Structural Analysis and Insights into the Oligomeric State of an Arginine-Dependent Transcriptional Regulator from Bacillus halodurans

• Published in: PloS one 2016-05, Vol.11 (5), p.e0155396-e0155396
• Main Authors: Park, Young Woo, Kang, Jina, Yeo, Hyun Ku, Lee, Jae Young
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analysis; Arginine; Arginine - metabolism; Bacillus; Bacillus - genetics; Bacillus - metabolism; Bacillus halodurans; Bacillus stearothermophilus; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Binding; Binding sites; Biology and Life Sciences; Biosynthesis; Cloning; Columnar structure; Columns (structural); Crystal structure; Crystallography; Deoxyribonucleic acid; DNA; DNA, Bacterial - metabolism; E coli; Electrophoretic mobility; Escherichia coli; Gene expression; Gene Expression Regulation, Bacterial; Genes; Homology; Hydrophobicity; Influence; Life sciences; Light scattering; Medicine and Health Sciences; Models, Molecular; Oligomerization; Physical Sciences; Physiological aspects; Protein Binding; Protein Multimerization; Proteins; Regulators; Repressor Proteins - chemistry; Repressor Proteins - metabolism; Research and Analysis Methods; Structural analysis; Structural Homology, Protein; Structure-Activity Relationship; Transcription (Genetics); Transcription, Genetic; Tuberculosis; X-ray crystallography
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0155396

The arginine repressor (ArgR) is an arginine-dependent transcription factor that regulates the expression of genes encoding proteins involved in the arginine biosynthesis and catabolic pathways. ArgR is a functional homolog of the arginine-dependent repressor/activator AhrC from Bacillus subtilis, and belongs to the ArgR/AhrC family of transcriptional regulators. In this research, we determined the structure of the ArgR (Bh2777) from Bacillus halodurans at 2.41 Å resolution by X-ray crystallography. The ArgR from B. halodurans appeared to be a trimer in a size exclusion column and in the crystal structure. However, it formed a hexamer in the presence of L-arginine in multi-angle light scattering (MALS) studies, indicating the oligomerization state was dependent on the presence of L-arginine. The trimeric structure showed that the C-terminal domains form the core, which was made by inter-subunit interactions mainly through hydrophobic contacts, while the N-terminal domains containing a winged helix-turn-helix DNA binding motif were arranged around the periphery. The arrangement of trimeric structure in the B. halodurans ArgR was different from those of other ArgR homologs previously reported. We finally showed that the B. halodurans ArgR has an arginine-dependent DNA binding property by an electrophoretic mobility shift assay.