A Cysteine Pair Controls Flavin Reduction by Extracellular Cytochromes during Anoxic/Oxic Environmental Transitions.
A Cysteine Pair Controls Flavin Reduction by Extracellular Cytochromes during Anoxic/Oxic Environmental Transitions.
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DOI：
10.1128/mbio.02589-22
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发表时间：
2023-02-28
期刊：
影响因子：
6.4
通讯作者：
Clarke TA
中科院分区：
文献类型：
--
作者：
Norman MP;Edwards MJ;White GF;Burton JAJ;Butt JN;Richardson DJ;Louro RO;Paquete CM;Clarke TA
希瓦氏菌属的许多细菌是兼性厌氧菌，能够减少广泛的可溶性和不溶性底物，包括Fe（III）矿物氧化物。在缺氧条件下，细菌Shewanella oneidensis MR-1使用孔蛋白-细胞色素复合物（Mtr）介导细胞外电子转移（EET）穿过外膜至细胞外底物。然而，目前还不清楚EET如何防止暴露于含氧环境时产生有害的活性氧（ROS）。Mtr复合物在缺氧和限氧条件下表达，并含有细胞外MtrC亚基。这有一个保守的CX 8 C基序，当去除时会抑制有氧生长。这种抑制作用是由ROS的增加引起的，ROS杀死了大部分的S。培养的oneidensis细胞。为了更好地理解这种作用，分离具有修饰的CX 8 C的可溶性MtrC同种型。在黄素单核苷酸（FMN）存在的情况下，这些亚型产生浓度增加的H2 O2，并大大增加了MtrC和FMN之间的亲和力。X射线晶体学显示，MtrC异构体的分子结构基本上没有变化，而小角X射线散射表明，灵活性的变化是负责控制FMN结合。总之，这些结果表明，在S. oneidensis MR-1由细胞色素表面上具有氧化还原活性的二硫键控制。在氧气存在下，形成二硫化物，降低对FMN的亲和力并降低过氧化物形成的速率。因此，这种半胱氨酸对允许细胞对氧水平的变化做出反应，并在快速转变的环境中生存。
Many bacteria of the genus Shewanella are facultative anaerobes able to reduce a broad range of soluble and insoluble substrates, including Fe(III) mineral oxides. Under anoxic conditions, the bacterium Shewanella oneidensis MR-1 uses a porin-cytochrome complex (Mtr) to mediate extracellular electron transfer (EET) across the outer membrane to extracellular substrates. However, it is unclear how EET prevents generating harmful reactive oxygen species (ROS) when exposed to oxic environments. The Mtr complex is expressed under anoxic and oxygen-limited conditions and contains an extracellular MtrC subunit. This has a conserved CX8C motif that inhibits aerobic growth when removed. This inhibition is caused by an increase in ROS that kills the majority of S. oneidensis cells in culture. To better understand this effect, soluble MtrC isoforms with modified CX8C were isolated. These isoforms produced increased concentrations of H2O2 in the presence of flavin mononucleotide (FMN) and greatly increased the affinity between MtrC and FMN. X-ray crystallography revealed that the molecular structure of MtrC isoforms was largely unchanged, while small-angle X-ray scattering suggested that a change in flexibility was responsible for controlling FMN binding. Together, these results reveal that FMN reduction in S. oneidensis MR-1 is controlled by the redox-active disulfide on the cytochrome surface. In the presence of oxygen, the disulfide forms, lowering the affinity for FMN and decreasing the rate of peroxide formation. This cysteine pair consequently allows the cell to respond to changes in oxygen level and survive in a rapidly transitioning environment.
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影响因子：
3.4
作者：
Bechtel TJ;Weerapana E
通讯作者：
Weerapana E
DOI：
10.1107/s2059798317016035
发表时间：
2018-02-01
期刊：
Acta crystallographica. Section D, Structural biology
影响因子：
--
作者：
Potterton L;Agirre J;Ballard C;Cowtan K;Dodson E;Evans PR;Jenkins HT;Keegan R;Krissinel E;Stevenson K;Lebedev A;McNicholas SJ;Nicholls RA;Noble M;Pannu NS;Roth C;Sheldrick G;Skubak P;Turkenburg J;Uski V;von Delft F;Waterman D;Wilson K;Winn M;Wojdyr M
通讯作者：
Wojdyr M
影响因子：
11.4
作者：
Shi, Zhi;Zachara, John M.;Fredrickson, Jim K.
通讯作者：
Fredrickson, Jim K.
影响因子：
3.2
作者：
Myers, CR;Myers, JM
通讯作者：
Myers, JM
影响因子：
6.1
作者：
Kozin, MB;Svergun, DI
通讯作者：
Svergun, DI