Figure 3

PlcP often appears in an operon with a glycosyltransferase. (a) Genomic context of plcP. Numbers denote the six types of plcP genomic neighbourhood in representative marine heterotrophic bacteria (see Supplemantary Table S2 for further information). Asterisks indicate those genes with an upstream PhoB-binding site (Pho box) and therefore putatively expressed upon phosphorus deficiency. (b) Heterologous expression of the putative glycosyltransferase agt from SAR11 HTCC7211 results in the accumulation of two glycolipids: MGDG and GADG (dark grey bars) but not in the control harbouring an empty expression plasmid (light grey bars). Abundance is expressed as the peak area of glycolipid relative to that of a phosphatidylcholine internal standard. (c) Fragmentation spectra for representative MGDG and GADG species obtained from recombinant E. coli harbouring the HTCC7211 agt homologue. The two species differ in the neutral loss corresponding to the polar head group (179 and 193 m/z for the loss of hexosyl and hexuronic acid groups, respectively). In each case, this loss yields diacylglycerol (595 m/z). Two peaks corresponding to monoacylglycerol with 18:1 and 16:0 fatty acids (339 and 313 m/z, respectively) are also present.