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Titolo:
TWIST, WRITHE, AND GEOMETRY OF A DNA LOOP CONTAINING EQUALLY SPACED COPLANAR BENDS
Autore:
WHITE JH; LUND RA; BAUER WR;
Indirizzi:
UNIV CALIF LOS ANGELES,DEPT MATH LOS ANGELES CA 90024 SUNY STONY BROOK,SCH MED,DEPT MICROBIOL STONY BROOK NY 11794
Titolo Testata:
Biopolymers
fascicolo: 2, volume: 38, anno: 1996,
pagine: 235 - 250
SICI:
0006-3525(1996)38:2<235:TWAGOA>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTEGRATION HOST FACTOR; ESCHERICHIA-COLI; SUPERCOILED DNA; PROTEIN; SITE; DISTANCE; PROMOTER; TRANSCRIPTION; REPRESSION; BINDING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
J.H. White et al., "TWIST, WRITHE, AND GEOMETRY OF A DNA LOOP CONTAINING EQUALLY SPACED COPLANAR BENDS", Biopolymers, 38(2), 1996, pp. 235-250

Abstract

The formation of a topologically closed DNA loop is important in manybiological processes, including the regulation of transcription, recombination, and replication. Modeling DNA as an isotropic elastic rod, we use finite element analysis to show that the dependence of the twist (Delta Tw) and the writhe (Wr) upon the linking number deficit (Delta Lk) is strongly influenced by intrinsic bends. We determine how the geometry of a DNA loop changes as a function of the number of uniformly spaced coplanar 20 degrees bends, oriented so as to open toward the center of the loop. We also calculate the geometry, of DNA lads that are smoothly bent to the same extent. The response of both Delta Tw andWr of a bent DNA to changes in Delta Lk falls into one of three categories, depending upon the number of bends. For a single bend of 20 degrees, Wr increases monotonically with Delta Lk and the change in DeltaTw with distance is constant along the entire DNA axis. For two to ten 20 degrees bends, Wr passes first through a local maximum, then through a local minimum, and finally, increases monotonically as Delta Lk increases. For eleven to eighteen 20 degrees bends, Wr again varies monotonically with Delta Lk. For all numbers of bends greater than two, the Delta Tw per unit length depends upon the distribution of intrinsic bends, being constant between any two adjoining bends but varying with their position relative to the cut location. Accompanying these Delta Lk-associated changes in Wr and Delta Tw per unit length ale characteristic changes in geometry that are specific for each category. The results of these calculations, raise the possibility that intrinsic bends can serve as a control factor in the biological functions associated with loop formation in DNA. (C) 1996 John Wiley & Sons, Inc.

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Documento generato il 12/08/20 alle ore 19:52:56