Modulation of the reactivity of multiheme cytochromes by site-directed mutagenesis: moving towards the optimization of microbial electrochemical technologies

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• 作者：Alexandra S. Alves ; Nazua L. Costa…
• 关键词：Shewanella oneidensis MR ; 1 ; Small tetraheme cytochrome ; Extracellular electron transfer ; Single amino ; acids mutations
• 刊名：JBIC Journal of Biological Inorganic Chemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：22
• 期：1
• 页码：87-97
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Biochemistry, general; Microbiology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1327
• 卷排序：22

文摘

Dissimilatory metal-reducing bacteria perform extracellular electron transfer, a metabolic trait that is at the core of a wide range of biotechnological applications. To better understand how these microorganisms transfer electrons from their metabolism to an extracellular electron acceptor, it is necessary to characterize in detail the key players in this process, the multiheme c-type cytochromes. Shewanella oneidensis MR-1 is a model organism for studying extracellular electron transfer, where the heme protein referred to as small tetraheme cytochrome is one of the most abundant multiheme cytochromes found in the periplasmic space of this bacterium. The small tetraheme cytochrome is responsible for the delivery of electrons to the porin–cytochrome supercomplexes that permeate the outer-membrane and reduce metallic minerals or electrodes. In this work, well-established thermodynamic and kinetic models that discriminate the electron transfer activity of the four individual hemes were employed to characterize a set of single amino-acid mutants of the small tetraheme cytochrome and their interaction with small inorganic electron donors and acceptors. The results show that electrostatics play an important role in the reactivity of the small tetraheme cytochrome with small inorganic electron partners, in particularly in the kinetics of the electron transfer processes. This thorough exploration using site-directed mutants provides key mechanistic insights to guide the rational manipulation of the proteins that are key players in extracellular electron transfer processes, towards the improvement of microbial electrochemical applications using dissimilatory metal-reducing bacteria.