3gpn
Structure of the non-trimeric form of the E113G PCNA mutant protein
Structural highlights
FunctionPCNA_YEAST This protein is an auxiliary protein of DNA polymerase delta and is involved in the control of eukaryotic DNA replication by increasing the polymerase's processibility during elongation of the leading strand. Involved in DNA repair.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedEukaryotic proliferating cell nuclear antigen (PCNA) is an essential replication accessory factor that interacts with a variety of proteins involved in DNA replication and repair. Each monomer of PCNA has an N-terminal domain A and a C-terminal domain B. In the structure of the wild-type PCNA protein, domain A of one monomer interacts with domain B of a neighboring monomer to form a ring-shaped trimer. Glu113 is a conserved residue at the subunit interface in domain A. Two distinct X-ray crystal structures have been determined of a mutant form of PCNA with a substitution at this position (E113G) that has previously been studied because of its effect on translesion synthesis. The first structure was the expected ring-shaped trimer. The second structure was an unanticipated nontrimeric form of the protein. In this nontrimeric form, domain A of one PCNA monomer interacts with domain A of a neighboring monomer, while domain B of this monomer interacts with domain B of a different neighboring monomer. The B-B interface is stabilized by an antiparallel beta-sheet and appears to be structurally similar to the A-B interface observed in the trimeric form of PCNA. The A-A interface, in contrast, is primarily stabilized by hydrophobic interactions. Because the E113G substitution is located on this hydrophobic surface, the A-A interface should be less favorable in the case of the wild-type protein. This suggests that the side chain of Glu113 promotes trimer formation by destabilizing these possible alternate subunit interactions. A charged residue at the subunit interface of PCNA promotes trimer formation by destabilizing alternate subunit interactions.,Freudenthal BD, Gakhar L, Ramaswamy S, Washington MT Acta Crystallogr D Biol Crystallogr. 2009 Jun;65(Pt 6):560-6. Epub 2009, May 15. PMID:19465770[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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