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首页> 外文期刊>Biochemistry >Structural Studies of Bacterioferritin B from Pseudomonas aeruginosa Suggest a Gating Mechanism for Iron Uptake via the Ferroxidase Center,
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Structural Studies of Bacterioferritin B from Pseudomonas aeruginosa Suggest a Gating Mechanism for Iron Uptake via the Ferroxidase Center,

机译：铜绿假单胞菌细菌铁蛋白B的结构研究表明，通过铁氧化酶中心吸收铁的门控机制，

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摘要

The structure of recombinant Pseudomonas aeruginosa bacterioferritin B (Pa BfrB) has beenndetermined from crystals grown from protein devoid of core mineral iron (as-isolated) and from proteinnmineralized with ∼600 iron atoms (mineralized). Structures were also obtained from crystals grown fromnmineralized BfrB after they had been soaked in an FeSO4 solution (Fe soak) and in separate experiments afternthey had been soaked in an FeSO4 solution followed by a soak in a crystallization solution (double soak).nAlthough the structures consist of a typical bacterioferritin fold comprised of a nearly spherical 24-mernassembly that binds 12 heme molecules, comparison of microenvironments observed in the distinct structuresnprovided interesting insights. The ferroxidase center in the as-isolated, mineralized, and double-soaknstructures is empty. The ferroxidase ligands (except His130) are poised to bind iron with minimalnconformational changes. The His130 side chain, on the other hand, must rotate toward the ferroxidasencenter to coordinate iron. In comparison, the structure obtained from crystals soaked in an FeSO4 solutionndisplays a fully occupied ferroxidase center and iron bound to the internal, Fe(in), and external, Fe(out),nsurfaces of Pa BfrB. The conformation of His130 in this structure is rotated toward the ferroxidase center andncoordinates an iron ion. The structures also revealed a pore on the surface of Pa BfrB that likely serves as anport of entry for Fe2þnto the ferroxidase center. On its opposite end, the pore is capped by the side chain ofnHis130 when it adopts its “gate-closed” conformation that enables coordination to a ferroxidase iron.nA change to its “gate-open”, noncoordinative conformation creates a path for the translocation of iron fromnthe ferroxidase center to the interior cavity. These structural observations, together with findings obtainednfrom iron incorporation measurements in solution, suggest that the ferroxidase pore is the dominant entry routenfor the uptake of iron by Pa BfrB. These findings, which are clearly distinct from thosemade with Escherichia colinBfr [Crow, A. C., Lawson, T. L., Lewin, A., Moore, G. R., and Le Brun, N. E. (2009) J. Am. Chem. Soc. 131,n6808-6813], indicate that not all bacterioferritins operate in the same manner.
机译：重组铜绿假单胞菌细菌铁蛋白B（Pa BfrB）的结构是由不含核心矿铁的蛋白质（原样）和经约600个铁原子矿化的蛋白质中结晶而成的。从矿化的BfrB中生长的晶体在浸泡在FeSO4溶液中（Fe浸泡）后，再在单独的实验中先浸泡在FeSO4溶液中，然后浸泡在结晶溶液中（两次浸泡），也可以得到晶体的结构。由典型的细菌铁蛋白折叠组成，该折叠由结合了12个血红素分子的近球形24 Mern装配组成，在不同结构中观察到的微环境的比较提供了有趣的见解。分离的，矿化的和双浸泡结构中的铁氧化酶中心是空的。铁氧化酶配体（His130除外）准备以最小的构象变化结合铁。另一方面，His130侧链必须向铁氧体中心旋转，以协调铁。相比之下，从浸泡在FeSO4溶液中的晶体获得的结构显示出一个完全占据的铁氧化酶中心，并且铁与Pa BfrB的内部Fe（in）和外部Fe（out）n表面结合。该结构中的His130的构象向铁氧化酶中心旋转并配位铁离子。该结构还揭示了Pa BfrB表面的孔，该孔可能是Fe2→n进入铁氧化酶中心的入口。在其相反的一端，当孔采用“门关闭”构型时，其孔被nHis130的侧链封盖，从而能够与铁氧化酶铁配合。nA变为“门打开”时，非配位构型为易位形成了一条路径铁从氧化亚铁酶中心到内腔。这些结构性观察以及从溶液中铁掺入量测量中获得的发现表明，铁氧过氧化物酶孔是Pa BfrB吸收铁的主要进入途径。这些发现明显不同于用大肠杆菌（Escherichia colinBfr）所作的发现[Crow，A.C.，Lawson，T.L.，Lewin，A.，Moore，G.R。，和Le Brun，N.E。（2009）J.Am.Chem.Soc。，66，1593（1989）。化学Soc。 131，n6808-6813]表示并非所有细菌铁蛋白都以相同的方式起作用。

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  • 来源
    《Biochemistry》 |2010年第6期|p.1160-1175|共16页
  • 作者

    Saroja K. Weeratunga Scott Lovell Huili Yao Kevin P. Battaile Christopher J. Fischer Casey E. Gee and Mario Rivera;

  • 作者单位

    §Ralph N. Adams Institute for Bioanalytical Chemistry and Department of Chemistry, University of Kansas, MultidisciplinaryResearch Building, 2030 Becker Drive, Room 220 E, Lawrence, Kansas 66047,)Structural Biology Center, University of Kansas,2121 Simons Drive, Lawrence, Kansas 66047, ^Department of Physics and Astronomy, 1251 Wescoe Hall Drive, Malott Hall,Lawrence, Kansas 566045, and @IMCA-CAT, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue,Building 435A, Argonne, Illinois 60439;

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