<p>If, like other organelles, UCYN-A relies on proteins imported from the host for normal functioning, characterizing the import system and the targeting sequence is essential before transplanting the organelle into a new host organism. Building upon the work of Coale et al. [1], we aimed to advance the understanding of uTP by identifying its precise sequence.</p>
<p>Starting from the raw proteomics data from [1], we selected 368 proteins expressed by the host and significantly enriched in UCYN-A and performed multiple sequence alignment (MSA). Using the alignment we identified a strongly conserved C-terminal region in many of the imported proteins similar to that reported by [1]. We selected a subset of 206 proteins with highly similar (>60% sequence identity) C-terminal alignments, indicating that these are likely to contain uTP, </p>
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<imgsrc="https://static.igem.wiki/teams/5054/msa.png"alt="Fig 1: Graphical overview of the experiment plan.">
<figcaption>Fig 2: Multiple sequence alignment (MSA) of all UCYN-A enriched sequences. The strongly aligned C-terminal region is highlighted (positions 880-1010 in the alignment)
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<p>Motif analysis confirmed findings similar to [1], revealing 8 conserved motifs in the C-terminal region (Fig 2). Further investigation of motif co-occurrence and relative positioning uncovered common patterns: two motifs consistently appeared near the start of the C-terminal region at fixed positions, followed by various combinations of the remaining motifs. This arrangement is reminiscent of a potential sub-organellar localization mechanism, where the initial two motifs could target UCYN-A, while subsequent motifs may specify localization within the endosymbiont, as is the case with chloroplast targeting, where a bipartite N-terminal targeting sequence specifies stromal and thylakoidal localization. More research is needed however to investigate this hypothesis.</p>
