Structural remodelling of the carbon-phosphorus lyase machinery by a dual ABC ATPase

ABSTRACT Phosphorus is an essential macronutrient for all microorganisms and can be extracted from the environment by several metabolic pathways. In Escherichia coli, the 14-cistron phn operon encoding the carbon-phosphorus (C-P) lyase enzymatic machinery allows for extraction of phosphorus from a wide range of phosphonates characterised by the highly stable C-P bond. 1, 2 As part of a complex, multi-step pathway, the PhnJ subunit was proposed to cleave the C-P bond via a radical reaction, however, the details of the mechanism were not immediately compatible with the structure of the 220 kDa PhnGHIJ C-P lyase core complex, leaving a significant gap in our understanding of phosphonate breakdown in bacteria. 3, 4 Here we show using single-particle cryogenic-electron microscopy that PhnJ mediates binding of a unique double dimer of ATP-binding cassette (ABC) proteins, PhnK and PhnL to the core complex. ATP hydrolysis by PhnK induces drastic structural remodelling leading to opening of the core and reconfiguration of a metal-binding site located at the interface between the PhnI and PhnJ subunits. Our results offer new insights into the mechanism underlying C-P lyase and uncover a hitherto unknown configuration of ABCs that have wide-ranging implications for our understanding of the role of this module in biological systems.