title: ATP-dependent aggregation of single-stranded DNA by a bacterial SMC homodimer.
abstract: SMC (structural maintenance of chromosomes) proteins are putative ATPases that are highly conserved among Bacteria, Archaea and Eucarya. Eukaryotic SMC proteins are implicated in a diverse range of chromosome dynamics including chromosome condensation, dosage compensation and recombinational repair. In eukaryotes, two different SMC proteins form a heterodimer, which in turn acts as the core component of a large protein complex. Despite recent progress, no ATP-dependent activity has been found in individual SMC subunits. We report here the first biochemical characterization of a bacterial SMC protein from Bacillus subtilis. Unlike eukaryotic versions, the B.subtilis SMC protein (BsSMC) is a simple homodimer with no associated subunits. It binds preferentially to single-stranded DNA (ssDNA) and has a ssDNA-stimulated ATPase activity. In the presence of ATP, BsSMC forms large nucleoprotein aggregates in a ssDNA-specific manner. Proteolytic cleavage of BsSMC is changed upon binding to ATP and ssDNA. The energy-dependent aggregation of ssDNA might represent a primitive type of chromosome condensation that occurs during segregation of bacterial chromosomes.
authors.affiliation: Cold Spring Harbor Laboratory, PO Box 100, Cold Spring Harbor, NY 11724, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: T
authors.initials: T
authors.lastname: Hirano
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D010450:Endopeptidases / Q000378:metabolism; D008969:Molecular Sequence Data
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000255:Adenosine Triphosphate; D010450:Endopeptidases; D000251:Adenosine Triphosphatases