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Biochem Biophys Res Commun. 2017 Mar 18;484(4):839-844. doi: 10.1016/j.bbrc.2017.01.185. Epub 2017 Feb 2.

Base-pair opening dynamics of the microRNA precursor pri-miR156a affect temperature-responsive flowering in Arabidopsis.

Author information

1
Department of Chemistry and RINS, Gyeongsang National University, Gyeongnam 52828, South Korea.
2
Creative Research Initiatives, Department of Life Sciences, Korea University, Seoul 02841, South Korea.
3
Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 02792, South Korea.
4
Department of Chemistry and RINS, Gyeongsang National University, Gyeongnam 52828, South Korea. Electronic address: joonhwa@gnu.ac.kr.
5
Creative Research Initiatives, Department of Life Sciences, Korea University, Seoul 02841, South Korea. Electronic address: jahn@korea.ac.kr.

Abstract

Internal and environmental cues, including ambient temperature changes, regulate the timing of flowering in plants. Arabidopsis miR156 represses flowering and plays an important role in the regulation of temperature-responsive flowering. However, the molecular basis of miR156 processing at lower temperatures remains largely unknown. Here, we performed nuclear magnetic resonance studies to investigate the base-pair opening dynamics of model RNAs at 16 °C and investigated the in vivo effects of the mutant RNAs on temperature-responsive flowering. The A9C and A10CG mutations in the B5 bulge of the lower stem of pri-miR156a stabilized the C15∙G98 and U16∙A97 base-pairs at the cleavage site of pri-miR156a at 16 °C. Consistent with this, production of mature miR156 was severely affected in plants overexpressing the A9C and A10CG constructs and these plants exhibited almost no delay in flowering at 16 °C. The A10G and A9AC mutations did not strongly affect C15∙G98 and U16∙A97 base-pairs at 16 °C, and plants overexpressing A10G and A9AC mutants of miR156 produced more mature miR156 than plants overexpressing the A9C and A10CG mutants and showed a strong delay in flowering at 16 °C. Interestingly, the A9AC mutation had distinct effects on the opening dynamics of the C15∙G98 and U16∙A97 base-pairs between 16 °C and 23 °C, and plants expressing the A9AC mutant miR156 showed only a moderate delay in flowering at 16 °C. Based on these results, we propose that fine-tuning of the base-pair stability at the cleavage site is essential for efficient processing of pri-miR156a at a low temperature and for reduced flowering sensitivity to ambient temperature changes.

KEYWORDS:

Base-pair opening dynamics; Flowering; Microrna biogenesis; NMR; RNA

PMID:
28161630
DOI:
10.1016/j.bbrc.2017.01.185
[Indexed for MEDLINE]

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