title: The DnaK chaperone system facilitates 30S ribosomal subunit assembly.
abstract: Functional Escherichia coli 30S ribosomal subunits can be reconstituted in vitro. However, slow kinetics and sharp temperature dependence suggest additional assembly factors are present in vivo. Extract activation of in vitro assembly results in association of DnaK/hsp70 chaperone components with pre-30S particles. Purified DnaK, its cochaperones DnaJ and GrpE, and ATP can facilitate reconstitution of functional 30S subunits under otherwise nonpermissive conditions. A link has been observed between DnaK, 30S subunit components, and ribosome biogenesis in vivo as well as in vitro. These studies reveal a novel role for the DnaK/hsp70 chaperone system, in addition to its well-documented role in protein folding, and suggest that 30S subunit assembly can be facilitated.
authors.affiliation: Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames 50011, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Maki
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Schnobrich
authors.forename: Gloria M
authors.initials: GM
authors.lastname: Culver
mesh_terms: D002499:Centrifugation, Density Gradient; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits; D012335:RNA, Ribosomal / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism*; D013696:Temperature
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D021122:Protein Subunits; D012335:RNA, Ribosomal; C063842:dnaK protein, E coli