<p>To understand the functioning of the UCYN-A import mechanism, we attempted to <strong>identify the proteins involved in translocating</strong> host-encoded proteins into UCYN-A. First, we located genes in the host genome that are potentially involved in the translocation, based on their similarity to proteins in other import mechanisms such as from <em>Paulinella chromatophora</em> (UCYN-A analogue for photosynthesis). Potential chaperones analogous to heat-shock proteins were also included in the search. These chaperones are hypothesized to bind to proteins tagged by the uTP and keep them from folding, allowing translocation through the UCYN-A membrane. We then followed this by <strong>obtaining the tertiary structure of all candidate proteins</strong> using a structure prediction tool, and used <strong>docking</strong> tools to select candidate proteins likely to bind the previously identified transit motifs.</p>
<p>In addition to <em>in silico</em> experiments, we also aimed to investigate the transport mechanisms of UCYN-A <em>in vivo</em>. Instead of making use of plants as target organisms, we opted for using single-cell model eukaryote organisms, namely the yeast <em>S. cerevisiae</em> and the green alga <em>C. reinhardtii</em>. The initial <em>in vivo</em> characterization of the UCYN-A transport system involved <strong>examining the expression and localization of the UCYN-A transit peptides in these eukaryotic model organisms</strong> to test whether uTP would have any unexpected effect on cell viability and would not target any other organelle. To this end, we designed vectors, cloned them using Gibson-assembly, transformed bacteria, purified expression plasmids, and transformed those into <em>S. cerevisiae</em> and <em>C. reinhardtii</em>. We expressed uTP-tagged fluorescent proteins, together with controls targeting other organelles, and localization was assessed using fluorescence microscopy. Our preliminary results indicate that uTP did not target any other organelle and did not lead to alterations in cell morphology.</p>
<p>Studies have demonstrated the insertion of bacteria into cells by engineering endosymbionts in <em>S. cerevisiae</em> using either <em>E. coli</em> or <em>S. elongatus</em><ahref="https://link.springer.com/article/10.1007/s00438-018-1448-1">[Mehta2018 EngineeringMitochondria]</a>. Another study successfully inserted <em>Azotobacter</em> strains into <em>C. reinhardtii</em><ahref="https://www.jstor.org/stable/24358669">[Nghia1986 UptakeReinhardii]</a>. Building on this research, we initially aimed to <strong>develop a reliable protocol for transplanting a nitroplast</strong> into <em>C. reinhardtii</em> and <em>S. cerevisiae</em> as a <strong>proof-of-concept</strong> for transplantation into other eukaryotes, using polyethylene glycol (PEG) fusion protocols. However, due to time limitations, we started out with the model eukaryotic bacteria, <em>E. coli</em>, and refined a protocol for its fusion with <em>S. cerevisiae</em>.</p>
<p>Studies have demonstrated the insertion of bacteria into cells by engineering endosymbionts in <em>S. cerevisiae</em> using either <em>E. coli</em> or <em>S. elongatus</em><ahref="https://link.springer.com/article/10.1007/s00438-018-1448-1"style="color: #C6EBE8;">[Mehta2018 EngineeringMitochondria]</a>. Another study successfully inserted <em>Azotobacter</em> strains into <em>C. reinhardtii</em><ahref="https://www.jstor.org/stable/24358669"style="color: #C6EBE8;">[Nghia1986 UptakeReinhardii]</a>. Building on this research, we initially aimed to <strong>develop a reliable protocol for transplanting a nitroplast</strong> into <em>C. reinhardtii</em> and <em>S. cerevisiae</em> as a <strong>proof-of-concept</strong> for transplantation into other eukaryotes, using polyethylene glycol (PEG) fusion protocols. However, due to time limitations, we started out with the model eukaryotic bacteria, <em>E. coli</em>, and refined a protocol for its fusion with <em>S. cerevisiae</em>.</p>
<p>We obtained <em>B. bigelowii</em> as a gift from Dr. Kyoko Hagino (Kochi University, Japan) and cultured it according to the protocol. For the transplantation of the nitroplast into a different model organism, we were also required to isolate this organelle from its host. Our project also implemented the protocol for nitroplast isolation from its host, according to the protocol and suggestions provided by Dr. Tyler Coale (University of California, San Diego, USA). Isolated UCYN-A could potentially be used for PEG fusion with other eukaryotes.</p>
<p>Finally, we have also wondered how our project would affect society. For this, our human practices team has actively worked to understand the possible consequences of our project. Also, wider acceptance of our idea goes hand in hand with educating the general population. Last but not least, we have also assessed the potential economic benefits of our idea and the omission of fertilizer use in agriculture. For this, we made an <strong>economic analysis</strong> and business plan.</p>
