Journal Article

The<i>psbO</i> Gene for 33-kDa Precursor Polypeptide of the Oxygen-Evolving Complex in <i>Arabidopsis thaliana</i> — Nucleotide Sequence and Control of its Expression

Pradeep K. Jain, Anju Kochhar, Jitendra P. Khurana and Akhilesh K. Tyagi

in DNA Research

Published on behalf of Kazusa DNA Research Institute

Volume 5, issue 4, pages 221-228
Published in print January 1998 | ISSN: 1340-2838
Published online January 1998 | e-ISSN: 1756-1663 | DOI: http://dx.doi.org/10.1093/dnares/5.4.221

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The 33-kDa polypeptide of the oxygen-evolving complex of photosystem II is nuclear-encoded. The single psbO gene of Arabidopsis thaliana, as suggested by Southern hybridization, has been isolated from the genomic library and sequenced. The sequence analysis has revealed that the psbO gene harbors two introns and encodes a precursor polypeptide of 332 amino acid residues; the first 85 amino acid residues represent the transit peptide and the following 247 amino acids constitute the mature polypeptide. The hydrophilic nature of the 33-kDa protein is confirmed by the presence of 27% charged residues. Northern analysis of the total RNA from Arabidopsis indicates that a 1.2-kb transcript represents the psbO gene. It is expressed in a tissue-specific manner — the steady-state transcript levels being highest in the leaves and virtually undetectable in the roots. Also, expression of the psbO gene is development-dependent and regulated by light in young Arabidopsis seedlings. In a constitutively photomorphogenic mutant of Arabidopsis, pho2 (plumular hook open 2), the psbO gene is de-repressed in young, dark-grown seedlings, resulting in increased transcript abundance compared to the wild-type. These studies, thus, define the influence of at least one regulatory component for psbO expression.

Keywords: Arabidopsis thaliana; gene expression; oxygen-evolving complex; photomorphogenic mutant; psbO gene

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Subjects: Genetics and Genomics

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