Cloning and differential expression analysis of a new rbcS gene from Lemna gibba

Abstract

A novel Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit gene (named ssu4d) was cloned from Lemna gibba by a novel chromosome walking technology. The full-length of ssu4d cDNA (named ssu4dc), contained a 522 bp open reading frame encoding a protein of 174 amino acids. Sequence analysis of ssu4dc and ssu4d showed that ssu4d contained an intron between +355 nt to +1125 nt downstream of transcriptional iniative site. ssu4dc contained 54 bp of 5' untranslated region (UTR), and an open reading frame of 174 amino acids consisting of a chloroplast transit peptide with 57 amino acids and a mature protein of 117 amino acids. The deduced amino acid sequence of ssu4dc shared 95-96% identity with L. gibba RbcS protein. Real time-PCR analysis showed differential expression of individual rbcS genes in light-grown Lemna gibba. And the levels of SSU4dc mRNA was regulated by the action of phytochrome, there was variability in the amount of expression of SSU4dc RNA comprared to the SSU1 and SSU5B from Lemna gibba.