Ko J, Splitter G A
Laboratory of Cellular and Molecular Immunology, Department of Animal Health and Biomedical Sciences, University of Wisconsin, 1656 Linden Drive, Madison, WI 53706, USA.
Microb Pathog. 2000 Sep;29(3):191-200. doi: 10.1006/mpat.2000.0373.
To maintain survival in macrophages, Brucella must overcome a hostile phagosomal environment defined as low pH, limited nutrition and low oxygen tension. The specific mechanisms utilized by Brucella to surmount such unfavorable environmental factors in phagosomes are not well understood. In general, to adapt to a change in environmental oxygen tension, bacteria use different terminal oxidases that have different oxygen affinity. To survive in phagosomes where low oxygen tension exists, Brucella, like other bacteria, may require high oxygen affinity terminal oxidases that can accept electrons through a cytochrome bc(1)complex dependent or independent pathway. Using a Brucella abortus cytochrome bc(1)complex deficient mutant, delta fbcF, the requirement for a high oxygen affinity terminal oxidase governed by the cytochrome bc(1)complex dependent pathway was tested. The number of cfu from RAW 264.7 macrophage cells and spleens of BALB/c mice infected with wild-type or the cytochrome bc(1)complex deficient mutant was similar during the course of infection. These results suggest that B. abortus contains no essential terminal oxidase utilized at low oxygen tension in phagosomes requiring the cytochrome bc(1)complex. Alternatively, other branched cytochrome bc(1)complex independent respiratory mechanisms that contain the high oxygen affinity terminal oxidases likely exist to facilitate Brucella survival in phagosomes. This is the first investigation regarding the Brucella respiratory system at the molecular level and the involvement of a respiratory system in Brucella pathogenesis.
为了在巨噬细胞中存活，布鲁氏菌必须克服充满敌意的吞噬体环境，该环境具有低pH值、营养有限和低氧张力的特点。布鲁氏菌用于克服吞噬体中这些不利环境因素的具体机制尚不清楚。一般来说，为了适应环境氧张力的变化，细菌会使用具有不同氧亲和力的不同末端氧化酶。为了在存在低氧张力的吞噬体中存活，布鲁氏菌与其他细菌一样，可能需要高氧亲和力的末端氧化酶，这些酶可以通过依赖或不依赖细胞色素bc(1)复合体的途径接受电子。利用布鲁氏菌流产亚种细胞色素bc(1)复合体缺陷突变体delta fbcF，测试了由细胞色素bc(1)复合体依赖途径控制的高氧亲和力末端氧化酶的需求。在感染过程中，感染野生型或细胞色素bc(1)复合体缺陷突变体的RAW 264.7巨噬细胞和BALB/c小鼠脾脏中的cfu数量相似。这些结果表明，布鲁氏菌流产亚种在需要细胞色素bc(1)复合体的低氧张力吞噬体中不含有必需的末端氧化酶。或者，可能存在其他含有高氧亲和力末端氧化酶的、不依赖细胞色素bc(1)复合体的分支呼吸机制，以促进布鲁氏菌在吞噬体中的存活。这是关于布鲁氏菌呼吸系统分子水平以及呼吸系统在布鲁氏菌致病过程中作用的首次研究。
