Harnessing sortase A transpeptidation for advanced targeted therapeutics and vaccine engineering

Sortases: structure, mechanism, and implications for protein engineering

Sortase enzymes are critical cysteine transpeptidases on the surface of bacteria that attach proteins to the cell wall and are involved in the construction of bacterial pili. Due to their ability to recognize specific substrates and covalently ligate a range of reaction partners, sortases are widely used in protein engineering applications via sortase-mediated ligation (SML) strategies. In this review, we discuss recent structural studies elucidating key aspects of sortase specificity and the catalytic mechanism. We also highlight select recent applications of SML, including examples where fundamental studies of sortase structure and function have informed the continued development of these enzymes as tools for protein engineering.

Toward Clinical Applications: Transforming Nonantibiotic Antibacterials into Effective Next-Generation Supramolecular Therapeutics

Antibiotic resistance is a major driver of morbidity and mortality worldwide, necessitating alternatives. Due to their mechanism of action, bacteriophages, endolysins, and antimicrobial peptides (coined herein as nonantibiotic antibacterials, NAA) have risen to tackle this problem and led to paradigms in treating antibiotic-resistant bacterial infections. However, their clinical applications remain challenging and have been seriously hampered by cytotoxicity, instability, weak bioactivity, low on-target bioavailability, high pro-inflammatory responses, shorter half-life, and circulatory properties. Hence, to transit preclinical phases and beyond, it has become imperative to radically engineer these alternatives into innovative and revolutionary therapeutics to overcome recalcitrant infections. This perspective highlights the promise of these agents, their limitations, promising designs, nanotechnology, and delivery approaches that can be harnessed to transform these agents. Finally, I provide an outlook on the remaining challenges that need to be tackled for their widespread clinical administration.

Steric-Deficient Oligoglycine Surrogates Facilitate Multivalent and Bifunctional Nanobody Synthesis via Combined Sortase A Transpeptidation and Click Chemistry

Conferring multifunctional properties to proteins via enzymatic approaches has greatly facilitated recent progress in protein nanotechnology. In this regard, sortase (Srt) A transpeptidation has facilitated many of these developments due to its exceptional specificity, mild reaction conditions, and complementation with other bioorthogonal techniques, such as click chemistry. In most of these developments, Srt A is used to seamlessly tether oligoglycine-containing molecules to a protein of interest that is equipped with the enzyme's recognition sequence, LPXTG. However, the dependence on oligoglycine attacking nucleophiles and the associated cost of certain derivatives (e.g., cyclooctyne) limit the utility of this approach to lab-scale applications only. Thus, the quest to identify appropriate alternatives and understand their effectiveness remains an important area of research. This study identifies that steric and nucleophilicity-associated effects influence Srt A transpeptidation when two oligoglycine surrogates were examined. The approach was further used in complementation with click chemistry to synthesize bivalent and bifunctional nanobody conjugates for application in epithelial growth factor receptor targeting. The overall technique and tools developed here may facilitate the advancement of future nanotechnologies.

Molecular engineering tools for the development of vaccines against infectious diseases: current status and future directions

INTRODUCTION

The escalating global changes have fostered conditions for the expansion and transmission of diverse biological factors, leading to the rise of emerging and reemerging infectious diseases. Complex viral infections, such as COVID-19, influenza, HIV, and Ebola, continue to surface, necessitating the development of effective vaccine technologies.

AREAS COVERED

This review article highlights recent advancements in molecular biology, virology, and genomics that have propelled the design and development of innovative molecular tools. These tools have promoted new vaccine research platforms and directly improved vaccine efficacy. The review summarizes the cutting-edge molecular engineering tools used in creating novel vaccines and explores the rapidly expanding molecular tools landscape and potential directions for future vaccine development.

EXPERT OPINION

The strategic application of advanced molecular engineering tools can address conventional vaccine limitations, enhance the overall efficacy of vaccine products, promote diversification in vaccine platforms, and form the foundation for future vaccine development. Prioritizing safety considerations of these novel molecular tools during vaccine development is crucial.