The Very Long Chain Fatty Acid (C(26):25OH) Linked to the Lipid A Is Important for the Fitness of the Photosynthetic Bradyrhizobium Strain ORS278 and the Establishment of a Successful Symbiosis with Aeschynomene Legumes.
The Very Long Chain Fatty Acid (C(26):25OH) Linked to the Lipid A Is Important for the Fitness of the Photosynthetic Bradyrhizobium Strain ORS278 and the Establishment of a Successful Symbiosis with Aeschynomene Legumes.
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DOI：
10.3389/fmicb.2017.01821
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发表时间：
2017
影响因子：
5.2
通讯作者：
Giraud E
中科院分区：
文献类型：
--
作者：
Busset N;Di Lorenzo F;Palmigiano A;Sturiale L;Gressent F;Fardoux J;Gully D;Chaintreuil C;Molinaro A;Silipo A;Giraud E
在根瘤菌菌株中，脂质A通过添加极长链脂肪酸（VLCFA）来修饰，所述极长链脂肪酸（VLCFA）在外膜的硬化中发挥重要作用，从而促进其植物内外的双重生命周期。在慢生根瘤菌属菌株中，脂质A更复杂，存在至少两个VLCFA，一个共价连接到hopanoid分子，但这些修饰的重要性还没有得到很好的理解。在这项研究中，我们确定了一个簇VLCFA基因的光合慢生根瘤菌株ORS 278，结瘤的Aeschynomene植物在一个结瘤因子的独立过程。我们试图突变VLCFA基因簇的不同基因以阻止VLCFA的合成，但仅获得了编码酰基转移酶的lpxXL基因中的一个突变体。脂质A的结构分析表明，LpxXL参与C26：25 OH VLCFA向脂质A的转移，但不参与含有hopanoid分子的C30：29 OH VLCFA的转移。尽管保持第二VLCFA，突变体的能力，以科普各种压力（低pH值，高温，高渗透压，和抗菌肽），并建立一个有效的固氮共生急剧下降。与此同时，我们研究了BRADO 0045基因（编码与载脂蛋白N-酰基转移酶Lnt具有弱同一性的推定酰基转移酶）是否参与C30：29 OH VLCFA向脂质A的转移。虽然该突变体表现出与lpxXL突变体相似的表型，但没有观察到脂质A结构与野生型菌株中的脂质A结构的差异，表明该基因不参与脂质A的修饰。我们的研究结果推进了我们的知识的生物合成途径和VLCFAs修饰的脂质A的自由生活和共生状态的慢生根瘤菌菌株的作用。
In rhizobium strains, the lipid A is modified by the addition of a very long-chain fatty acid (VLCFA) shown to play an important role in rigidification of the outer membrane, thereby facilitating their dual life cycle, outside and inside the plant. In Bradyrhizobium strains, the lipid A is more complex with the presence of at least two VLCFAs, one covalently linked to a hopanoid molecule, but the importance of these modifications is not well-understood. In this study, we identified a cluster of VLCFA genes in the photosynthetic Bradyrhizobium strain ORS278, which nodulates Aeschynomene plants in a Nod factor-independent process. We tried to mutate the different genes of the VLCFA gene cluster to prevent the synthesis of the VLCFAs, but only one mutant in the lpxXL gene encoding an acyltransferase was obtained. Structural analysis of the lipid A showed that LpxXL is involved in the transfer of the C26:25OH VLCFA to the lipid A but not in the one of the C30:29OH VLCFA which harbors the hopanoid molecule. Despite maintaining the second VLCFA, the ability of the mutant to cope with various stresses (low pH, high temperature, high osmolarity, and antimicrobial peptides) and to establish an efficient nitrogen-fixing symbiosis was drastically reduced. In parallel, we investigated whether the BRADO0045 gene, which encodes a putative acyltransferase displaying a weak identity with the apo-lipoprotein N-acyltransferase Lnt, could be involved in the transfer of the C30:29OH VLCFA to the lipid A. Although the mutant exhibited phenotypes similar to the lpxXL mutant, no difference in the lipid A structure was observed from that in the wild-type strain, indicating that this gene is not involved in the modification of lipid A. Our results advance our knowledge of the biosynthesis pathway and the role of VLCFAs-modified lipid A in free-living and symbiotic states of Bradyrhizobium strains.
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影响因子：
3.5
作者：
Bonaldi, Katia;Gargani, Daniel;Giraud, Eric
通讯作者：
Giraud, Eric
影响因子：
3.2
作者：
Brown, Dusty B.;Huang, Yu-Chu;Carlson, Russell W.
通讯作者：
Carlson, Russell W.
影响因子：
3.2
作者：
Ardissone, Silvia;Kobayashi, Hajime;Deakin, William J.
通讯作者：
Deakin, William J.
影响因子：
3.6
作者：
Kannenberg, EL;Carlson, RW
通讯作者：
Carlson, RW
影响因子：
6.4
作者：
Kulkarni G;Busset N;Molinaro A;Gargani D;Chaintreuil C;Silipo A;Giraud E;Newman DK
通讯作者：
Newman DK