Mussel foot proteins support higher-yield synthetic spider silk
A team of researchers led by Fuzhong Zhang, a professor of energy, environmental and chemical engineering at the McKelvey School of Engineering at the University of Washington in St Louis, has found a way to use sticky mussel foot protein fragments to generate higher-yield synthetic spider silk proteins.
“The outstanding mechanical properties of natural spider silk come from its very large and repetitive protein sequence,” Dr Zhang explained. “However, it is extremely challenging to ask fast-growing bacteria to produce a lot of repetitive proteins.
“To solve this problem, we went looking for disordered proteins that can be genetically fused to silk fragments to promote molecular interaction, so that strong fibres can be made without using large repetitive proteins."
Building on his earlier work with mussel foot proteins, which are intrinsically disordered, Dr Zhang discovered that their fragments could be placed at the ends of protein sequences to create new spider silk fusion proteins, known as bi-terminal Mfp fused silks or btMSilks.
These are said to have eightfold higher yields than recombinant silk proteins, resulting in 8 grams of fibre material per 1 litre of bacterial culture, enough to begin fabric tests.
Less repetitive, yet lightweight, the material is still at least double the strength of recombinant spider silk.
Next up on the agenda is exploring how the fibres could be fine-tuned to suit demand.
“Because our synthetic silk is made from cheap feedstock using engineered bacteria, it presents a renewable and biodegradable replacement for petroleum-derived fibre materials like nylon and polyester,” the professor said.
Read about the researchers’ findings in full in the journal Nature Communications here.
