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Titolo:
Model of a LexA repressor dimer bound to recA operator
Autore:
Chattopadhyaya, R; Ghosh, K; Namboodiri, VMH;
Indirizzi:
Bose Inst, Dept Biochem, Calcutta 700054, W Bengal, India Bose Inst Calcutta W Bengal India 700054 Calcutta 700054, W Bengal, India
Titolo Testata:
JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS
fascicolo: 2, volume: 18, anno: 2000,
pagine: 181 - 197
SICI:
0739-1102(200010)18:2<181:MOALRD>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
DNA-BINDING DOMAIN; AMINO-TERMINAL DOMAIN; ESCHERICHIA-COLI; SOS MUTAGENESIS; UMUD' PROTEIN; INTACT UMUD; CLEAVAGE; AUTODIGESTION; DIMERIZATION; GENE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Chattopadhyaya, R Bose Inst, Dept Biochem, Calcutta 700054, W Bengal, India Bose Inst Calcutta W Bengal India 700054 Bengal, India
Citazione:
R. Chattopadhyaya et al., "Model of a LexA repressor dimer bound to recA operator", J BIO STRUC, 18(2), 2000, pp. 181-197

Abstract

A complete three dimensional model (RCSB000408; PDB code 1qaa) for the LexA repressor dimer bound to the recA operator site consistent with relevant biochemical and biophysical data for the repressor is proposed. A model of interaction of the N-terminal operator binding domain 1-72 with the operator was available. We have modelled residues 106-202 of LexA on the basis of the crystal structure of a homologous protein, UmuD'. Residues 70-105 have been modelled by us, residues 70-77 comprising the real hinge, followed by a beta -strand and an alpha -helix, both interacting with the rest of the C-domain. The preexponential Arrhenius factor for the LexA autocleavage is shown to be similar to 10(9) s(-1) at 298K whereas the exponential factor issimilar to2 x 10(-12), demanding that the autocleavage site is quite closeto the catalytic site but reaction is slow due to an activation energy barrier We propose that in the operator bound form, Ala 84- Gly 85 is about 7-10 Angstrom from the catalytic groups, but the reaction does not occur as the geometry is nor suitable for a nucleophilic attack from Ser 119 O gamma,since Pro 87 is held in the cis conformation. When pH is elevated or underthe action of activated RecA, cleavage may occur following a cis --> transisomerization at Pro 87 and/or a rotation of the region beta (9)-beta (10)about beta (7)-beta (8) following the disruption of two hydrogen bonds. Weshow that the C-C interaction comprises the approach of two negatively charged surfaces neutralized by sodium ions, the C-domains of the monomers making a new beta barrel at the interface burying 710 Angstrom (2) of total surface area of each monomer.

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Documento generato il 04/06/20 alle ore 01:51:00