Complementation of a phycocyanin-bilin lyase from Synechocystis sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte Guillardia theta

<p>Abstract</p> <p>Background</p> <p>Cryptophytes are highly compartmentalized organisms, expressing a secondary minimized eukaryotic genome in the nucleomorph and its surrounding remnant cytoplasm, in addition to the cell nucleus, the mitochondrion and the plastid. Because the members of the nucleomorph-encoded proteome may contribute to essential cellular pathways, elucidating nucleomorph-encoded functions is of utmost interest. Unfortunately, cryptophytes are inaccessible for genetic transformations thus far. Therefore the functions of nucleomorph-encoded proteins must be elucidated indirectly by application of methods in genetically accessible organisms.</p> <p>Results</p> <p>Orf222, one of the uncharacterized nucleomorph-specific open reading frames of the cryptophyte <it>Guillardia theta</it>, shows homology to <it>slr</it>1649 of <it>Synechocystis </it>sp. PCC 6803. Recently a further homolog from <it>Synechococcus </it>sp. PCC 7002 was characterized to encode a phycocyanin-β155-bilin lyase. Here we show by insertion mutagenesis that the <it>Synechocystis </it>sp. PCC 6803 <it>slr</it>1649-encoded protein also acts as a bilin lyase, and additionally contributes to linker attachment and/or stability of phycobilisomes. Finally, our results indicate that the phycocyanin-β155-bilin lyase of <it>Synechocystis </it>sp. PCC 6803 can be complemented <it>in vivo </it>by the nucleomorph-encoded open reading frame <it>orf</it>222.</p> <p>Conclusion</p> <p>Our data show that the loss of phycocyanin-lyase function causes pleiotropic effects in <it>Synechocystis </it>sp. PCC 6803 and indicate that after separating from a common ancestor protein, the phycoerythrin lyase from <it>Guillardia theta </it>has retained its capacity to couple a bilin group to other phycobiliproteins. This is a further, unexpected example of the universality of phycobiliprotein lyases.</p

Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte -2

Ith the cryptophytic 222. The upper figure displays the wild type situation. The lower figure shows the insertion site of 222, without its putative transit peptide and the gene into 1649 by simultaneously affecting the reading frame of 1649 and its -acting upstream signals. (B) Immunoblot with Slr1649 (upper) and Slr1470 (lower) specific antibodies. Cells from Δ, wild type and complemented strains were disrupted and the protein extracts were separated by SDS-PAGE. Neither in the fraction of Δcells nor in the fraction of the complemented strain were signals of the Slr1649 antibody detectable. Specific polyclonal Slr1470 antibodies were used as a loading control and clear signasl at the expected size were obtained in all three protein fractions.<p><b>Copyright information:</b></p><p>Taken from "Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte "</p><p>http://www.biomedcentral.com/1471-2229/8/56</p><p>BMC Plant Biology 2008;8():56-56.</p><p>Published online 16 May 2008</p><p>PMCID:PMC2408579.</p><p></p

Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte -0

D from the analysis, leaving 116 amino acid sites for log determinant (LogDet) distance estimates with removal of invariant sites using the program LDDist. From this a Neighbor – net splits graph was constructed, which is visualized with Splitstree4. Highlighted are four monophyletic groups: Two of them resemble CpeT-like (phycoerythrin operon protein) proteins (highlighted in green) and two groups harbor members of the Slr1649-like type (highlighted in red). Not shown: The sequences of PCC 7942 Synpcc7942_0800 and PCC 6301 Syc0738_d are identical as well as the sequences of PCC 7942 Synpcc7942_0772 and PCC 6301 Syc0764_d and the sequences of SS120 Pro0342 and CCMP1375 orf195.<p><b>Copyright information:</b></p><p>Taken from "Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte "</p><p>http://www.biomedcentral.com/1471-2229/8/56</p><p>BMC Plant Biology 2008;8():56-56.</p><p>Published online 16 May 2008</p><p>PMCID:PMC2408579.</p><p></p

Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte -5

D from the analysis, leaving 116 amino acid sites for log determinant (LogDet) distance estimates with removal of invariant sites using the program LDDist. From this a Neighbor – net splits graph was constructed, which is visualized with Splitstree4. Highlighted are four monophyletic groups: Two of them resemble CpeT-like (phycoerythrin operon protein) proteins (highlighted in green) and two groups harbor members of the Slr1649-like type (highlighted in red). Not shown: The sequences of PCC 7942 Synpcc7942_0800 and PCC 6301 Syc0738_d are identical as well as the sequences of PCC 7942 Synpcc7942_0772 and PCC 6301 Syc0764_d and the sequences of SS120 Pro0342 and CCMP1375 orf195.<p><b>Copyright information:</b></p><p>Taken from "Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte "</p><p>http://www.biomedcentral.com/1471-2229/8/56</p><p>BMC Plant Biology 2008;8():56-56.</p><p>Published online 16 May 2008</p><p>PMCID:PMC2408579.</p><p></p

Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte -3

Ar blue bands in the gradient. The upper layer contained chlorophylls. The phycobilisomes of Δcells had a diminished migration compared to the wild type ones, whereas the phycobilisomes from the complemented strain (Comp) had a migration equivalent to the wild type.<p><b>Copyright information:</b></p><p>Taken from "Complementation of a phycocyanin-bilin lyase from sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte "</p><p>http://www.biomedcentral.com/1471-2229/8/56</p><p>BMC Plant Biology 2008;8():56-56.</p><p>Published online 16 May 2008</p><p>PMCID:PMC2408579.</p><p></p