Backup Expression of the PhaP2 Phasin Compensates for phaP1 Deletion in Herbaspirillum seropedicae, Maintaining Fitness and PHB Accumulation.
Backup Expression of the PhaP2 Phasin Compensates for phaP1 Deletion in Herbaspirillum seropedicae, Maintaining Fitness and PHB Accumulation.
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DOI：
10.3389/fmicb.2016.00739
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发表时间：
2016
影响因子：
5.2
通讯作者：
Müller-Santos M
中科院分区：
文献类型：
--
作者：
Alves LP;Teixeira CS;Tirapelle EF;Donatti L;Tadra-Sfeir MZ;Steffens MB;de Souza EM;de Oliveira Pedrosa F;Chubatsu LS;Müller-Santos M
相位蛋白是控制聚-3-羟基丁酸酯（poly-3-hydroxybutyrate，PHB）颗粒形成、进入细胞的数量和稳定性的重要蛋白质。内生固氮菌Herbaspirillum seropedicae SmR 1的基因组测序揭示了两个同源相蛋白基因。为了验证亲株H.通过基因缺失获得phaP 1、phaP 2或这两个基因表达缺陷的同基因菌株，并在这项工作中进行表征。尽管PhaP 1和PhaP 2之间的序列高度相似，但PhaP 1是H. seropedicae，因为与亲本和Δ phaP 2相比，其缺失使PHB积累减少了约50%。在缺失phaP 1后，phaP 2的表达在Δ phaP 1菌株中增强了6倍。phaP 2的响应性备份表达部分挽救了Δ phaP 1突变体，维持了约50%的亲本PHB水平。双突变体ΔphaP1.2在任何生长阶段都不积累PHB，并且当葡萄糖为碳源时显示出严重的生长降低，这清楚地表明了适应性的负面影响。phaP 1和phaP 2同源基因在H.包括其他内生菌在内的血清型细菌的研究表明，phaP 2表达的相蛋白补偿机制可能在其他生物体中起作用，表明PHB代谢是内生细菌适应和效率的关键因素。
Phasins are important proteins controlling poly-3-hydroxybutyrate (PHB) granules formation, their number into the cell and stability. The genome sequencing of the endophytic and diazotrophic bacterium Herbaspirillum seropedicae SmR1 revealed two homologous phasin genes. To verify the role of the phasins on PHB accumulation in the parental strain H. seropedicae SmR1, isogenic strains defective in the expression of phaP1, phaP2 or both genes were obtained by gene deletion and characterized in this work. Despite of the high sequence similarity between PhaP1 and PhaP2, PhaP1 is the major phasin in H. seropedicae, since its deletion reduced PHB accumulation by ≈50% in comparison to the parental and ΔphaP2. Upon deletion of phaP1, the expression of phaP2 was sixfold enhanced in the ΔphaP1 strain. The responsive backup expression of phaP2 partially rescued the ΔphaP1 mutant, maintaining about 50% of the parental PHB level. The double mutant ΔphaP1.2 did not accumulate PHB in any growth stage and showed a severe reduction of growth when glucose was the carbon source, a clear demonstration of negative impact in the fitness. The co-occurrence of phaP1 and phaP2 homologous in bacteria relatives of H. seropedicae, including other endophytes, indicates that the mechanism of phasin compensation by phaP2 expression may be operating in other organisms, showing that PHB metabolism is a key factor to adaptation and efficiency of endophytic bacteria.