title: Hexameric ring structure of the N-terminal domain of Mycobacterium tuberculosis DnaB helicase.
abstract: Hexameric DnaB helicase unwinds the DNA double helix during replication of genetic material in bacteria. DnaB is an essential bacterial protein; therefore, it is an important potential target for antibacterial drug discovery. We report a crystal structure of the N-terminal region of DnaB from the pathogen Mycobacterium tuberculosis (MtDnaBn), determined at 2.0 A resolution. This structure provides atomic resolution details of formation of the hexameric ring of DnaB by two distinct interfaces. An extensive hydrophobic interface stabilizes a dimer of MtDnaBn by forming a four-helix bundle. The other, less extensive, interface is formed between the dimers, connecting three of them into a hexameric ring. On the basis of crystal packing interactions between MtDnaBn rings, we suggest a model of a helicase-primase complex that explains previously observed effects of DnaB mutations on DNA priming.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Tapan
authors.initials: T
authors.lastname: Biswas
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Tsodikov
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D019915:DNA Primase / Q000737:chemistry; D053488:DnaB Helicases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D019915:DNA Primase; D053488:DnaB Helicases