Functional identification and expression analysis of sucrose biosynthesis related genes from Synechococcus marinus sp. PCC 7002

CUMINO A; TORRES, L; GIARROCCO L; COVACEVICH F; SALERNO G

Gdansk, Polonia

Workshop; 6th European Workshop on the Molecular Biology of Cyanobacteria; 2005

The University of Gdañsk,Universiteit van Amsterdam

The present study describes:  a) the molecular cloning of the genes encoding SPS and SPP of Synechococcus sp. PCC 7002, and the functional identification by heterologous expression and biochemical analysis of the recombinant enzymes, and b) the concomitant expression of spsA and sppA in relation to the cell growth phase and to salt concentration. Syc-spsA and Syc-sppA encode a 81-kDa and a 33-kDa polypeptide, respectively, which are ca. 61% and 23 % identical to SPS and SPP of Synechocystis sp. PCC 6803, respectively.  Syc-SPS is a bidomainal SPS-type, composed by a Glucosyl-Transferase Domain (GTD) and a Phospho-Hydrolase Domain (PHD). Syc-spsA and Syc-sppA expression at transcript levels were markedly increased in cells at stationary phase and in high osmolarity conditions. Sequence analysis of the Syc genome revealed that a duplication event of a bidomainal SPS-like might be originated to extant SPP. A gene fusion of a GTD and a PHD-like primordial domain was proposed to have produced a two-domain common ancestral SPS-like gene.