Dynamic microbial molecular activities

点击翻译按钮获取中文摘要

Microbes exist in almost every ecosystem on Earth. The components of microbiota play important functional roles in their environments. The relative composition of components of the microbiota, both of organisms and of molecules within those organisms, can be dynamic; they can change depending on factors such as nutritional sources, infection and others. The goal of this program is to investigate some of those components that are expected from their functions to be dynamic. ***1. Bacterial glycoside hydrolases***A main focus of the previous grant period has been on bacterial enzymes that respond to changing sources of nutrition. We have been concentrating on glycoside hydrolases from Bacteroides thetaiotaomicron (Bt). We are interested in understanding the reason that Bt has evolved such a large repertoire of GHs, under the hypothesis that such insights will shed light on a basic bacterial strategy for survival under conditions of varying sources of nutrition. ***The physiological activity of an enzyme depends upon the substrates it encounters in its environment. In Bt, many of the glycoside hydrolases receive their substrates through transport systems such as the starch utilization systems (SUS). We are embarking on studies of representative SUS molecular components. ***2. Fungal resistance to chitinase***When corn is infected by ear rot, an important agricultural fungal pathogen, it produces chitinases to combat the microbe. In response, the fungus produces a protease that is able to cleave the chitinase and permit the infection to continue. In the past grant period, we have been studying the ChitA chitinase. This will be extended in the next grant cycle to address the ChitB chitinase, with the goal of understanding their complementary activities and regulation. ***Recently, we have initiated studies of the fungal protease. These investigations will lead to insights into the mechanism by which the protease is induced and to approaches to combat ear rot in the field. ***Significance and Impact***This program is one of basic biochemical and molecular structure/function studies, as intended by the Discovery Grants program. It has both short term impact in deriving insights about important microbial activities, and also longer term insights into the dynamics of individual microbes and entire microbiota in response to environmental conditions. The resulting basic insights will have relevance to potential applications in microbial regulation of important processes. ******