Linked Life Data

12172808

Source:http://linkedlifedata.com/resource/pubmed/id/12172808

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2002-8-12
pubmed:abstractText
Transcription of the psbA2 gene in the unicellular photosynthetic cyanobacterium Microcystis aeruginosa K-81 is modulated by light and follows a circadian rhythm. In this study, we further characterized psbA transcription using a series of 5'-upstream deletions and mutant promoters which were tested in both photosynthetic and non-photosynthetic bacteria. Specific psbA2 transcripts were obtained from a minimal promoter sequence (-38/+14) with Escherichia coli RNA polymerases (RNAPs) both in vivo and in vitro, indicating the presence of a common regulatory mechanism for basal transcription. A DNase I footprinting assay showed that the E. coli RNAP, which is structurally similar to that of cyanobacteria, specifically binds to a large segment (from -115 to +23) of the sequence upstream of psbA2. In cyanobacteria, the -10 sequence (TAGTAT), but not the -35 motif (TTTACA), is essential for basal transcription by homologous and heterologous RNAPs that contain the major sigma factor. Each of the conserved thymidine nucleotides at positions -12 and -7 (underlined above) was essential, and both an insertion and a deletion in the spacer region of the promoter caused reductions in transcription. RNAP was able to bind to a mutant promoter lacking the -10 sequence, though this did not actually lead to transcription. Interestingly, a high level of arrhythmic circadian transcription was observed in mutants lacking the -35 region. In contrast, a mutation in the AU-box mutation, which controls the stability of the psbA2 mRNA, did not affect the circadian pattern of transcription. These findings demonstrate that light-dependent psbA2 expression is controlled at the transcriptional and post-transcriptional levels, whereas the circadian pattern of expression is regulated at the transcriptional level.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
1617-4615
pubmed:author
pubmed:issnType
Print
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
684-94
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
The 5'-upstream cis-acting sequences of a cyanobacterial psbA gene: analysis of their roles in basal, light-dependent and circadian transcription.
pubmed:affiliation
Laboratory of Molecular Genetics, School of Agriculture, Ibaraki University, Ami-machi, Inashiki-gun, Ibaraki 300-0332, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't