Hirokawa Yasutaka, Kanesaki Yu, Arai Sayuri, Saruta Fumiko, Hayashihara Kayoko, Murakami Akio, Shimizu Kazunori, Honda Hiroyuki, Yoshikawa Hirofumi, Hanai Taizo
Laboratory for Bioinformatics, Graduate School of Systems Life Sciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
NODAI Genome Research Center, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
J Biosci Bioeng. 2018 May;125(5):572-577. doi: 10.1016/j.jbiosc.2017.11.012.
The production of alcohols directly from carbon dioxide by engineered cyanobacteria is an attractive technology for a sustainable future. Enhanced tolerance to the produced alcohols would be a desirable feature of the engineered cyanobacterial strains with higher alcohol productivity. We have recently obtained the mutant strains of Synechococcus elongatus PCC 7942 with higher tolerance to isopropanol using a single-cell screening system (Arai et al., Biotechnol. Bioeng., 114, 1771-1778, 2017). Among the mutant strains, SY1043 showed the highest isopropanol tolerance. Interestingly, SY1043 also showed higher tolerance to other alcohols such as ethanol and 1-butanol, however, the mechanisms involved in enhancing this alcohol tolerance were unclear. To reveal the alcohol tolerance mechanism of SY1043, we investigated the relationship between alcohol tolerance and four mutations found in SY1043 by genome resequencing analysis. Isopropanol tolerance was enhanced by amino acid substitution (Leu285Pro) in a hypothetical protein encoded by Synpcc7942_0180 of the wild type strain TA1297. TA4135, into which this mutation was introduced, showed a same tendency of tolerance to other alcohols (ethanol and 1-butanol).
通过工程改造的蓝细菌直接将二氧化碳转化为醇类，对于可持续发展的未来而言是一项颇具吸引力的技术。提高对所产生醇类的耐受性，将是具有更高醇类生产率的工程蓝细菌菌株所期望具备的特性。我们最近利用单细胞筛选系统获得了对异丙醇具有更高耐受性的聚球藻属细长聚球藻PCC 7942突变菌株（Arai等人，《生物技术与生物工程》，第114卷，第1771 - 1778页，2017年）。在这些突变菌株中，SY1043表现出最高的异丙醇耐受性。有趣的是，SY1043对其他醇类如乙醇和1 - 丁醇也表现出更高的耐受性，然而，增强这种醇类耐受性所涉及的机制尚不清楚。为了揭示SY1043的醇类耐受性机制，我们通过基因组重测序分析研究了醇类耐受性与在SY1043中发现的四个突变之间的关系。野生型菌株TA1297的Synpcc7942_0180编码的一种假定蛋白质中的氨基酸替换（Leu285Pro）增强了异丙醇耐受性。引入了该突变的TA4135对其他醇类（乙醇和1 - 丁醇）也表现出相同的耐受趋势。
