Escuyer V, Haddad N, Frehel C, Berche P
Unité INSERM U411, Faculté de Médecine Necker-Enfants Malades, Paris, France.
Microb Pathog. 1996 Jan;20(1):41-55. doi: 10.1006/mpat.1996.0004.
Mycobacterium avium is an intracellular pathogen capable of growing inside the phagosomal compartment of macrophages. In this work, we characterized the superoxide dismutase of M. avium, as a putative candidate to resist the oxidative stress. The gene sodA encoding superoxide dismutase (SOD:EC1.15.1.1) from Mycobacterium avium TMC724 was cloned and sequenced. It encodes a 23 kDa protein (207 aminoacids) showing identity with the Mycobacterium leprae SOD (91%) and the M. tuberculosis SOD (83%). This enzyme was functionally expressed in both Escherichia coli and Mycobacterium smegmatis, and identified as a manganese (Mn) SOD on the basis of sequence comparison with other MnSODs from different organisms, and by activity inhibition studies. By indirect immunogold labeling of M. avium with a mAb directed against M. leprae SOD, the enzyme was found to be exposed at the cell surface of M. avium. It was also shown that SOD was released in supernates of M. avium TMV724 during exponential growth, suggesting a role of this enzyme during interactions with the environment. When SOD was expressed in the non-pathogenic M. smegmatis, it was also exposed at the surface of bacteria and released in supernates, but this was not sufficient to protect this recombinant mycobacterium from the killing mechanisms of macrophages.
鸟分枝杆菌是一种能够在巨噬细胞吞噬体隔室内生长的胞内病原体。在这项研究中，我们对鸟分枝杆菌的超氧化物歧化酶进行了表征，将其作为抵抗氧化应激的潜在候选物。对来自鸟分枝杆菌TMC724的编码超氧化物歧化酶（SOD：EC1.15.1.1）的基因sodA进行了克隆和测序。它编码一种23 kDa的蛋白质（207个氨基酸），与麻风分枝杆菌SOD（91%）和结核分枝杆菌SOD（83%）具有同源性。该酶在大肠杆菌和耻垢分枝杆菌中均有功能性表达，并根据与来自不同生物体的其他锰超氧化物歧化酶的序列比较以及活性抑制研究，被鉴定为锰（Mn）超氧化物歧化酶。通过用针对麻风分枝杆菌SOD的单克隆抗体对鸟分枝杆菌进行间接免疫金标记，发现该酶暴露于鸟分枝杆菌的细胞表面。还表明，在指数生长期，SOD在鸟分枝杆菌TMV724的上清液中释放，这表明该酶在与环境相互作用过程中发挥作用。当SOD在非致病性耻垢分枝杆菌中表达时，它也暴露于细菌表面并释放到上清液中，但这不足以保护这种重组分枝杆菌免受巨噬细胞杀伤机制的影响。
