Department of Environmental Science, Policy, and Management, University of California, Berkeley 94720, USA.
Mol Plant Microbe Interact. 2012 Apr;25(4):453-62. doi: 10.1094/MPMI-03-11-0074.
In Xylella fastidiosa the fatty acid signal molecule diffusible signaling factor (DSF) is produced and sensed by components of the regulation of pathogenicity factors (rpf) cluster; lack of DSF production in RpfF mutants results in a non-vector-transmissible phenotype yet cells are hypervirulent to grape. rpfB has not been characterized in Xylella fastidiosa, although its homolog has been suggested to be required for DSF synthesis in Xanthomonas campestris pv. campestris. We show that RpfB is involved in DSF processing in both Xylella fastidiosa and Xanthomonas campestris, affecting the profile of DSF-like fatty acids observed in thin-layer chromatography. Although three fatty acids whose production is dependent on RpfF were detected in Xylella fastidiosa and Xanthomonas campestris wild-type strains, their respective rpfB mutants accumulated primarily one chemical species. Although no quantifiable effect of rpfB on plant colonization by Xylella fastidiosa was found, insect colonization and transmission was reduced. Thus, RpfB apparently is involved in DSF processing, and like Xanthomonas campestris, Xylella fastidiosa also produces multiple DSF molecules. It is possible that Xylella fastidiosa coordinates host vector and plant colonization by varying the proportions of different forms of DSF signals via RpfB.
在韧皮部坏死杆菌中，脂肪酸信号分子可扩散信号因子（DSF）由致病性因子调控（rpf）簇的组成部分产生和感知；RpfF 突变体中缺乏 DSF 产生导致非载体可传播的表型，但细胞对葡萄具有超毒力。rpfB 在韧皮部坏死杆菌中尚未被表征，尽管其同源物被认为是黄单胞菌野油菜致病变种中 DSF 合成所必需的。我们表明 RpfB 参与了韧皮部坏死杆菌和黄单胞菌的 DSF 加工，影响了在薄层色谱中观察到的 DSF 样脂肪酸的图谱。尽管在韧皮部坏死杆菌和黄单胞菌野生型菌株中检测到三种依赖于 RpfF 产生的脂肪酸，但它们各自的 rpfB 突变体主要积累一种化学物质。尽管没有发现 rpfB 对韧皮部坏死杆菌植物定殖有可量化的影响，但昆虫定殖和传播减少了。因此，RpfB 显然参与了 DSF 的加工，并且与黄单胞菌一样，韧皮部坏死杆菌也产生多种 DSF 分子。韧皮部坏死杆菌可能通过 RpfB 改变不同形式的 DSF 信号的比例来协调宿主-载体和植物的定殖。
