Insights into the structure-function relationship of the NorQ/NorD chaperones from Paracoccus denitrificans reveal shared principles of interacting MoxR AAA+/VWA domain proteins

Table 2 NOR activity and non-heme Fe content in membranes from pNOREX variants

*nor* operon modification (pNOREX-His)	cNOR activity (%)	cNOR non-heme Fe content (%)
WT	100^a	100^a
ΔnorQDEF	0.4^a	20±7^a
E109Q (NorQ)	3±3 (n=2)	ND
T534V (NorD)	2±2 (n=2)	ND
D562N (NorD)	4±1 (n=2)	ND
E75A/E78A (NorB)	40±10 (n=6)	ND
D220A (NorB)	4±3 (n=2)	28±3 (n=3)
E222A (NorB)	4±2 (n=2)	24±9 (n=3)
N-terminal His tag (NorD)	70±5 (n=3)	ND
N-terminal His tag (NorQ)	80±20 (n=3)	ND

NO reduction activity was measured in detergent solubilized membranes. Experimental conditions: 25 nM cNOR in 50 mM Hepes, pH 7.5, 50 mM KCl, 1 % DDM, 10 μM horse heart cyt. c, 500 μM TMPD and 3 mM ascorbate at 22 °C. The non-heme Fe content was measured with purified cNOR. Data (see Additional file 4) presented as averages with standard error
ND not determined
^aThe data for WT and ΔnorQDEF was published previously [2]

ISSN: 1741-7007