Linked Life Data

9018042

Source:http://linkedlifedata.com/resource/pubmed/id/9018042

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1997-3-10
pubmed:abstractText
We have identified a mutation (E148A) in T7 RNA polymerase (RNAP) that results in an enzyme which aborts transcription primarily when the nascent RNA achieves a length of 5 nt. This phenomenon is observed at a consensus promoter, but is even more strongly observed at promoters that are altered in the initiation region. Although the abortive product is of a fixed length (5 nt), the positions of the base substitutions in the initiation region that enhance this effect do not appear to be fixed, and we have observed the effect with a variety of initiation-region promoter variants. The phenomenon is also observed during promoter-independent transcription when transcribing a homopolymeric template such as poly(dC). Under conditions where the active site of the RNAP cannot extend beyond the third nucleotide in the template strand and the maximum length of the RNA:DNA hybrid cannot exceed three base-pairs (i.e. when synthesizing oligoG products due to transcript slippage at a promoter that initiates with the sequence +1 GGG...) the mutant RNAP gives rise to a normal spectrum of products 2 to 14 nt in length with no evidence of a block at 5 nt. Neither promoter binding nor promoter melting appears to be involved in this phenotype, as the mutant RNAP binds normally to promoter sequences and the behavior of the enzyme is unaffected by removal of the non-template strand in the initiation region of the promoter or on a supercoiled template. Importantly, the mutant RNAP is defective in binding single strand oligomers of RNA. These results suggest that the affected region of the RNAP may form part of the RNA product binding site and may be involved in the transition from an unstable initiation complex to a stable elongation complex, perhaps by sensing the presence of a nascent RNA and/or RNA:DNA hybrid.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
275-88
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
A mutant T7 RNA polymerase that is defective in RNA binding and blocked in the early stages of transcription.
pubmed:affiliation
Morse Institute of Molecular Genetics, Department of Microbiology and Immunology, SUNY Health Science Center at Brooklyn, NY 11203, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.