Expression of different GC content 16S rRNA genes in Haloarcula at different temperatures

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K19346
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Molecular and Genome biology and related fields
• Research Institution: Shizuoka University
• Principal Investigator: Kimura Hiroyuki 静岡大学, グリーン科学技術研究所, 教授 (30377717)
• Project Period (FY): 2017-06-30 – 2021-03-31
• Keywords: 温度適応 / 生育温度 / 好塩性アーキア / リボソームRNA / GC含量 / トランスクリプトーム解析

Outline of Final Research Achievements

Halophilic archaea harbour three copies of 16S rRNA genes (rrsA and rrsBC) in their genomes. While rrsB and rrsC show almost identical sequences, rrsA shows 1-3% guanine-plus-cytosine content (PGC) difference compared to rrsBC. Based on the strong correlation between the PGC of 16S rRNA genes and the growth temperatures of the prokaryotes, we hypothesiszed that high-PGC rrsA and low-PGC rrsBC are expressed at high and low temperatures, respectively. The secondary structure prediction of the 16 rRNA via computer simulation showed that the structural stability of 16S rRNAs transcribed from rrsA was higher than that of 16S rRNAs transcribed from rrsBC. We measured expression levels of rrsA and rrsBC under various temperature conditions by reverse-transcriptase quantitative PCR. The expression ratio of high-PGC rrsA to low-PGC rrsBC increased with cultivation temperatures. Our results suggest that 16S rRNAs transcribed from high-PGC rrsA function under high temperature conditions.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

本研究において、培養温度によって好塩性アーキアがGC含量の異なる16S rRNAを含むリボソームを使い分けるという新たな温度適応メカニズムに関する知見を得た。今後、高GC含量の16S rRNA遺伝子を含む新たなリボソームRNAオペロンやその転写制御遺伝子群をゲノムに組み込むことによって、原核生物の生育温度を5℃プラスする新たなバイオ手法に繋がる可能性がある。製薬、醸造、食品、水処理、環境浄化といった様々な産業分野で利活用されている有用微生物菌株の生育温度を5℃程度上昇させることができれば、バイオリアクターの冷却コストを大幅に削減することが可能となり、温暖化防止に貢献することができる。