Communication between subunits within an archaeal clamp-loader complex.
We have investigated the communication between subunits in replication factor C (RFC) from Archaeoglobus fulgidus. Mutation of the proposed arginine finger in the small subunits results in a complex that can still bind ATP but has impaired clamp-loading activity, a process that normally only requires binding of nucleotide. The small subunit alone forms a hexameric ring that is six-fold symmetric in the absence of ATP. However, this symmetry is broken when the nucleotide is bound to the complex. A conformational change associated with nucleotide binding may relate to the opening of PCNA rings by RFC during the loading reaction. The structures also reveal the importance of the N-terminal helix of each subunit at the ATP-binding site. Analysis of mutant protein complexes containing subunits lacking this N-terminal helix reveals key distinct regulatory roles during clamp loading that are different for the large and small subunits in the RFC complex.
Seybert
Anja
A
Clare Hall Laboratories, Cancer Research UK, London Research Institute, South Mimms Potters Bar, Herts, UK.
Singleton
Martin R
MR
Cook
Nicola
N
Hall
David R
DR
Wigley
Dale B
DB
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019611:Archaeoglobus fulgidus / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism; D004261:DNA Replication / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D001120:Arginine