Dynamic microbial molecular activities

微生物几乎存在于地球上的每个生态系统中。微生物区系的组成在其环境中扮演着重要的功能角色。微生物区系组成的相对组成可以是动态的；它们可以根据营养来源、感染和其他因素而变化。本程序的目标是调查一些从其功能中预期为动态的组件。*1.细菌糖苷水解酶*上一批赠款的主要关注点是对营养来源变化作出反应的细菌酶。我们一直致力于研究拟杆菌属(Bt)的糖苷水解酶。我们有兴趣了解Bt进化出如此庞大的GHS谱系的原因，这是在这样的假设下进行的，即这些见解将阐明在不同营养来源条件下生存的基本细菌策略。*酶的生理活性取决于它在环境中遇到的底物。在Bt中，许多糖苷水解酶通过淀粉利用系统(SUS)等运输系统获得底物。我们正在着手研究具有代表性的SUS分子组成。*2.真菌对几丁质酶的抗性*当玉米被一种重要的农业真菌病原体--穗腐病侵染时，它会产生几丁质酶来对抗微生物。作为回应，真菌产生一种能够裂解几丁质酶的蛋白酶，并允许感染继续下去。在过去的资助期间，我们一直在研究几塔几丁质酶。这将在下一个赠款周期中延长，以解决ChitB几丁质酶，目的是了解它们的互补活动和调节。*最近，我们开始了对真菌蛋白水解酶的研究。这些研究将引导人们深入了解蛋白酶的诱导机制，并找到在田间防治耳腐病的方法。*意义和影响*本计划是探索基金计划的基本生化和分子结构/功能研究之一。它既有对重要微生物活动的洞察的短期影响，也有对单个微生物和整个微生物区系对环境条件作出反应的动态的长期洞察。由此产生的基本见解将与重要过程的微生物调控的潜在应用相关。******

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. ******