Ralstonia solanacearum RSp0194 Encodes a Novel 3-Keto-Acyl Carrier Protein Synthase III.
Ralstonia solanacearum RSp0194 Encodes a Novel 3-Keto-Acyl Carrier Protein Synthase III.
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DOI：
10.1371/journal.pone.0136261
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Wang HH
中科院分区：
文献类型：
--
作者：
Mao YH;Ma JC;Li F;Hu Z;Wang HH
脂肪酸合成（FAS）是一种主要代谢途径，对于细菌的生存至关重要。青枯雷尔氏菌（Ralstonia solanacearum）是β-变形菌门的一个成员，其引起的细菌性枯萎病影响200多种植物物种，包括许多经济上重要的植物。然而，迄今为止，R.青枯菌尚未得到充分研究。在这项研究中，我们确定了两种形式的3-酮-ACP合成酶III，RsFabH和RsFabW，在R。青枯菌属RsFabH是大肠杆菌FabH的同源物，由染色体RSc 1050基因编码，在体外脂肪酸生物合成的起始步骤中催化乙酰辅酶A与丙二酰ACP的缩合。RsfabH突变体失去了从头合成脂肪酸的能力，并在含有游离脂肪酸的培养基中生长。RsFabW是铜绿假单胞菌PA 3286的同源物，由大质粒基因RSp 0194编码，在体外将酰基-CoA（C2-CoA至C10-CoA）与丙二酰-ACP缩合以产生3-酮基-酰基-ACP。虽然RsfabW突变体是可行的，RsfabW是负责RsfabH突变体生长在培养基中含有游离脂肪酸。RsFabW在体外可与丙二酰-ACP缩合生成3-酮基-酰基-ACP，表明RsFabW在红曲霉脂肪酸合成中具有特殊的作用。青枯菌属所有这些数据都证实了R.青枯菌不仅利用乙酰-CoA，而且利用中链酰基-CoA或酰基-ACP作为引发脂肪酸合成的引物。
Fatty acid synthesis (FAS), a primary metabolic pathway, is essential for survival of bacteria. Ralstonia solanacearum, a β-proteobacteria member, causes a bacterial wilt affecting more than 200 plant species, including many economically important plants. However, thus far, the fatty acid biosynthesis pathway of R. solanacearum has not been well studied. In this study, we characterized two forms of 3-keto-ACP synthase III, RsFabH and RsFabW, in R. solanacearum. RsFabH, the homologue of Escherichia coli FabH, encoded by the chromosomal RSc1050 gene, catalyzes the condensation of acetyl-CoA with malonyl-ACP in the initiation steps of fatty acid biosynthesis in vitro. The RsfabH mutant lost de novo fatty acid synthetic ability, and grows in medium containing free fatty acids. RsFabW, a homologue of Pseudomonas aeruginosa PA3286, encoded by a megaplasmid gene, RSp0194, condenses acyl-CoA (C2-CoA to C10-CoA) with malonyl-ACP to produce 3-keto-acyl-ACP in vitro. Although the RsfabW mutant was viable, RsfabW was responsible for RsfabH mutant growth on medium containing free fatty acids. Our results also showed that RsFabW could condense acyl-ACP (C4-ACP to C8-ACP) with malonyl-ACP, to produce 3-keto-acyl-ACP in vitro, which implies that RsFabW plays a special role in fatty acid synthesis of R. solanacearum. All of these data confirm that R. solanacearum not only utilizes acetyl-CoA, but also, utilizes medium-chain acyl-CoAs or acyl-ACPs as primers to initiate fatty acid synthesis.