Abstract
The photosystem II reaction center chlorophyll protein D2, is encoded by the chloroplast gene psbD. PsbD is transcribed from at least three different promoters, one which is activated by high fluence blue light. Sequences within 130 base pairs (bp) of the psbD blue light-responsive promoter (BLRP) are highly conserved in higher plants. In this study, the structure of the psbD BLRP was analyzed in detail using deletion and site-directed mutagenesis and in vitro transcription. Deletion analysis showed that a 53-bp DNA region of the psbD BLRP, from -57 to -5, was sufficient for transcription in vitro. Mutation of a putative prokaryotic -10 element (TATTCT) located from -7 to -12 inhibited transcription from the psbD BLRP. In contrast, mutation of a putative prokaryotic -35 element, had no influence on transcription. Mutation of a TATATA sequence located between the barley psbA -10 and -35 elements significantly reduced transcription from this promoter. However, site-directed mutation of sequences located between -35 and -10 had no effect on transcription from the psbD BLRP. Transcription from the psbD BLRP was previously shown to require a 22-bp sequence, termed the AAG-box, located between -36 and -57. The AAG-box specifically binds the protein complex AGF. Site-directed mutagenesis identified two different sequence motifs in the AAG-box that are important for transcription in vitro. Based on these results, we propose that positive factors bind to the AAG-box and interact with the chloroplast-encoded RNA polymerase to promote transcription from the psbD BLRP. Transcription from the psbD BLRP is thus similar to type II bacterial promoters that use activating proteins to stimulate transcription. Transcription of the psbD BLRP was approximately 6. 5-fold greater in plastid extracts from illuminated versus dark-grown plants. This suggests that light-induced activation of this promoter in vivo involves factors interacting with the 53-bp psbD BLRP in vitro.
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Claims 7
Claim · model-written summary
A 53-bp psbD promoter region was sufficient for transcription in vitro.
- Taxon
- Barley
.jpg?width=60)
Hordeum vulgaret0 - Gene
- psbD BLRPe0
- Outcome
- transcription in vitroe0
- Value
- 53-bpe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“a 53-bp DNA region of the psbD BLRP, from -57 to -5, was sufficient for transcription in vitro”
t0“Barley”
Claim · model-written summary
Mutation of the -10 element inhibited psbD transcription.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- Mutation of a putative prokaryotic -10 element (TATTCT)e0
- Gene
- psbD BLRPe0
- Outcome
- transcription from the psbD BLRPe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutation of a putative prokaryotic -10 element (TATTCT) located from -7 to -12 inhibited transcription from the psbD BLRP”
t0“Barley”
Claim · model-written summary
Mutation of the -35 element did not influence transcription.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- mutation of a putative prokaryotic -35 elemente0
- Outcome
- transcriptione0
- Direction
- no influencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutation of a putative prokaryotic -35 element, had no influence on transcription”
t0“Barley”
Claim · model-written summary
Mutation of the barley psbA TATATA sequence reduced transcription.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- Mutation of a TATATA sequencee0
- Gene
- barley psbAe0
- Outcome
- transcription from this promotere0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutation of a TATATA sequence located between the barley psbA -10 and -35 elements significantly reduced transcription from this promoter”
Claim · model-written summary
Mutation between -35 and -10 did not affect psbD transcription.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- site-directed mutation of sequences located between -35 and -10e0
- Gene
- psbD BLRPe0
- Outcome
- transcription from the psbD BLRPe0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“site-directed mutation of sequences located between -35 and -10 had no effect on transcription from the psbD BLRP”
t0“Barley”
Claim · model-written summary
Two AAG-box motifs were important for transcription in vitro.
- Taxon
- BarleyHordeum vulgaret0
- Gene
- AAG-boxe0
- Outcome
- transcription in vitroe0
- Value
- twoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two different sequence motifs in the AAG-box that are important for transcription in vitro”
t0“Barley”
Claim · model-written summary
psbD transcription was about 6. 5-fold greater in illuminated plastid extracts.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- illuminatede0
- Outcome
- Transcription of the psbD BLRPe0
- Direction
- greatere0
- Value
- 6. 5-folde0
- Comparator
- dark-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcription of the psbD BLRP was approximately 6. 5-fold greater in plastid extracts from illuminated versus dark-grown plants”
t0“Barley”
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