2 was found only in the soluble fraction during seed development. Analysis of a pvsbe2 cDNA suggested that PvSBE2 is generated from a larger precursor with a putative plastid targeting sequence of 156 residues. Here we describe the occurrence of a larger 100-kDa form (LF-PvSBE2) of PvSBE2 found both in the soluble and starch granule fractions of the developing seeds. The determined N-terminal sequence, VKSSHDSD, of LFPvSBE2 corresponded to a peptide sequence located 111 amino acids upstream from the N terminus of purified PvSBE2, suggesting that LF-PvSBE2 and PvSBE2 are products of the same gene. Analysis of the products by 5-RACE (rapid amplification of cDNA ends) and reverse transcription PCR indicated that the two transcripts for pre-LF-PvSBE2 and pre-PvSBE2 are generated by alternative splicing. Recombinant LF-PvSBE2 (rLF-PvSBE2) was purified from Escherichia coli and the kinetic properties were compared with those of recombinant PvSBE2 (rPvSBE2). rLF-PvSBE2 had much higher affinity for amylopectin (K m ‫؍‬ 4.4 mg/ml) than rPvSBE2 (18.4 mg/ml), whereas the V max of rLF-PvSBE2 (135 units/mg) for this substrate was much lower than that of rPvSBE2 (561 units/mg). These results suggest that the N-terminal extension of LF-PvSBE2 plays a critical role for localization in starch granules by altering its enzymatic properties.Starch, one of the most important carbon reserves in plants, is composed of two glucan polymers, amylose and amylopectin.

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1,4-α-Glucan branching enzyme

Springer Handbook of Enzymes

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Major Isoforms of Starch Branching Enzymes in Premature Seeds of Kidney Bean (Phaseolus vulgaris L.)

Cited by 24 publications

References 23 publications

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

Differential Characteristics and Subcellular Localization of Two Starch-branching Enzyme Isoforms Encoded by a Single Gene inPhaseolus vulgaris L.

1,4-α-Glucan branching enzyme

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