Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Consejo de Investigaciones Científicas y Técnicas, Universidad Nacional de San Martín (CONICET-UNSAM), Av. Gral. Paz 5445, Buenos Aires, Argentina.
Microb Pathog. 2012 Jan;52(1):31-40. doi: 10.1016/j.micpath.2011.09.008. Epub 2011 Oct 2.
Numerous chromosomal virulence genes (chv) have been shown to play an important role in the ability of Agrobacterium tumefaciens to transform plants. The A. tumefaciens chvH gene encodes a protein similar in sequence to the Escherichia coli elongation factor P (EF-P). In A. tumefaciens this factor is required for tumor formation and for full expression of the vir genes, exerting its activity at a post-transcriptional level. Cross-complementation assays suggest that the chvH gene and the efp gene of E. coli are functionally homologous. We have cloned and characterized the efp homolog gene in Brucella abortus which has 45% identity to A. tumefaciens chvH and 35% identity to E. coli efp. The gene complemented detergent sensitivity and virulence in the chvH A. tumefaciens mutant, suggesting that both genes are functionally homologous; the growth rate in complex medium also increased to wild type levels. An efp mutant in B. abortus 2308 grew slower in complex media and showed more sensitivity to detergents. Infection assays in J774 macrophage like cells revealed no significant differences between the wild type and the efp mutant strains. The recovery of this mutant from spleens of inoculated mice was equivalent compared to that of the parental strain suggesting that B. abortus efp is not required for virulence in an animal model. However the efp mutant revealed significant differences at 1 h-4 h post-infection in HeLa infection assays compared to the wild type strain, indicating that cellular internalization was affected in non-professional phagocytes. Double immunofluorescence assays for detecting extracellular and intracellular bacteria, demonstrated that the mutant attaches to HeLa cells as the wild type but is deficient in the internalization process, thus indicating that efp is involved in the penetration of Brucella in non-professional phagocytes.
许多染色体毒力基因（chv）已被证明在根癌农杆菌转化植物的能力中发挥重要作用。根癌农杆菌 chvH 基因编码的蛋白质在序列上与大肠杆菌延伸因子 P（EF-P）相似。在根癌农杆菌中，该因子是肿瘤形成和 vir 基因充分表达所必需的，在转录后水平发挥其活性。交叉互补测定表明，chvH 基因和大肠杆菌的 efp 基因在功能上是同源的。我们已经克隆和鉴定了流产布鲁氏菌 efp 同源基因，它与根癌农杆菌 chvH 的同源性为 45%，与大肠杆菌 efp 的同源性为 35%。该基因互补了 chvH 根癌农杆菌突变体的去污剂敏感性和毒力，表明这两个基因在功能上是同源的；在复杂培养基中的生长速度也增加到野生型水平。流产布鲁氏菌 2308 的 efp 突变体在复杂培养基中的生长速度较慢，对去污剂更敏感。在 J774 巨噬样细胞感染实验中，野生型和 efp 突变菌株之间没有明显差异。与亲本菌株相比，从接种小鼠的脾脏中回收该突变体的效率相当，表明在动物模型中，流产布鲁氏菌 efp 不是毒力所必需的。然而，与野生型菌株相比，efp 突变体在 HeLa 感染实验中 1 小时至 4 小时的感染后显示出显著差异，表明在非专业吞噬细胞中细胞内化受到影响。用于检测细胞外和细胞内细菌的双免疫荧光测定表明，突变体与 HeLa 细胞附着的方式与野生型相同，但在内化过程中存在缺陷，因此表明 efp 参与了布鲁氏菌在非专业吞噬细胞中的穿透。
