Disease relevance of psbA

• High-fluence blue light stimulates transcription from a higher plant chloroplast psbA promoter expressed in a cyanobacterium, Synechococcus (sp. strain PCC7942) [1].

High impact information on psbA

• The reaction center core of photosystem II is composed of two chlorophyll binding proteins, D1 and D2, that are encoded by the chloroplast genes psbA and psbD [2].
• On the other hand, overproduction of AtSig2 enhanced the transcription of psbA gene and trnE operon, but not psbD transcription [3].
• The BLRP was not significantly expressed in cotyledons of light-grown wild-type seedlings, unlike the light-responsive expression of the chloroplast, psbA and rbcL, and nuclear, Lhcb and Chs, genes [4].
• In spite of predominant suppression of expression of rbcL, atpB/E, and psbA at transcription in roots and calli, 16S rRNA levels were decreased because of low RNA stability [5].
• Definite proof that Ely is atrazine-resistant was obtained by sequencing the psbA gene, encoding the D1 protein of photosystem II, revealing a point mutation causing the same amino acid change as found in other atrazine-resistant species [6].

Biological context of psbA

• Their kinetics of accumulation resembled the accumulation of chloroplast psbA and rbcL mRNAs but differed from the accumulation of the nuclear-encoded Lhcb and Chs mRNAs [7].
• In the second nad2 coding region (exons c-e) a pseudo tRNA(Tyr) sequence and a fragment of the plastid psbA gene are located upstream of the trans-spliced exon c. Primer extension analysis identifies RNA 5'-termini within the pseudo-tRNA(Tyr) confirming this sequence to be non-functional [8].
• Based on these findings, we hypothesize that post-transcriptional regulation of psbA gene expression in chloroplasts of vascular plants involves redox-dependent interactions between specific sequences in the 5'UTR and 43- and 30-kDa RNA-binding proteins [9].
• Analysis of Arabidopsis thaliana phytochrome mutants, phyAphyB and hy2, indicated that a distinct blue phototransduction pathway stimulates psbA expression [1].
• The 5' untranslated region (5'UTR) of the psbA mRNA (psbA encodes the PSII reaction center protein, D1) is a key site for RNA-protein interactions in the post-transcriptional regulation of gene expression [9].

Anatomical context of psbA

• Furthermore, transient overexpression of AtSig5 in dark-adapted protoplasts specifically elevated psbD and psbA transcription activities [3].

Other interactions of psbA

• Northern hybridization and RNase protection experiments suggest co-transcription of a minor RNA fraction over the full lengths of psbA and the preceding trnK-UUU gene, but not including downstream trnH sequences [10].
• It contains the conserved genes psbA for the precursor of the D1 reaction-centre protein of photosystem II, trnH for tRNAHis, and rps19' for the 6.8-kDa protein of the small ribosomal subunit [10].
• To identify genetic markers in the Arabidopsis thaliana plastid genome (ptDNA), we amplified and sequenced the rpl2-psbA and rbcL-accD regions in 26 ecotypes [11].

Analytical, diagnostic and therapeutic context of psbA

• Two other PSII genes, psbA (chloroplast-encoded) and psbP (nuclear-encoded), isolated by degenerate primer PCR, display a similar trend in expression [12].

References