Zaid Tarrik, Srikumar Trivandrum Sukumaran Nair, Benov Ludmil
Department of Biochemistry, Faculty of Medicine, Kuwait University, Safat 13110, Kuwait.
J Biochem Mol Biol. 2003 Nov 30;36(6):608-10. doi: 10.5483/bmbrep.2003.36.6.608.
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.
大肠杆菌有两种过氧化氢酶，即HPI和HPII。HPI在对数生长期因低浓度过氧化氢而被诱导产生。这种诱导是依赖OxyR的。另一方面，HPII不是由过氧化物诱导的，而是在进入稳定期时被诱导产生。我们在此证明，如果在添加了柠檬酸铁的培养基中培养，与在正常培养基中培养的培养物相比，大肠杆菌表现出更高的HPI过氧化氢酶活性。补充铁对HPII过氧化氢酶没有影响。HPI活性的这种增加不依赖OxyR，并且在Δfur突变体中未观察到。HPI活性增加的生理意义尚不清楚，但似乎编码HPI过氧化氢酶的katG基因是受Fur调控的基因之一。
