Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
DNA helicase RepA: Cooperative ATPase activity and binding of nucleotides
Autore:
Xu, H; Frank, J; Niedenzu, T; Saenger, W;
Indirizzi:
Free Univ Berlin, Inst Kristallog, D-14195 Berlin, Germany Free Univ Berlin Berlin Germany D-14195 stallog, D-14195 Berlin, Germany Max Planck Gesell, Fritz Haber Inst, D-14195 Berlin, Germany Max Planck Gesell Berlin Germany D-14195 r Inst, D-14195 Berlin, Germany
Titolo Testata:
BIOCHEMISTRY
fascicolo: 40, volume: 39, anno: 2000,
pagine: 12225 - 12233
SICI:
0006-2960(20001010)39:40<12225:DHRCAA>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
TERMINATION FACTOR-RHO; SINGLE-STRANDED-DNA; ESCHERICHIA-COLI; PLASMID RSF1010; CRYSTAL-STRUCTURE; PROTEIN; GENE; BACTERIOPHAGE-T7; HYDROLYSIS; MECHANISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Saenger, W Free Univ Berlin, Inst Kristallog, Takustr 6, D-14195 Berlin, Germany Free Univ Berlin Takustr 6 Berlin Germany D-14195 lin, Germany
Citazione:
H. Xu et al., "DNA helicase RepA: Cooperative ATPase activity and binding of nucleotides", BIOCHEM, 39(40), 2000, pp. 12225-12233

Abstract

The steady-state kinetic parameters of the ATPase activity of the homohexameric DNA helicase RepA and the binding of the fluorescent analogue epsilonADP to RepA have been studied. ssDNA stimulates RepA ATPase activity optimally at acidic pH 5.3-6.0. The sigmoidal kinetic curves in both the absenceand presence of ssDNA show strong positive cooperativity for ATP hydrolysis, with oligonucleotides longer than 10mer optimal for ssDNA-stimulated ATPase activity. Fluorescence titrations show that, at 25 degrees C and in theabsence of DNA, the binding of epsilon ADP to RepA is biphasic with three high (K-1 = 1.54 x 10(6) M-1) and three low (K-2 = 4.71 x 10(4) M-1) affinity binding sites differing by 30-40-fold in binding constants. In the absence of cofactors, RepA melts cooperatively at T-m= 65.8 +/- 0.1 degrees C and is more stable in the presence of ATP gamma S, T-m = 68.1 +/- 0.2 degreesC (Delta Delta G 0.95 kcal/mol), than in the presence of ADP, T-m = 66.5 +/- 0.1 degrees C (Delta Delta G 0.29 kcal/mol), indicating that the additional phosphate group in ATP gamma S has a significant influence on RepA structure. A model is proposed in which individual subunits of RepA sequentially and cooperatively perform a multistep ATP hydrolytic cycle.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 07:01:16