FIG. 7.
Mass spectroscopy of the lipid A from pmrF, pmrI, pmrK, pmrL, and pmrM nonpolar deletion strains. The m/z ratios and related structures are as follows: 1,797, unmodified hexa-acyl lipid A; 1,815, hexa-acyl lipid A with 2-OH myristate; 1,929, hexa-acyl lipid A with Ara4N; 1,949, hexa-acyl lipid A with 2-OH myristate and Ara4N; 2,036, unmodified hepta-acyl lipid A; 2,052, hepta-acyl lipid A with 2-OH myristate; 2,167, hepta-acyl lipid A with Ara4N; 2,189, hepta-acyl lipid A with 2-OH myristate and Ara4N. The lipid A from strains with pmrH and pmrJ nonpolar deletions was also examined, and the results were identical to those shown in panels A through D but were not included due to differences in the scale of m/z values examined and the difficulty in comparing these tracings to those for the other samples. The PmrAc strain that is the parental background of the strains with the examined deletions has been examined previously (8), and results for it are identical to those shown in panel E.