H-protein of the glycine cleavage system in Flaveria: alternative splicing of the pre-mRNA occurs exclusively in advanced C4 species of the genus

✍ Scribed by Stanislav Kopriva; Chen-cai Chu; Hermann Bauwe

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 697 KB
• Volume: 10
• Category: Article
• ISSN: 0960-7412
• DOI: 10.1046/j.1365-313x.1996.10020369.x

✦ Synopsis

A recent paper reports on the occurrence of alternative splicing of H‐protein pre‐mRNA in the C~4~ species, Flaveria trinervia, that is organ‐specifically regulated. The analysis of 11 other species of the genus, Fcronquistii and F. pringlei (C~3~), F. anomala, F. chloraefolia, F. floridana, F. linearis and F. pubescens (C~3~–C~4~ intermediate), F. brownii (C~4~‐like), F. palmeri, F. bidentis and F. australasica (C~4~), revealed that this post‐transcriptional effect is not specific for F. trinervia. It occurs in all the examined C~4~ species of the genus Flaveria except the less advanced C~4~‐like species, F. brownii. Both the position and the direct effect of alternative splicing, the addition of two alanine residues near to the N‐terminus of the derived mature H‐protein, are invariant. A quantification of the relative amounts of both transcripts revealed that, as in F.trinervia, the alternative mRNA strongly dominates in leaves. In sharp contrast, none of the C~3~,C~3~–C~4~ intermediate, or C~4~‐like species showed alternative splicing. By Western analysis both H‐isoproteins have been detected in F. trinervia and their ratio approximately corresponds to the measured transcript levels. It is concluded that alternative splicing leads to the synthesis of two different H‐proteins of the glycine cleavage system in all advanced Flaveria C~4~ species.