Bacillus subtilis HmoB is a heme oxygenase with a novel structure

Abstract

Iron availability is limited in the environment and mostbacteria have developed a system to acquire iron from hosthemoproteins. Heme oxygenase plays an important role bydegrading heme group and releasing the essential nutrientiron. The structure of Bacillus subtilis HmoB was determinedto 2.0 Å resolution. B. subtilis HmoB contains a typicalantibiotic biosynthesis monooxygenase (ABM) domain thatspans from 71 to 146 residues and belongs to the IsdG familyheme oxygenases. Comparison of HmoB and IsdG familyproteins showed that the C-terminal region of HmoB hassimilar sequence and structure to IsdG family proteins andcontains conserved critical residues for heme degradation.However, HmoB is distinct from other IsdG family proteins inthat HmoB is about 60 amino acids longer in the N-terminusand does not form a dimer whereas previously studied IsdGfamily heme oxygenases form functional homodimers.Interestingly, the structure of monomeric HmoB resembles thedimeric structure of IsdG family proteins. Hence, B. subtilisHmoB is a heme oxygenase with a novel structural feature.[BMB reports 2012; 45(4): 239-241]

Keywords

• Antibiotic biosynthesis domain
• Crystallography
• Ferredoxin-fold
• Heme oxygenase