ScrG, a GGDEF-EAL protein, participates in regulating swarming and sticking in Vibrio parahaemolyticus
ScrG, a GGDEF-EAL protein, participates in regulating swarming and sticking in Vibrio parahaemolyticus
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DOI：
10.1128/jb.01510-06
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发表时间：
2007-06-01
影响因子：
3.2
通讯作者：
McCarter, Linda L.
中科院分区：
文献类型：
--
作者：
Kim, Yun-Kyeong;McCarter, Linda L.
在这项工作中，我们描述了一个控制侧生鞭毛基因表达的新基因。该基因编码ScrG，一种含有GGDEF和EAL结构域的蛋白质。这是第二个被确定参与群体运动调控的编码GGDEF - EAL的基因座：第一个先前已被鉴定并命名为scrABC（代表“群体运动和荚膜多糖调控”）。在许多细菌中，含有GGDEF和EAL结构域的蛋白质参与核苷酸信号环二鸟苷酸（c - di - GMP）的合成与降解。scrG的过表达足以在液体中诱导侧生鞭毛基因表达，减少生物膜形成，降低cps基因表达，并抑制ΔscrABC表型。去除其EAL结构域会逆转ScrG的活性，使ScrG转变为群体运动的抑制剂和cps表达的激活剂。scrG的过表达降低了与c - di - GMP标准共迁移的P - 32标记核苷酸斑点的强度，而scrG（ΔEAL）的过表达则增强了该斑点的强度。scrG有缺陷的突变体表现出群体运动和侧生鞭毛蛋白产生以及菌落形态的改变（但游泳运动能力未改变）；此外，两个编码GGDEF - EAL的基因座（scrG和scrABC）的突变对群体运动、侧生鞭毛基因表达、侧生鞭毛蛋白产生和菌落形态产生累积效应。突变体分析支持将ScrG在体内的主要活性归为磷酸二酯酶。这些数据与一个模型相符，在该模型中，多个GGDEF - EAL蛋白质能够影响细胞的核苷酸库：低浓度的c - di - GMP有利于表面运动性，而这种核苷酸的高水平则促进更具粘附性的副溶血性弧菌细胞类型。
In this work, we describe a new gene controlling lateral flagellar gene expression. The gene encodes ScrG, a protein containing GGDEF and EAL domains. This is the second GGDEF-EAL-encoding locus determined to be involved in the regulation of swarming: the first was previously characterized and named scrABC (for "swarming and capsular polysaccharide regulation"). GGDEF and EAL domain-containing proteins participate in the synthesis and degradation of the nucleotide signal cyclic di-GMP (c-di-GMP) in many bacteria. Overexpression of scrG was sufficient to induce lateral flagellar gene expression in liquid, decrease biofilm formation, decrease cps gene expression, and suppress the Delta scrABC phenotype. Removal of its EAL domain reversed ScrG activity, converting ScrG to an inhibitor of swarming and activator of cps expression. Overexpression of scrG decreased the intensity of a P-32-labeled nucleotide spot comigrating with c-di-GMP standard, whereas overexpression of scrG(Delta EAL) enhanced the intensity of the spot. Mutants with defects in scrG showed altered swarming and lateral flagellin production and colony morphology (but not swimming motility); furthermore, mutation of two GGDEF-EAL-encoding loci (scrG and scrABC) produced cumulative effects on swarming, lateral flagellar gene expression, lateral flagellin production and colony morphology. Mutant analysis supports the assignment of the primary in vivo activity of ScrG to acting as a phosphodiesterase. The data are consistent with a model in which multiple GGDEF-EAL proteins can influence the cellular nucleotide pool: a low concentration of c-di-GMP favors surface mobility, whereas high levels of this nucleotide promote a more adhesive Vibrio parahaemolyticus cell type.