Sequence determinants of protein aggregation: tools to increase protein solubility

Abstract

Escherichia coli is one of the most widely used hosts for the production of recombinant proteins. However, very often the target protein accumulates into insoluble aggregates in a misfolded and biologically inactive form. Bacterial inclusion bodies are major bottlenecks in protein production and are hampering the development of top priority research areas such structural genomics. Inclusion body formation was formerly considered to occur via non-specific association of hydrophobic surfaces in folding intermediates. Increasing evidence, however, indicates that protein aggregation in bacteria resembles to the well-studied process of amyloid fibril formation. Both processes appear to rely on the formation of specific, sequence-dependent, intermolecular interactions driving the formation of structured protein aggregates. This similarity in the mechanisms of aggregation will probably allow applying anti-aggregational strategies already tested in the amyloid context to the less explored area of protein aggregation inside bacteria. Specifically, new sequence-based approaches appear as promising tools to tune protein aggregation in biotechnological processes.

The N-terminal Helix Controls the Transition between the Soluble and Amyloid States of an FF Domain

“…It is now accepted that specific and continuous sequence segments of a protein promote amyloid fibril formation and participate to the establishment of the β-core of the mature fibrils [34], [35]. Different computational methods have been developed to predict those sequential stretches [36], [37].…”

Sequence dependent aggregation of peptides and fibril formation

“…It has been shown that poly-aminoacids can also form amyloid under appropriate condition 5 . However, the propensity of a given polypeptide to form amyloid fibrils as well as the condition under which they form depends very significantly on its amino acid sequence showing that the problem is much more complex than it could be initially thought of but also giving hope for curing amyloid diseases 6 . X-ray fiber diffraction data indicate that amyloid fibrils are commonly characterized by the cross-β-sheets a) Electronic mail: hoang@iop.vast.vn with strands running perpendicularly to the fibril's longitudinal axis 7 .…”

Increase in the Solubility of Recombinant Mink Growth Hormone at Low Cultivation Temperature ofE. Coli

“…now a new approach based on several earlier or recent observations has appeared. the aggregation of proteins expressed in E. coli is supposed to be a sequence selective process driven by certain "hot spots" within the protein sequence (13,14). the propensity of mGh for interaction could also be specifi c sequence-dependent.…”