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WSD-1 Chalcopyrite-binding peptide

WSD-1 Chalcopyrite-binding peptide

Background and rational

Caulobacter crescentus is a bacterium frequently inhabiting fresh water lakes and streams. An important model for understanding microbial physiology, Caulobacter is known for it’s differentiated cell cycle. In particular, cells switch between two states; a motile “swarmer” cell and a static “stalked” cell. Here, the Caulobacter lifestyle provides a chasis for engineering solutions that require mobility interspersed with surface binding. Another potentially useful Caulobacter trait a regularly arrayed protein surface layer known as the S-layer. The S-layer is most frequently associated with protection, as the bacterium remains covered at all times throughout it’s lifestyle. Indeed, a platform protein expression system has been engineered to exploit the S-layer for simple, scalable protein display. In recent years, there have been several examples where target proteins (such as immunoglobulins) are displayed to bind pathogen associated molecular protein (PAMPS).

The Caulobacter traits above could be useful for applications in biomining, where a bacterium can be imagined to bind and recover select minerals from a complex mixture. Recently, several peptides were discovered that selectively bind to economically important minerals in ore slurries. We therefore hypothesized that these peptides could be integrated into the Caulobacter S-layer as a proof of concept for biomining applications.

Experimental overview

As a preliminary test, we observed increased Chalcopyrite precipitation with Caulobacter cells expressing a Chalcopyrite binding peptide in the S-layer. While non-quantitative, the data showed noticeable differences in precipitate settle when the peptide expressed in various locations in the S-layer. See the video below.

Sequence and Features