Elucidation of a novel lipid A α-(1,1)-GalA transferase gene (rgtF) from Mesorhizobium loti: Heterologous expression of rgtF causes Rhizobium etli to synthesize lipid A with α-(1,1)-GalA
Elucidation of a novel lipid A α-(1,1)-GalA transferase gene (rgtF) from Mesorhizobium loti: Heterologous expression of rgtF causes Rhizobium etli to synthesize lipid A with α-(1,1)-GalA
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DOI：
10.1093/glycob/cws223
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发表时间：
2013-05-01
期刊：
影响因子：
4.3
通讯作者：
Carlson, Russell W.
中科院分区：
文献类型：
--
作者：
Brown, Dusty B.;Muszynski, Artur;Carlson, Russell W.
报道了一种不寻常的α-（1，1）-半乳糖醛酸（GalA）脂质A修饰存在于许多革兰氏阴性菌的脂多糖中，包括固氮菌Azoacetyllum lipoferum，Mesorhizobium huakuii和M. loti、茎形成细菌新月柄杆菌（Caulobacter crescentus）和超嗜热细菌风产液菌（Aquifex aeolicus）。然而，α-（1，1）-GalA转移酶（GalAT）基因，我们将其命名为RgtF，未被鉴定。根瘤菌属的物种用α-（1，4 '）-GalA而不是α-（1，1）-GalA产生脂质A。根瘤菌GalAT，RgtD，是脂质A α-（1- 4 '）-GalAT，其利用脂质供体十二异戊二烯基-磷酸GalA（Dod-P-GalA）进行GalA转移。另外的根瘤菌GalAT，RgtE，是生物合成Dod-P-GalA所必需的。我们预测候选rgtF基因在已知产生脂质A与α-（1，1）-GalA的细菌物种。为了确定预测的rgtF基因功能，我们克隆了M. loti rgtF基因导入表达质粒，并将该质粒导入不含rgtF基因也不产生脂质A α-（1，1）-GalA的etli根瘤菌菌株。基质辅助激光解吸/电离飞行时间质谱分析结合NMR研究表明，从这些rgtF-补充菌株的脂质As被修改与附加的α-（1，1）-GalA连接到近端的葡萄糖胺。
An unusual alpha-(1,1)-galacturonic acid (GalA) lipid A modification has been reported in the lipopolysaccharide of a number of interesting Gram-negative bacteria, including the nitrogen-fixing bacteria Azospirillum lipoferum, Mesorhizobium huakuii and M. loti, the stalk-forming bacterium Caulobacter crescentus and the hyperthermophilic bacterium Aquifex aeolicus. However, the alpha-(1,1)-GalA transferase (GalAT) gene, which we have named RgtF, was not identified. Species of the Rhizobium genera produce lipid A with alpha-(1,4')-GalA but not alpha-(1,1)-GalA. The Rhizobium GalAT, RgtD, is the lipid A alpha-(1-4')-GalAT which utilizes the lipid donor dodecaprenyl-phosphate GalA (Dod-P-GalA) for GalA transfer. An additional Rhizobium GalAT, RgtE, is required for the biosynthesis of Dod-P-GalA. We predicted candidate rgtF genes in bacterial species known to produce lipid A with alpha-(1,1)-GalA. In order to determine the predicted rgtF gene function, we cloned the M. loti rgtF gene into an expression plasmid and introduced that plasmid into Rhizobium etli strains that do not contain the rgtF gene nor produce lipid A alpha-(1,1)-GalA. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis combined with NMR studies revealed that the lipid As from these rgtF-complemented strains were modified with an additional alpha-(1,1)-GalA attached to the proximal glucosamine.