Identification of a secreted superoxide dismutase in Mycobacterium avium ssp paratuberculosis

Mycobacterium avium ssp. paratuberculosis (M. paratuberculosis), the causat ive agent of Johne's disease, is an important animal pathogen that has also been implicated in human disease. The major proteins expressed by M. parat uberculosis were analyzed by two-dimensional gel electrophoresis, and a sup eroxide dismutase (Sod) was identified from this protein profile. The M. pa ratuberculosis Sod has a molecular mass of 23 kDa and an isoelectric point of 6.1. Sequence analysis of the corresponding sodA gene from M. paratuberc ulosis indicates that this protein is a manganese-dependent enzyme. We show that the M. paratuberculosis Sod is actively secreted, suggesting that it may elicit a protective cellular immune response in the host during infecti on. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.