Affiliation:
1. Institut für Mikrobiologie und Tierseuchen, Tierärztliche Hochschule Hannover, Hannover,1 and
2. Division of Microbiology, GBF-National Research Centre for Biotechnology, Braunschweig,2 Germany
Abstract
ABSTRACT
A novel extracellular mycobacterial enzyme was identified in the ruminant pathogen
Mycobacterium paratuberculosis
. The enzyme was capable of mobilizing iron from different sources such as ferric ammonium citrate, ferritin, and transferrin by reduction of the metal. The purified reductase had a calculated
M
r
of 17,000, was sensitive to proteinase K treatment, and had an isoelectric point of pH 9. Analysis of the amino acid composition revealed glycine, serine, asparagine (or aspartic acid), and glutamine (or glutamic acid) as the most frequently occurring residues. Enzymatic activity was highest at 37°C and between pH 5 and 10. The calculated
K
m
and
V
max
for ferric ammonium citrate were 0.213 mM and 0.345 mM min
−1
mg
−1
, respectively. Using a specific antireductase antibody in immunoelectron microscopy, we were able to detect the enzyme associated with intracellular mycobacteria in naturally
M. paratuberculosis
-infected bovine tissue. We propose that the reductase of
M. paratuberculosis
represents an alternative strategy of mycobacteria to mobilize ferric iron and discuss its potential role in bacterial evasion of intracellular defense mechanisms.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
43 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献