Directionality in the E. coli periplasm: molecular choreography or chaos?

Our understanding of prokaryote biology has progressed leaps and bounds in recent decades, but details of how they coordinate functions within the cell envelope that surrounds them remain rudimentary. Gram-negative bacteria are protected by a cell envelope that is composed of two membranes separated by the aqueous periplasm. The latter is a densely packed, oxidising, environment in which is housed the peptidoglycan cell wall and approximately 300 different proteins. Crucially and rather perplexingly, the periplasm does not contain any sources of energy - there is no ATP present and there does not appear to be an overall H+ gradient across the compartment - certainly none has been detected. Therefore it is unknown how directionality for various processes including (a) delivery of lipoproteins and unfolded outer membrane proteins to the outer membrane and (b) delivery of phospholipids away from the outer membrane is achieved. Is it simply a case of so many random interactions in a dense environment that enough of these are productive or is it a case of carefully choreographed interactions - or a combination of these two extremes? I will use a combination of molecular modelling, simulations and machine learning informed by experimental data to investigate these questions.