# Population-level heterogeneity complicates utilization of Synechococcus elongatus PCC 7942 surface display platforms

## TL;DR

Researchers improved surface display systems in a cyanobacterium but found cell-to-cell differences limited their effectiveness.

## Contribution

Modified cyanobacterial surface proteins to enable interaction with other targets, revealing challenges due to cellular heterogeneity.

## Key findings

- Re-engineered SomA successfully translocated to the cell surface and bound to compatible ligands.
- Heterogeneity in tag accessibility among cells limited the effectiveness of surface display systems.
- Best-performing designs showed low attachment penetrance despite functional translocation.

## Abstract

Surface display technologies have been primarily developed for heterotrophic microbes, leaving photosynthetic counterparts like cyanobacteria with limited molecular tools. Here, we expanded upon surface display systems in
Synechococcus elongatus
PCC 7942 by modifying two outer-membrane proteins, SomA and Intimin, to display tags (
e.g.
, SpyTag) to mediate physical interactions of living cyanobacteria with other biotic and abiotic targets. While re-engineered SomA constructs successfully translocated to the cell surface and could bind to compatible ligands, the efficacy of the best-performing designs was limited by a poorly-understood heterogeneity in the accessibility of the tags in living cells, resulting in low attachment penetrance.