Investigating the Mucin Utilization Capabilities of Akkermansia muciniphila

Akkermansia muciniphila is a commensal gut microbe that has been implicated in a multitude of human health conditions. A. muciniphila lives deeply embedded within the mucin layer, where it survives by consuming mucin as a source of carbon and nitrogen. This microbe has been shown to influence host cellular activity as well as protect against gut inflammation, obesity, and metabolic disorders such as diabetes. First isolated in an effort to discover mucin-degrading bacteria, this microbe has also been thought of as a potential probiotic. However, despite nearly two decades of study, the biological mechanisms by which it metabolizes mucin are unknown. Specialized metabolic machinery is required to degrade mammalian gastrointestinal mucin due to its complex structure. Recently, our lab has discovered several unique aspects of mucin metabolism that this proposal seeks to study further. Firstly, we have shown that A. muciniphila can accumulate mucin intracellularly, and this process is specific to mucin. Furthermore, we have pioneered a means to perform transposon (Tn) mutagenesis in A. muciniphila as well as subsequent high-throughput INSeq studies to assay the genetic determinants mucin utilization. These have shown that mucin metabolism occurs in several discrete steps: the binding to mucin extracellularly; its import into the cell through dedicated mucin transporters; and its subsequent degradation and metabolism intracellularly. I propose to identify genes required for mucin accumulation, as well as expand the knowledge of the glycoside hydrolases and mucin-binding proteins produced by A. muciniphila. While studies seem to suggest that this microbe has numerous health benefits, the knowledge of how A. muciniphila interacts with human host cells is predicated upon a deeper understanding of the fundamental biology and the mechanisms that enable it to thrive within the gastrointestinal mucin layer.