Identification and Subcellular Localization of a Novel Cu,Zn Superoxide Dismutase of Mycobacterium Tuberculosis
Resource
FEBS LETTERS v.439 n.1-2 pp.192-196
Journal
FEBS LETTERS
Journal Volume
v.439
Journal Issue
n.1-2
Pages
192-196
Date Issued
1998
Date
1998
Author(s)
WU, CHUNG-HSUN
TSAI-WU, JYY-JIH
HUANG, YUNG-TZUNG
LIN, CHING-YI
LIOUA, GUNN-GUANG
LEE, FANG-JEN, S
Abstract
Periplasmic copper, zinc superoxide dismutases (Cu,ZnSOD) of several Gram -negative pathogens have been shown to play an important role in protection against exogenous superoxide radicals and in determining virulence of the pathogens. Here we report the cloning and characterization of the sodC gene , encoding Cu,ZnSOD, from the Gram- positive Mycobacterium tuberculosis. The predicted protein sequence contains 240 amino acids with a putative signal peptide at the N- terminus and shows approximately 25% identity to other bacterial sodC. Recombinant proteins of a full-length sodC and a truncated form lacking the putative signal peptide were overexpressed in Escherichia coli and affinity purified . Renatured recombinant M. tuberculosis sodC protein possessed characteristics of a Cu,ZnSOD. Immunoblotting with an antiserum against the recombinant M. tuberculosis Cu, ZnSOD allowed detection of a single polypeptide in the lysate of M. tuberculosis. This polypeptide has a similar size as the recombinant protein without the putative signal peptide indicating that the endogenous Cu,ZnSOD in M. tuberculosis might be processed and secreted. Furthermore, immunogold electron microscopic image showed that Cu,ZnSOD is located in the periphery of M. tuberculosis. The enzymatic activity and subcellular localization of this novel Cu, ZnSOD suggest that it may play a role in determining virulence of M. tuberculosis
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