BioScience Trends. 2016;10(4):320-324. (DOI: 10.5582/bst.2016.01059)

Cloning, purification, crystallization and X-ray crystallographic analysis of the periplasmic sensing domain of Pseudomonas fluorescens chemotactic transducer of amino acids type A (CtaA).

Ud-Din AIMS, Roujeinikova A


Chemotaxis towards nutrients plays a crucial role in root colonization by Pseudomonas fluorescens. The P. fluorescens chemotactic transducer of amino acids type A (CtaA) mediates movement towards amino acids present in root exudates. In this study, the periplasmic sensory domain of CtaA has been crystallized by the hanging-drop vapor diffusion method using ammonium sulfate as a precipitating agent. A complete data set was collected to 1.9 Å resolution using cryocooling conditions and synchrotron radiation. The crystals belong to space group I222 or I212121, with unit-cell parameters a = 67.2, b = 76.0, c = 113.3 Å. This is an important step towards elucidation of the structural basis of how CtaA recognizes its signal molecules and transduces the signal across the membrane.

KEYWORDS: Bacterial chemotaxis, chemoreceptor, sensing domain, symbiosis

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