Growth of Escherichia coli in iron-enriched medium increases HPI catalase activity.
Escherichia coli has two catalases, HPI and HPII. HPI is induced during logarithmic growth in response to low concentrations of hydrogen peroxide. This induction is OxyR-dependent. On the other hand, HPII is not peroxide-inducible but is induced in entry to the stationary phase. We demonstrate here that E. coli displayed higher HPI catalase activity when compared to the cultures that were grown in a normal medium, if grown in a medium supplemented with iron-citrate. Iron supplementation had no effect on HPII catalase. This increase of HPI activity was OxyR-independent and not observed in a Deltafur mutant. The physiological significance of the increase of HPI activity is unclear, but it appears that the katG gene that codes for HPI catalase is among the genes that are regulated by Fur.
Zaid
Tarrik
T
Department of Biochemistry, Faculty of Medicine, Kuwait University, Safat 13110, Kuwait.
Srikumar
Trivandrum Sukumaran Nair
TS
Benov
Ludmil
L
D002374:Catalase / Q000378:metabolism*; D003470:Culture Media; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development*; D007501:Iron / Q000008:administration & dosage*
D003470:Culture Media; D007501:Iron; D002374:Catalase