Huston Wilhelmina M, Harhangi Harry R, Leech Andrew P, Butler Clive S, Jetten Mike S M, Op den Camp Huub J M, Moir James W B
Department of Biology (Area 10), University of York, Heslington, York YO10 5YW, UK.
Protein Expr Purif. 2007 Jan;51(1):28-33. doi: 10.1016/j.pep.2006.06.026. Epub 2006 Sep 9.
The purification of small quantities of a major small c-type cytochrome from the anammox bacterium Kuenenia stuttgartiensis has recently been reported. In order to characterise this protein further we have expressed the gene encoding this cytochrome in Escherichia coli and have purified the protein to homogeneity. The protein is directed to the E. coli periplasm using its native signal sequence suggesting that it may be translocated via a Sec-type system in K. stuttgartiensis. The cytochrome has the visible spectroscopic properties typical of a low-spin c-type cytochrome, but these spectroscopic features broaden in high salt solutions. The oxidised cytochrome was able to bind the ligands NO and cyanide. A redox potential of +230 mV suggests that the protein is suitable to act as an electron carrier protein that may be involved in the respiratory chain between hydrazine oxidation and the reduction of nitrite. The predicted protein sequence for the cytochrome suggests it to be a predominantly alpha-helical protein, and this is supported by circular dichroism.
最近有报道称，已从厌氧氨氧化细菌斯氏库氏菌中纯化出少量主要的小c型细胞色素。为了进一步表征这种蛋白质，我们在大肠杆菌中表达了编码该细胞色素的基因，并将该蛋白质纯化至同质。利用其天然信号序列将该蛋白质导向大肠杆菌周质，这表明它可能通过斯氏库氏菌中的Sec型系统进行转运。该细胞色素具有低自旋c型细胞色素典型的可见光谱特性，但这些光谱特征在高盐溶液中会变宽。氧化型细胞色素能够结合配体NO和氰化物。+230 mV的氧化还原电位表明该蛋白质适合作为电子载体蛋白，可能参与肼氧化和亚硝酸盐还原之间的呼吸链。细胞色素的预测蛋白质序列表明它主要是一种α螺旋蛋白，圆二色性实验也证实了这一点。
