Chou F L, Chou H C, Lin Y S, Yang B Y, Lin N T, Weng S F, Tseng Y H
Department of Botany and Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Biochem Biophys Res Commun. 1997 Apr 7;233(1):265-9. doi: 10.1006/bbrc.1997.6365.
A cloned 4.1-kb EcoRI fragment from Xanthomonas campestris pv. campestris was previously shown to complement the non-mucoid mutant P22 and increase xanthan gum production after being transformed into the wild-type strain Xc17. The gene responsible for these effects was identified, sequenced, and shown to be the gumD gene which has previously been proposed to encode glucose transferase activity, an enzyme required for adding the first glucose residue to the isoprenoid glycosyl carrier lipid during xanthan synthesis. A gumD mutant, isolated from Xc17 by gene replacement, was shown to possess altered pigment xanthomonadin profiles and exhibit reduced virulence in causing black rot in broccoli. This study appears to be the first to demonstrate that interruption of a gene required for xanthan synthesis can lead to reduced virulence of X. campestris.
先前已证明，来自野油菜黄单胞菌野油菜致病变种的一个克隆的4.1-kb EcoRI片段，在转化到野生型菌株Xc17中后，能够互补非黏液突变体P22并增加黄原胶的产量。鉴定了负责这些效应的基因，对其进行了测序，并证明它是gumD基因，之前有人提出该基因编码葡萄糖转移酶活性，在黄原胶合成过程中，该酶是向类异戊二烯糖基载体脂质添加第一个葡萄糖残基所必需的。通过基因置换从Xc17中分离出的一个gumD突变体，显示出具有改变的色素黄单胞菌素谱，并且在引起西兰花黑腐病方面表现出降低的毒力。这项研究似乎是首次证明，黄原胶合成所需基因的中断会导致野油菜黄单胞菌的毒力降低。
