Phosphatidylcholine absence affects the secretion of lipodepsipeptide phytoxins in Pseudomonas syringae pv. syringae van Hall CFCC 1336

In this study, we further analyzed virulence of lipodepsipeptide phytoxins of Pss 1336 wild type (pcs +), the 1336RM (pcs−/+) and the 1336 pcs− mutant, and found that the 1336 pcs− mutant was unable to cause necrosis of Chinese date fruits and inhibit fungal growth. HPLC analysis also showed that the 1336 pcs− mutant markedly reduced its secretion of lipodepsipeptide phytoxins. Analysis of semi-quantitative RT-PCR revealed that PC presence or absence did not affect gene expressions of SyrD, PseABC and PseEF efflux systems at transcriptional level. However, western blotting assays found that PseE and PseF present only in the cytoplasmic fractions but undetectable in the membrane extract of the 1336 pcs− mutant. PC absence obviously interrupted the translocation of two membrane-associated proteins PseE and PseF from cytoplasm to cell membranes to form an intact PseEF efflux system in bacterial membranes. Failure to form PseEF efflux system could be a major factor for less lipopeptide-phytoxin secretion. Our results demonstrate that PC in bacterial membrane phospholipids plays an important role in maintaining physiological functions of PseEF efflux system.
Source: Microbiological Research - Category: Infectious Diseases Source Type: research