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- Title
One of the isoamylase isoforms, CMI294C, is required for semi-amylopectin synthesis in the rhodophyte Cyanidioschyzon merolae.
- Authors
Toshiki Maeno; Yuki Yamakawa; Yohei Takiyasu; Hiroki Miyauchi; Yasunori Nakamura; Masami Ono; Noriaki Ozaki; Yoshinori Utsumi; Ugo Cenci; Colleoni, Christophe; Ball, Steven; Mikio Tsuzuki; Shoko Fujiwara
- Abstract
Most rhodophytes synthesize semi-amylopectin as a storage polysaccharide, whereas some species in the most primitive class (Cyanidiophyceae) make glycogen. To know the roles of isoamylases in semi-amylopectin synthesis, we investigated the effects of isoamylase gene (CMI294C and CMS197C)- deficiencies on semi-amylopectin molecular structure and starch granule morphology in Cyanidioschyzon merolae (Cyanidiophyceae). Semiamylopectin content in a CMS197C-disruption mutant (CMS197C) was not significantly different from that in the control strain, while that in a CMI294Cdisruption mutant (CMI294C) was much lower than those in the control strain, suggesting that CMI294C is essential for semi-amylopectin synthesis. Scanning electron microscopy showed that the CMI294C strain contained smaller starch granules, while the CMS197C strain had normal size, but donut-shaped granules, unlike those of the control strain. Although the chain length distribution of starch from the control strain displayed a semiamylopectin pattern with a peak around degree of polymerization (DP) 11-13, differences in chain length profiles revealed that the CMS197C strain has more short chains (DP of 3 and 4) than the control strain, while the CMI294C strain has more long chains (DP =12). These findings suggest that CMI294Ctype isoamylase, which can debranch a wide range of chains, probably plays an important role in semi-amylopectin synthesis unique in the Rhodophyta.
- Subjects
AMYLOPECTIN; DEGREE of polymerization; POLYSACCHARIDES; SCANNING electron microscopy; MOLECULAR structure; STARCH
- Publication
Frontiers in Plant Science, 2022, Vol 13, p1
- ISSN
1664-462X
- Publication type
Article
- DOI
10.3389/fpls.2022.967165