Lipid A Mass Spectrometry raw data

To investigate the modification of lipid A by the predicted phosphoethanolamine transferase, MCR-12, thereby confirming the enzymatic function of MCR-12 as a phosphoethanolamine transferase. MCR-12 originated in Pigmentiphaga litoralis and comparisons made between the wild-type, and a strain variant where the plasmid carrying mcr-12 was cured. Additionally, mcr-12 was heterologously expressed in Escherichia coli TOP10 and Pseudomonas protegens Pf-5. The lipid A composition was examined for all of these strains. The data herein is the raw mzxML files.To extract lipid A, overnight 5 mL cultures of P. litoralis wild-type or plasmid-cured, and E. coli TOP10 or P. protegens Pf-5 with pBBR1MCS-2 or pBBR1MCS-2-mcr-12 were centrifuged (7,000 g, 5 min) and treated with 400 µL of 70% (v/v) isobutyric acid/1 M ammonium hydroxide at 100 °C for 45 min. The lysed contents were centrifuged (2,000 g, 15 min) and the supernatant was transferred to an equivalent volume of ultrapure water, and then dried overnight at ambient conditions in a rotary evaporator. The dried contents were washed twice in methanol prior to resuspension in 50-200 µL of 2 parts chloroform:1 part methanol: 0.25 parts water. Aliquots of extracted lipid A mixed with matrix norhamane were analysed using an UltrafleXtreme MALDI-TOF/TOF mass spectrometer (Bruker Daltonics Inc.), operated in negative reflection mode. Analyses were performed at 40% global intensity, and mass spectra were acquired from the sum of 5,000 laser shots from 5 separate positions using the following parameter set: Ion source 1: 20 kV; ion source 2: 17.8 kV; lens: 6.8 kV; reflector 1: 21.1 kV; reflector 2: 10.8 kV; pulsed ion extraction: 70 ns and detection gain: 7.7.