Bacterial communities within the human body greatly influence human health and play a significant role in disease predisposition, pathogenic, physical fitness, and dietary responsiveness. Importantly, bacteria utilize highly cooperative macromolecular machines to accomplish many cellular functions. Here we seek to understand, with molecular and atomistic fidelity, two such machines: the cellulosome and the chemosensory array, which underlie the phenomena of bacterial plant fiber degradation and chemotaxis respectively.
Biofuels:
Bacteria can make a living off a very wide range of food sources. This agnosticism enables them to, among other things, serve as essential symbionts in animal digestive tracts where they assist their hosts in degrading cellulose fibers into metabolizable compounds. In particular, bacteria in the rumen of the cow face an especially tough job (see
Tight Job in the Gut
), digesting the hardy cellulose fibers of grasses. Key to their task are molecular tentacles on the cell surface of certain gut bacteria, so-called cellulosomes (pictured right), which develop a tight grasp on cellulose and then effectively cleave the molecules. In general, human gut bacteria (and their role in the broader human microbiome) are one of the most intensely researched topics in medicine.
Bacterial Chemotaxis:
Bacteria monitor their environments and respond by way of a fundamental sensory capability known as chemotaxis---one of the best studied behavioral systems in biology. Chemotactic responses in bacteria involve large complexes of sensory proteins, known as chemosensory arrays, that process the information obtained from the bacteria's habitat to determine its swimming pattern. In this sense, the chemosensory array functions as a bacterial brain, transforming sensory input into motile output. Despite great strides in the understanding of how the chemosensory array's constituent proteins fit and work together, a high-resolution description has, until recently, remained elusive (see
Computing the Bacterial Brain
). Here we are combining computational and experimental techniques to explore in detail the molecular mechanisms underlying sensory signal transduction and amplification within this amazing biological apparatus.