The Matrix Proteome: Protein Actors in the Extracellular Bacterial Biofilm

Despite their abundance, extracellular matrix proteins remain understudied, presenting a blind spot in biofilm research. In this chapter, we examine the matrix proteins and their biofilm-associated roles through a cinematic lens. We begin by exploring the wide-angle view of these microbial films, examining whole biofilm proteomics and its impact on our understanding of biofilm composition and physiology. The following scenes take us into a deeper view of biofilm matrix proteomics, discussing the two largest subcategories, proteins associated with the cell surface and proteins bound to matrix polymers. Through biofilm matrix proteomics, we gain insights into the overall extracellular protein landscape and their unique identities and functions, setting the stage for a deeper exploration of individual matrix proteins. Focusing on the model biofilm organism Pseudomonas aeruginosa, we discuss matrix protein dynamics, revealing a stark contrast between the plethora of putative proteins identified and the limited understanding of their discrete biofilm-associated functions. Finally, we delve into close-up descriptions of the nine individually studied P. aeruginosa matrix-associated proteins and their functions in the biofilm. Through this cinematic exploration, we shed light on the complexities of the biofilm matrix proteome and call for continued discovery in this expanding field.