Berducci Giovanni, Mazzetti Anna Paola, Rotilio Giuseppe, Battistoni Andrea
Dipartimento di Biologia, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy.
FEBS Lett. 2004 Jul 2;569(1-3):289-92. doi: 10.1016/j.febslet.2004.06.008.
We have investigated the availability of zinc in the periplasmic space of Escherichia coli using a mutant Cu,Zn superoxide dismutase whose dimerization is triggered by zinc binding. This mutant enzyme accumulates in the monomeric form when wild type cells are grown in minimal medium, but assembles in the dimeric form when it is produced in the same medium by a mutant strain lacking the periplasmic zinc metallochaperone ZnuA. These results indicate that periplasmic zinc-containing proteins compete for metal binding when bacteria grow in environments where this element is present in traces. The effective ZnuA ability to sequester the available zinc ions from the periplasm suggests that zinc-containing cytoplasmic proteins are more important for bacterial viability than the periplasmic ones.
我们利用一种突变型铜锌超氧化物歧化酶研究了大肠杆菌周质空间中锌的可用性，该酶的二聚化由锌结合触发。当野生型细胞在基本培养基中生长时，这种突变酶以单体形式积累，但当它由缺乏周质锌金属伴侣蛋白ZnuA的突变菌株在相同培养基中产生时，则组装成二聚体形式。这些结果表明，当细菌在痕量存在该元素的环境中生长时，周质含锌蛋白会竞争金属结合。ZnuA从周质中螯合可用锌离子的有效能力表明，含锌的细胞质蛋白对细菌生存力比周质蛋白更重要。
