期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 295, 期 33, 页码 11455-11465出版社
ELSEVIER
DOI: 10.1074/jbc.RA120.013981
关键词
calcium; crystal structure; cytochromecnitrite reductase; dissimilatory nitrate reduction to ammonium (DNRA); enzyme catalysis; Geobacter lovleyi; metalloenzyme; NrfA; phylogenetics; nitrogen cycle
资金
- U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0017952, DE-SC0018173]
- U.S. Department of Energy (DOE) [DE-SC0018173, DE-SC0017952] Funding Source: U.S. Department of Energy (DOE)
Cytochromecnitrite reductase (NrfA) catalyzes the reduction of nitrite to ammonium in the dissimilatory nitrate reduction to ammonium (DNRA) pathway, a process that competes with denitrification, conserves nitrogen, and minimizes nutrient loss in soils. The environmental bacteriumGeobacter lovleyihas recently been recognized as a key driver of DNRA in nature, but its enzymatic pathway is still uncharacterized. To address this limitation, here we overexpressed, purified, and characterizedG. lovleyiNrfA. We observed that the enzyme crystallizes as a dimer but remains monomeric in solution. Importantly, its crystal structure at 2.55-angstrom resolution revealed the presence of an arginine residue in the region otherwise occupied by calcium in canonical NrfA enzymes. The presence of EDTA did not affect the activity ofG. lovleyiNrfA, and site-directed mutagenesis of this arginine reduced enzymatic activity to <3% of the WT levels. Phylogenetic analysis revealed four separate emergences of Arg-containing NrfA enzymes. Thus, the Ca2+-independent, Arg-containing NrfA fromG. lovleyirepresents a new subclass of cytochromecnitrite reductase. Most genera from the exclusive clades of Arg-containing NrfA proteins are also represented in clades containing Ca2+-dependent enzymes, suggesting convergent evolution.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据