ジャーナル: Biochim Biophys Acta / 年: 2014 タイトル: The Salmonella enterica ZinT structure, zinc affinity and interaction with the high-affinity uptake protein ZnuA provide insight into the management of periplasmic zinc. 著者: Andrea Ilari / Flaminia Alaleona / Giancarlo Tria / Patrizia Petrarca / Andrea Battistoni / Carlotta Zamparelli / Daniela Verzili / Mattia Falconi / Emilia Chiancone / 要旨: BACKGROUND: In Gram-negative bacteria the ZnuABC transporter ensures adequate zinc import in Zn(II)-poor environments, like those encountered by pathogens within the infected host. Recently, the ...BACKGROUND: In Gram-negative bacteria the ZnuABC transporter ensures adequate zinc import in Zn(II)-poor environments, like those encountered by pathogens within the infected host. Recently, the metal-binding protein ZinT was suggested to operate as an accessory component of ZnuABC in periplasmic zinc recruitment. Since ZinT is known to form a ZinT-ZnuA complex in the presence of Zn(II) it was proposed to transfer Zn(II) to ZnuA. The present work was undertaken to test this claim. 手法: ZinT and its structural relationship with ZnuA have been characterized by multiple biophysical techniques (X-ray crystallography, SAXS, analytical ultracentrifugation, fluorescence spectroscopy). RESULTS: The metal-free and metal-bound crystal structures of Salmonella enterica ZinT show one Zn(II) binding site and limited structural changes upon metal removal. Spectroscopic titrations with ...RESULTS: The metal-free and metal-bound crystal structures of Salmonella enterica ZinT show one Zn(II) binding site and limited structural changes upon metal removal. Spectroscopic titrations with Zn(II) yield a KD value of 22±2nM for ZinT, while those with ZnuA point to one high affinity (KD<20nM) and one low affinity Zn(II) binding site (KD in the micromolar range). Sedimentation velocity experiments established that Zn(II)-bound ZinT interacts with ZnuA, whereas apo-ZinT does not. The model of the ZinT-ZnuA complex derived from small angle X-ray scattering experiments points to a disposition that favors metal transfer as the metal binding cavities of the two proteins face each other. CONCLUSIONS: ZinT acts as a Zn(II)-buffering protein that delivers Zn(II) to ZnuA. GENERAL SIGNIFICANCE: Knowledge of the ZinT-ZnuA relationship is crucial for understanding bacterial Zn(II) uptake.
SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW ... SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW IS ACTUALLY AN 8-STRANDED BARREL THIS IS REPRESENTED BY A 9-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL.
解像度: 2.52→50.57 Å / Cor.coef. Fo:Fc: 0.912 / Cor.coef. Fo:Fc free: 0.851 / SU B: 8.489 / SU ML: 0.199 / 交差検証法: THROUGHOUT / ESU R: 0.419 / ESU R Free: 0.337 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD / 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS.
Rfactor
反射数
%反射
Selection details
Rfree
0.32208
509
4.8 %
RANDOM
Rwork
0.23375
-
-
-
obs
0.23789
10068
96.91 %
-
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.4 Å / 溶媒モデル: MASK