Expanding the DOPA Universe with Genetically Encoded, Mussel‐Inspired Bioadhesives for Material Sciences and Medicine

Abstract

Catechols are a biologically relevant group of aromatic diols that have attracted much attention as mediators of adhesion of “bio‐glue” proteins in mussels of the genus Mytilus. These organisms use catechols in the form of the noncanonical amino acid l‐3,4‐dihydroxyphenylalanine (DOPA) as a building block for adhesion proteins. The DOPA is generated post‐translationally from tyrosine. Herein, we review the properties, natural occurrence, and reactivity of catechols in the design of bioinspired materials. We also provide a basic description of the mussel's attachment apparatus, the interplay between its different molecules that play a crucial role in adhesion, and the role of post‐translational modifications (PTMs) of these proteins. Our focus is on the microbial production of mussel foot proteins with the aid of orthogonal translation systems (OTSs) and the use of genetic code engineering to solve some fundamental problems in the bioproduction of these bioadhesives and to expand their chemical space. The major limitation of bacterial expression systems is their intrinsic inability to introduce PTMs. OTSs have the potential to overcome these challenges by replacing canonical amino acids with noncanonical ones. In this way, PTM steps are circumvented while the genetically programmed precision of protein sequences is preserved. In addition, OTSs should enable spatiotemporal control over the complex adhesion process, because the catechol function can be masked by suitable chemical protection. Such caged residues can then be noninvasively unmasked by, for example, UV irradiation or thermal treatment. All of these features make OTSs based on genetic code engineering in reprogrammed microbial strains new and promising tools in bioinspired materials science.

Photoadhesive Materials Containing 2-Mercaptopyridyl Moieties

“…Each mixture was dropped on a substrate (glass, Cu, treated Cu, or Al), sandwiched with another glass substrate. The adhesive area was 30 mm 2 . UV irradiation at a wavelength of 365 nm (50 mW cm -2 , 6.0 J cm -2 ) was performed toward over the glass substrate.…”

“…As an attractive chemical structure that enables to adhere dissimilar materials, catechol and its analogues are studied vigorously [2,3]. Wilker et al…”

Strategic Advances in Spatiotemporal Control of Bioinspired Phenolic Chemistries in Materials Science

“…Furthermore, catechols interact with boron acids and silyl species in a reversible way (despite some degree of covalent bonding), [79][80][81] which could be readily leveraged for synthesizing various advanced dynamic materials (see details in Section 3.2). Another attractive merit of catechols is their redox activity, which is sufficient to reduce some noble metal ions such as Ag + , Pt 3+ , Pd 2+ , and Au 3+ .…”

“…Photoremovable protecting groups (PPGs) hold promise in eliciting spatiotemporal control over catechol chemistry. [81,157] Nitrobenzyl compounds, one of the most established PPGs, have recently been explored for producing biomimetic catecholcontaining glues with light-controlled wet adhesion power in vivo ( Figure 6B). [158] Specially, nitrobenzyl was applied to temporarily mask the catechol functionality, which can be recovered in response to precise light triggers.…”

Combating Antimicrobial Resistance With New-To-Nature Lanthipeptides Created by Genetic Code Expansion

“…This Mm- or Methanosarcina barkeri PylRS ( Mb PylRS) variants should be an ideal starting enzyme for the evolution of enzyme mutants with high specificity for smaller substrates. These and other advances in the field are recently summarized in a series of specific reviews ( Arranz-Gibert et al, 2019 ; Budisa and Schneider, 2019 ) and highlights ( Mayer, 2019 ; Yanagisawa et al, 2019 ).…”