title: Annealing of complementary DNA strands above the melting point of the duplex promoted by an archaeal protein.
abstract: One enigma in the biology of hyperthermophilic microorganisms, living near or above 100 degrees C, is how their genomes can be stable and, at the same time, plastic at temperatures above the melting point. The nonspecific DNA-binding protein Sso7d of the hyperthermophilic archaeon Sulfolobus solfataricus is known to protect DNA from thermal denaturation. We report here that Sso7d promotes the renaturation of complementary DNA strands at temperatures above the melting point of the duplex. This novel annealing activity is strictly homology-dependent, and even one mismatch in a stretch of 17 complementary bases severely reduces its efficiency. Since pairing of homologous single strands is a key step in all fundamental processes involving nucleic acids, such as transcription, replication, recombination, and repair, Sso7d is a candidate component of the protein machinery devoted to the coupling of DNA stability to metabolic flexibility at high temperature.
authors.affiliation: Dipartimento di Chimica Organica e Biologica Università di Napoli, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Guagliardi
authors.forename: A
authors.initials: A
authors.lastname: Napoli
authors.forename: M
authors.initials: M
authors.lastname: Rossi
authors.forename: M
authors.initials: M
authors.lastname: Ciaramella
mesh_terms: D019843:Archaeal Proteins; D001426:Bacterial Proteins / Q000378:metabolism*; D018076:DNA, Complementary / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D009691:Nucleic Acid Denaturation; D009692:Nucleic Acid Heteroduplexes; D009695:Nucleic Acid Renaturation; D012689:Sequence Homology, Nucleic Acid; D016944:Sulfolobus / Q000737:chemistry; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009692:Nucleic Acid Heteroduplexes; C093228:Sso7d protein, Sulfolobus