Bacterial post-translational changes: the possible enigma of multidrug resistance.

Conventionally, bacteria were perceived as simple life forms. Nevertheless, they hold extraordinary capabilities to adapt and persist in challenging environments through various survival mechanisms, notably post-translational modifications (PTMs). Amongst these, glycosylation stands out as a vital process that modulates bacterial physiology, enhances stress tolerance, and supports growth in nutrient-deficient or hostile conditions. It involves the enzymatic attachment of sugar chains to proteins, playing a crucial role in maintaining protein integrity, structure, and function, thereby promoting bacterial resilience. Two decades ago, the bacterial-glycosylation was relatively less documented process due to the perception that it lacks glycosylation machinery. However, in recent times the process has been increasingly acknowledged as a key factor in developing bacterial virulence and resistance against antibiotics. The advanced proteomic technologies have revealed various glycan-patterns in numerous bacterial species, linking them to immune escape mechanisms, biofilm development, and environmental adaptation. Significantly, glycosylation of surface proteins assists bacteria in evading host immune responses and contributes to multidrug resistance (MDR) by modifying drug targets or limiting drug entry. This review for the first time attempts to document bacterial glycosylation comprehensively, and its significant role in developing antibiotic resistance and survival.