Tamegai Hideyuki, Ikeda Eriko, Kato Chiaki, Horikoshi Koki
Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajosui, Tokyo, Japan.
Biosci Biotechnol Biochem. 2007 Aug;71(8):2041-5. doi: 10.1271/bbb.70256. Epub 2007 Aug 7.
The nap gene cluster encoding periplasmic nitrate reductase was identified from Pseudomonas sp. strain MT-1, a deep-sea denitrifier isolated from the Mariana Trench. The ORFs identified were highly homologous with those of Pseudomonas stutzeri, but the cluster included only four ORFs (napDABC), less than those in other organisms. For other bacteria, some additional small ORFs (such as napE, napF, napG, napH, and napK) are found in the nap gene cluster, although their physiological function is still unclear. The soluble fraction of MT-1 grown under denitrifying condition showed significant nitrate reductase activity. This observation suggests that the periplasmic nitrate reductase encoded by the gene cluster identified in this study is functional. The activity was highest when the organism was grown under denitrifying conditions, suggesting that the enzyme participates in dissimilatory nitrite reduction.
从一株从马里亚纳海沟分离出的深海反硝化菌——假单胞菌属MT - 1中，鉴定出了编码周质硝酸盐还原酶的nap基因簇。所鉴定出的开放阅读框（ORF）与斯氏假单胞菌的高度同源，但该基因簇仅包含四个开放阅读框（napDABC），比其他生物体中的要少。对于其他细菌，在nap基因簇中还发现了一些额外的小开放阅读框（如napE、napF、napG、napH和napK），尽管它们的生理功能仍不清楚。在反硝化条件下生长的MT - 1的可溶性部分表现出显著的硝酸盐还原酶活性。这一观察结果表明，本研究中鉴定出的基因簇所编码的周质硝酸盐还原酶具有功能。当该生物体在反硝化条件下生长时，活性最高，这表明该酶参与异化亚硝酸盐还原。
