Lipid A and O-chain modifications cause Rhizobium lipopolysaccharides to become hydrophobic during bacteroid development
Lipid A and O-chain modifications cause Rhizobium lipopolysaccharides to become hydrophobic during bacteroid development
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DOI：
10.1046/j.1365-2958.2001.02225.x
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发表时间：
2001-01-01
影响因子：
3.6
通讯作者：
Carlson, RW
中科院分区：
文献类型：
--
作者：
Kannenberg, EL;Carlson, RW
研究了豌豆根瘤菌3841在3种不同生长条件下对脂多糖结构的影响。用热酚-水从培养的细胞中提取的LPS被分离成亲水性水相和/或疏水性酚相。大部分的LPS从标准条件下生长的细胞提取到水相，但更大比例的LPS提取到苯酚相从细胞生长在酸性或还原氧条件下，或当从根瘤中分离的类细菌。与水提取的LPS相比，苯酚提取的LPS含有更大程度的糖基甲基化和O-乙酰化，木糖，葡萄糖和甘露糖的水平增加，并增加连接到脂质A部分的长链脂肪酸的量。水相和酚相的LPS也不同，它们与单克隆抗体的反应性和它们的聚丙烯酰胺凝胶电泳带型。在还原氧条件下生长的根瘤菌的酚提取的LPS在其化学性质、与单克隆抗体的反应性和提取行为方面与从豌豆根瘤菌（即主要是类菌体）分离的大部分LPS非常相似。这一发现表明，在共生类杆菌的发展，降低氧张力诱导结构的修改，导致主要从亲水性的开关，主要是疏水性的分子形式的LPS。增加的LPS的疏水性也正相关的增加，在整个细胞的表面疏水性，如所示的高度粘附的碳氢化合物的细菌细胞分离的结节或从培养物生长在低氧条件下。这些LPS修改的影响进行了讨论根瘤菌的生存和功能在不同的土壤和植物栖息地。
Modifications to the lipopolysaccharide (LPS) structure caused by three different growth conditions were investigated in the pea-nodulating strain Rhizobium leguminosarum 3841. The LPSs extracted by hot phenol-water from cultured cells fractionated into hydrophilic water and/or hydrophobic phenol phases. Most of the LPSs from cells grown under standard conditions extracted into the water phase, but a greater proportion of LPSs were extracted into the phenol phase from cells grown under acidic or reduced-oxygen conditions, or when isolated from root nodules as bacteroids. Compared with the water-extracted LPSs, the phenol-extracted LPSs contained greater degrees of glycosyl methylation and O-acetylation, increased levels of xylose, glucose and mannose and increased amounts of long-chain fatty acids attached to the lipid A moiety. The water- and phenol-phase LPSs also differed in their reactivity with monoclonal antibodies and in their polyacrylamide gel electrophoretic banding patterns. Phenol-extracted LPSs from rhizobia grown under reduced-oxygen conditions closely resembled the bulk of LPSs isolated from pea nodule bacteria (i.e. mainly bacteroids) in their chemical properties, reactivities with monoclonal antibodies and extraction behaviour. This finding suggests that, during symbiotic bacteroid development, reduced oxygen tension induces structural modifications in LPSs that cause a switch from predominantly hydrophilic to predominantly hydrophobic molecular forms. Increased hydrophobicity of LPSs was also positively correlated with an increase in the surface hydrophobicity of whole cells, as shown by the high degree of adhesion to hydrocarbons of bacterial cells isolated from nodules or from cultures grown under low-oxygen conditions. The implications of these LPS modifications are discussed for rhizobial survival and function in different soil and in planta habitats.