title: A conserved N-terminal motif in Rad54 is important for chromatin remodeling and homologous strand pairing.
abstract: The Swi2/Snf2-related protein Rad54 is a chromatin remodeling enzyme that is important for homologous strand pairing catalyzed by the eukaryotic recombinase Rad51. The chromatin remodeling and DNA-stimulated ATPase activities of Rad54 are significantly enhanced by Rad51. To investigate the functions of Rad54, we generated and analyzed a series of mutant Rad54 proteins. Notably, the deletion of an N-terminal motif (amino acid residues 2-9), which is identical in Rad54 in Drosophila, mice, and humans, results in a complete loss of chromatin remodeling and strand pairing activities, and partial inhibition of the ATPase activity. In contrast, this conserved N-terminal motif has no apparent effect on the ability of DNA to stimulate the ATPase activity or of Rad51 to enhance the DNA-stimulated ATPase activity. Unexpectedly, as the N terminus of Rad54 is progressively truncated, the mutant proteins regain partial chromatin remodeling activity as well as essentially complete DNA-stimulated ATPase activity, both of which are no longer responsive to Rad51. These findings suggest that the N-terminal region of Rad54 contains an autoinhibitory activity that is relieved by Rad51.
authors.affiliation: Section of Molecular Biology, University of California, San Diego, La Jolla, California 92093-0347, USA.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Alexiadis
authors.forename: Alexandra
authors.initials: A
authors.lastname: Lusser
authors.forename: James T
authors.initials: JT
authors.lastname: Kadonaga
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism*; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004527:Egg Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D009690:Nucleic Acid Conformation; D051135:Rad51 Recombinase; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D017384:Sequence Deletion; D018411:Spodoptera / Q000166:cytology
chemical_list: D002843:Chromatin; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004527:Egg Proteins; D011994:Recombinant Proteins; D004247:DNA; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C108443:okr protein, Drosophila; D004265:DNA Helicases