Construction of a Rhodobacter sphaeroides Strain That Efficiently Produces Hydrogen Gas from Acetate without Poly(β-Hydroxybutyrate) Accumulation: Insight into the Role of PhaR in Acetate Metabolism
Construction of a Rhodobacter sphaeroides Strain That Efficiently Produces Hydrogen Gas from Acetate without Poly(β-Hydroxybutyrate) Accumulation: Insight into the Role of PhaR in Acetate Metabolism
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构建可有效从乙酸产生氢气且不积累聚（β-羟基丁酸酯）的球形红杆菌菌株：深入了解 PhaR 在乙酸代谢中的作用
DOI：
10.1128/aem.00507-22
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发表时间：
2022
影响因子：
4.4
通讯作者：
Inui Masayuki
中科院分区：
文献类型：
--
作者：
Shimizu Tetsu;Teramoto Haruhiko;Inui Masayuki
紫色的非硫光养细菌球形红杆菌从醋酸盐中产生氢气。一种提高H_2产量的方法是防止一种被称为聚(β-羟基丁酸酯)的细胞内储能分子的积累，这种分子与H_2生产竞争降低功率。然而，根据遗传背景和/或培养条件的不同，PHB生物合成的中断已被报道会严重损害醋酸盐的同化。为了解决这一问题，我们分析了球形乳杆菌PHB积累与醋酸盐代谢的关系。基于野生型菌株的基因缺失分析表明，在基因组中的两个多羟基烷酸合成酶基因中，phaC1是PHB积累所必需的，而phaC2是PHB积累所必需的，并且phaC1缺失突变体在乙酸盐作用下生长缓慢。另一方面，缺失了phaC1和phaR的菌株在没有PHB积累的情况下表现出与野生型菌株相当的生长速度。这些结果表明，PHB的积累是醋酸盐通过改变phaR控制下的基因表达来实现正常生长所必需的。这一假说得到了转录组测序(RNA-seq)分析的支持，该分析表明phaR参与了乙基丙二酰辅酶A乙酸酯同化途径的调节。与这些发现一致的是，在基因工程产氢菌株中，由于生长缺陷，αC1的缺失导致醋酸盐产生的H_2减少，而同时缺失的αC_1恢复了醋酸盐的生长，并在没有PHB积累的情况下增加了醋酸盐的H_2产量。这项研究进一步表明，聚羟基烷酸不仅是细菌中碳和能量的储存物质，还可能作为信号分子介导细菌对特定环境的新陈代谢适应。这一概念将有助于理解产生聚羟基烷酸的细菌的生理学，以及通过合成生物学进行代谢工程。
The purple nonsulfur phototrophic bacterium Rhodobacter sphaeroides produces hydrogen gas (H2) from acetate. An approach to improve the H2production is preventing accumulation of an intracellular energy storage molecule known as poly(β-hydroxybutyrate) (PHB), which competes with H2production for reducing power. However, disruption of PHB biosynthesis has been reported to severely impair the acetate assimilation depending on the genetic backgrounds and/or culture conditions. To solve this problem, we analyzed the relationship between PHB accumulation and acetate metabolism in R. sphaeroides. Gene deletion analyses based on the wild-type strain revealed that among the two polyhydroxyalkanoate synthase genes in the genome,phaC1, but notphaC2, is essential for PHB accumulation, and thephaC1deletion mutant exhibited slow growth with acetate. On the other hand, a strain with the deletion ofphaC1together withphaR, which encodes a transcriptional regulator capable of sensing PHB accumulation, exhibited growth comparable to that of the wild-type strain despite no accumulation of PHB. These results suggest that PHB accumulation is required for normal growth with acetate by altering the expression of genes under the control ofphaR. This hypothesis was supported by a transcriptome sequencing (RNA-seq) analysis revealing thatphaRis involved in the regulation of the ethylmalonyl coenzyme A pathway for acetate assimilation. Consistent with these findings, deletion ofphaC1in a genetically engineered H2-producing strain resulted in lower H2production from acetate due to growth defects, whereas deletion ofphaRtogether withphaC1restored growth with acetate and increased H2production from acetate without PHB accumulation.IMPORTANCEThis study provides a novel approach for increasing the yield of photofermentative H2production from acetate by purple nonsulfur phototrophic bacteria. This study further suggests that polyhydroxyalkanoate is not only a storage substance for carbon and energy in bacteria, but may also act as a signaling molecule that mediates bacterial metabolic adaptations to specific environments. This notion will be helpful for understanding the physiology of polyhydroxyalkanoate-producing bacteria, as well as for their metabolic engineering via synthetic biology.
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影响因子：
2.1
作者：
A. Maehara;Y. Doi;T. Nishiyama;Yasuo Takagi;S. Ueda;Hideo Nakano;Tsuneo Yamane
通讯作者：
A. Maehara;Y. Doi;T. Nishiyama;Yasuo Takagi;S. Ueda;Hideo Nakano;Tsuneo Yamane
球形红细菌中 hemA 表达的控制 2.4.1：hbdA 基因中转座子插入的影响
影响因子：
3.2
作者：
Linda Fales;L. Kryszak;J. Zeilstra
通讯作者：
J. Zeilstra
影响因子：
4.1
作者：
SENIOR, PJ;BEECH, GA;DAWES, EA
通讯作者：
DAWES, EA
影响因子：
3.2
作者：
Maehara, A;Taguchi, S;Doi, Y
通讯作者：
Doi, Y
影响因子：
3.2
作者：
LAW, JH;SLEPECKY, RA
通讯作者：
SLEPECKY, RA