The Research On Functions Of Genes All5292 And Alr0647 From Anabaena (Nostoc) PCC7120

Recently, a group of four genes (cpcS, cpcT, cpcU, and cpcV) has been identified in Synechococcus sp. PCC7002 that code for lyases that attach PCB to cysteine-84 (consensus numbering) of theβ-subunits of CPC and possibly allophycocyanin, homologous genes are also found in other cyanobacteria[1]. Genes all5292 and alr0647 in the cyanobacterium, Anabaena (Nostoc) PCC7120, are homologous to the biliprotein lyase cpcS and cpcT. The functions of the encoded proteins were tested in vitro, and in a heterologous E. coli system with plasmids conferring biosynthesis of the phycocyanobilin (PCB) chromophore and of the acceptor proteins,β-phycoerythrocyanin (PecB) orβ-phycocyanin(CpcB). The reconstituted products were determined with absorption spectra and fluorescence spectra. The resuLts showed that no lyase activity was found for the lyase homologues, All5292 and Alr0647.Subsequently, synthesis of the desired proteins was checked by SDS-PAGE and Western blot. The resuLts showed that all genes, including all5292 and alr0647, were successfuL expressed in every heterologous E. coli system. And in this process, we also found that All5292 is soluble but the other is insoluble in a heterologous E. coli system.In this work, the expression of genes all5292 and alr0647 from Anabaena sp. PCC 7120 was studied by reverse transcription PCR. RT-PCR analysis showed that all5292 and alr0647 are transcribed when the cells were subjected to a shift from a nitrogen repletion condition to a nitrogen depletion condition. But these observations require more detailed investigations because it is conceivable that both homologues are present during transients, or under other physiological conditions.