Expression of genes involved in phycocyanin biosynthesis following recovery of Synechococcus PCC 6301 from nitrogen starvation, and the effect of gabaculine on cpcBa transcript levels

Abstract

The effect of the tetrapyrrole biosynthesis inhibitor gabaculine on the expression of specific genes involved in phycocyanin biosynthesis was investigated in cultures of Synechococcus PCC6301 in nitrogen chlorosis, and during recovery to nitrogen sufficiency. Patterns of transcription of the cpc BA (phycocyanin subunits), hemL (glutamate semialdehyde aminotransferase) and hemB (aminolaevulinate dehydratase) genes were visualised by Northern blotting and gene product formation for cpcBA, hemL and the gene for glu tRNA synthetase were monitored by Western blotting. Inhibition of phycobilin biosynthesis by gabaculine greatly decreased production of phycocyanin protein and of cpcBA transcript, indicating a tight coordination of apoprotein biosynthesis with chromophore supply at the level of transcription. Different patterns of response were observed with the other genes at the level of transcript formation or gene product synthesis.

Phycocyanin, Glutamate semialdehyde aminotransferase, δ-Aminolevulinic acid dehydratase, Gabaculine, Synechococcus PCC 6301

Abbreviations

• ALA

  δ-aminolaevulinic acid

• GSA

  glutamate 1-semialdehyde

• hemB

  ALA-dehydratase gene

• hemL

  GSA-aminotransferase gene

• cpcBA

  phycocyanin β and α subunit gene group