title: Molecular Mechanism Underlying ATP-Induced Conformational Changes in the Nucleoprotein Filament of Mycobacterium smegmatis RecA.
abstract: RecA plays a central role in bacterial DNA repair, homologous recombination, and restoration of stalled replication forks by virtue of its active extended nucleoprotein filament. Binding of ATP and its subsequent recognition by the carboxamide group of a highly conserved glutamine (Gln196 in MsRecA) have been implicated in the formation of active RecA nucleoprotein filaments. Although the mechanism of ATP-dependent structural transitions in RecA has been proposed on the basis of low-resolution electron microscopic reconstructions, the precise sequence of events that constitute these transitions is poorly understood. On the basis of biochemical and crystallographic analyses of MsRecA variants carrying mutations in highly conserved Gln196 and Arg198 residues, we propose that the disposition of the interprotomer interface is the structural basis of allosteric activation of RecA. Furthermore, this study accounts for the contributions of several conserved amino acids to ATP hydrolysis and to the transition from collapsed to extended filament forms in Mycobacterium smegmatis RecA (MsRecA). In addition to their role in the inactive compressed state, the study reveals a role for Gln196 and Arg198 along with Phe219 in ATP hydrolysis in the active extended nucleoprotein filament. Finally, our data suggest that the primary, but not secondary, nucleotide binding site in MsRecA isomerizes into the ATP binding site present in the extended nucleoprotein filament.
authors.affiliation: Department of Biochemistry, Indian Institute of Science (IISc) , Bangalore 560012, India.|Center of Excellence in Epigenetics, Indian Institute of Science Education and Research (IISER) , Pune 411008, India.
authors.forename: G P
authors.initials: GP
authors.lastname: Manjunath
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) , Pune 411008, India.
authors.forename: Neelesh
authors.initials: N
authors.lastname: Soni
authors.affiliation: Center of Excellence in Epigenetics, Indian Institute of Science Education and Research (IISER) , Pune 411008, India.
authors.forename: Pavana L
authors.initials: PL
authors.lastname: Vaddavalli
authors.affiliation: Center of Excellence in Epigenetics, Indian Institute of Science Education and Research (IISER) , Pune 411008, India.
authors.forename: Dipeshwari J
authors.initials: DJ
authors.lastname: Shewale
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) , Pune 411008, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Madhusudhan
authors.affiliation: Department of Biochemistry, Indian Institute of Science (IISc) , Bangalore 560012, India.
authors.forename: K
authors.initials: K
authors.lastname: Muniyappa
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis; D009698:Nucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D009698:Nucleoproteins; D000255:Adenosine Triphosphate