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Titolo:
High-affinity DNA binding of HU protein from the hyperthermophile Thermotoga maritima
Autore:
Grove, A; Lim, L;
Indirizzi:
Louisiana State Univ, Dept Biol Sci, Baton Rouge, LA 70803 USA Louisiana State Univ Baton Rouge LA USA 70803 , Baton Rouge, LA 70803 USA
Titolo Testata:
JOURNAL OF MOLECULAR BIOLOGY
fascicolo: 3, volume: 311, anno: 2001,
pagine: 491 - 502
SICI:
0022-2836(20010817)311:3<491:HDBOHP>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
HISTONE-LIKE PROTEINS; BACTERIUM DEINOCOCCUS-RADIODURANS; ESCHERICHIA-COLI HU; BACILLUS-STEAROTHERMOPHILUS; EXOCYCLIC GROUPS; GENOME SEQUENCE; CRUCIFORM DNA; IHF; TRANSCRIPTION; COMPLEX;
Keywords:
type II DNA-binding protein; DNA bending; thermophile; 5-hydroxymethyluracil; DNA flexibility;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Grove, A Louisiana State Univ, Dept Biol Sci, Baton Rouge, LA 70803 USA Louisiana State Univ Baton Rouge LA USA 70803 ouge, LA 70803 USA
Citazione:
A. Grove e L. Lim, "High-affinity DNA binding of HU protein from the hyperthermophile Thermotoga maritima", J MOL BIOL, 311(3), 2001, pp. 491-502

Abstract

Prokaryotic genomes are compacted by association with small basic proteins, generating what has been termed bacterial chromatin. The ubiquitous DNA-binding protein HU serves this function. DNA-binding properties of HU from the hyperthermophilic eubacterium. Thermotoga maritima are shown here to differ significantly from those characteristic of previously described HU homologs. Electrophoretic mobility shift analyses show that T. maritima HU (TmHU) binds double-stranded DNA with high affinity (K-d = 5.6(+/-0.7) nM for 37 bp DNA). Equivalent affinity is observed between 4 degreesC and 45 degreesC. TmHU has higher affinity for DNA containing a set of 4 nt loops separated by 9 bp (K-d = 1.4(+/-0.3) nM), consistent with its introduction of two DNA kinks. Using DNA probes of varying length, the optimal binding site forTmHU is estimated at 37 bp, in sharp contrast to the 9-10 bp binding site reported for other HU homologs. Alignment of > 60 HU sequences demonstratessignificant sequence conservation: A DNA-intercalating proline residue is almost universally conserved, and it is preceded by arginine and asparaginein most sequences, generating a highly conserved RNP motif; V substitutes for R only in HU from Thermotoga, Thermus and Deinococcus. A fivefold increase in DNA-binding affinity is observed for TmHU in which V is replaced with R (TmHU-V61R; K-d = 1.1(+/-0.2) nM), but a change in the trajectory of DNA flanking the sites of DNA intercalation is inferred from analysis of TmHU-V61R binding to DNA modified with 4 nt loops or with substitutions of 5-hydroxymethyluracil for thymine. Survival in extreme environments places unique demands on protection of genomic DNA from thermal destabilization and onaccess of DNA to the cellular machinery, demands that may be fulfilled by the specific DNA-binding properties of HU and by the fine structure of the bacterial chromatin. (C) 2001 Academic Press.

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Documento generato il 22/09/20 alle ore 13:32:47