Directed evolution of multivalent glycoclusters

Complex glyconjugates are usually rationally designed due to convenience and a lack of understanding of glycan structure-function. Krauss et al. describe, for the first time, a method for evolving glycans with novel binding properties. Basically, the authors make use of DNA which acts as a scaffold for presenting various glycans in multiple positions. Glycans are installed via 'click' chemistry, and accordingly the position of alkyne-modified nucleotides in the DNA sequence determines the position of these glycans. These unnatural nucleotides are easily randomly introduced into a template scaffold DNA by PCR. Thus, once a particular glycan has been identified through a binding selection, the DNA can be amplified and sequenced, revealing the identity of the multivalent glycan. This is very clever stuff, and I look forward to seeing more progress in the future!

The Bacterial Nanorecorder: Engineering E. coli to Function as a Chemical Recording Device.

Synthetic genetic circuits are of great interest in synthetic biology research. These circuits have been employed for a variety of functions from memory devices to sensing cancer cells towards their death or disablement. Using the tools of synthetic biology Bhomkar et al. were able to create a novel E. coli strain that can be used as a highly specific, simple and inexpensive chemical recording device. This device allows for the determination of when and what chemical the strain has been exposed to. Upon exposure to a signal molecule, it generates a quantifiable phenotypic response allowing for estimation of the time of the signal exposure.

Creation of New Metabolic Pathways or Improvement of Existing Metabolic Enzymes by In Vivo Evolution in Escherichia coli

This paper sequentially details how to design and construct a recombinant E. coli to create new metabolic pathways of new enzymes using in vivo evolution. It is based on the principles of in vivo directed evolution and rational design of a microorganism. This is achieved by placing an organism in a novel environment. Only a few mutations were observed under the metabolic pressure and the main mutations were found to occur in the coding or promoter region.