title: Mitochondrial Lon of Saccharomyces cerevisiae is a ring-shaped protease with seven flexible subunits.
abstract: Lon (or La) is a soluble, homooligomeric ATP-dependent protease. Mass determination and cryoelectron microscopy of pure mitochondrial Lon from Saccharomyces cerevisiae identify Lon as a flexible ring-shaped heptamer. In the presence of ATP or 5'-adenylylimidodiphosphate, most of the rings are symmetric and resemble other ATP-driven machines that mediate folding and degradation of proteins. In the absence of nucleotides, most of the rings are distorted, with two adjacent subunits forming leg-like protrusions. These results suggest that asymmetric conformational changes serve to power processive unfolding and translocation of substrates to the active site of the Lon protease.
authors.affiliation: M. E. Müller Institut, Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. stahlbergh@ubaclu.unibas.ch
authors.forename: H
authors.initials: H
authors.lastname: Stahlberg
authors.forename: E
authors.initials: E
authors.lastname: Kutejová
authors.forename: K
authors.initials: K
authors.lastname: Suda
authors.forename: B
authors.initials: B
authors.lastname: Wolpensinger
authors.forename: A
authors.initials: A
authors.lastname: Lustig
authors.forename: G
authors.initials: G
authors.lastname: Schatz
authors.forename: A
authors.initials: A
authors.lastname: Engel
authors.forename: C K
authors.initials: CK
authors.lastname: Suzuki
mesh_terms: D049069:ATP-Dependent Proteases; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D008928:Mitochondria / Q000201:enzymology*; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000648:ultrastructure; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases