Analysis of the Structure and Biosynthesis of the Lipopolysaccharide Core Oligosaccharide of pv. DC3000.

Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is important for bacterial viability in general and host-pathogen interactions in particular. Negative charges at its core oligosaccharide (core-OS) contribute to membrane integrity through bridging interactions with divalent cations. The molecular structure and synthesis of the core-OS have been resolved in various bacteria including the mammalian pathogen . A few core-OS structures of plant-associated strains have been solved to date, but the genetic components of the underlying biosynthesis remained unclear. We conducted a comparative genome analysis of the core-OS gene cluster in pv. () DC3000, a widely used model pathogen in plant-microbe interactions, within the species complex and to other plant-associated strains. Our results suggest a genetic and structural conservation of the inner core-OS but variation in outer core-OS composition within the species complex. Structural analysis of the core-OS of DC3000 shows an uncommonly high phosphorylation and presence of an O-acetylated sugar. Finally, we combined the results of our genomic survey with available structure information to estimate the core-OS composition of other species.