Characterization of a Dimeric Arginase From Zymomonas mobilis ZM4

• Published in: Frontiers in microbiology Vol. 10; p. 2755
• Main Authors: Hwangbo, Seung-A, Kim, Ji-Won, Jung, Sun-Ju, Jin, Kyeong Sik, Lee, Jie-Oh, Kim, Jeong-Sun, Park, Suk-Youl
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 26.11.2019
• Subjects: ARG; arginase; arginine; dimer; GGDCS motif; Microbiology; structure; arginine; ARG; arginase; structure; dimer; GGDCS motif
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2019.02755

Many organisms have genes to protect themselves from toxic conditions such as high ethanol and/or ammonia concentrations. When a high ethanol condition is induced to ZM4, a representative ethanologenic organism, this bacterium overexpresses several genes to overcome this ethanol stress. Among them, we characterized a gene product annotated as an arginase (zmARG) from ZM4. Even though all of the arginase-determining sequence motifs are not strictly conserved in zmARG, this enzyme converts L-arginine to urea and L-ornithine in the presence of a divalent manganese ion. The revealed high-resolution crystal structure of zmARG shows that it has a typical globular α/β arginase fold with a protruded C-terminal helix. Two zinc ions reside in the active site, where one metal ion is penta-coordinated and the other has six ligands, discerning this zmARG from the reported arginases with two hexa-liganded metal ions. zmARG forms a dimeric structure in solution as well as in the crystalline state. The dimeric assembly of zmARG is formed mainly by interaction formed between the C-terminal α-helix of one molecule and the α/β hydrolase fold of another molecule. The presented findings demonstrate the first reported dimeric arginase formed by the C-terminal tail and has two metal ions coordinated by different number of ligands.