Crystallization of an R‐Form Lipopolysaccharide from Klebsiella pneumoniae

Abstract

An R‐form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN‐111 (O3–:K1–) formed crystals, whose shapes were elongated hexagonal plates, trapezoid plates, and rhomboid plates, and whose greatest dimensions were 3.1 × 0.8 μm, when it was suspended in 50 mM Tris buffer at pH 8.5 containing 5 mM MgCl2 and kept at 4 C for as long as 870 days. K. pneumoniae LEN‐111 synthesized LPS molecules possessing incomplete repeating units of the O‐antigenic polysaccharide portion besides the R‐form LPS because of a leaky characteristic, but crystals consisted exclusively of the R‐form LPS. Although the size of crystals was not large enough for X‐ray analysis and limited crystallographic information was available, it was suggested that the crystals consist of hexagonal lattices with an a axis of 4.62 Å and c axis of 79.8 ±2.6 Å. The present results showed that R‐form LPS lacking the O‐antigenic polysaccharide portion tends to form crystals during long‐term incubation in Tris buffer at pH 8.5 containing MgCl2 at 4 C.

Molecular structure of bacterial endotoxin (Escherichia coli Re lipopolysaccharide): implications for formation of a novel heterogeneous lattice structure

“…Previously, we have demonstrated that various chemotypes of R‐form LPS from E. coli and Salmonella spp. (Kato et al ., 1990a, b; 1993; 1994; 1996b; Kato, 1993) and synthetic E. coli ‐type lipid A (Kato et al ., 1996a) form three‐dimensional crystals, the basic form of which is the hexagonal plates, when they were precipitated by the addition of two volumes of 95% ethanol containing 375 mM MgCl 2 . Although the study was the first one that demonstrated the formation of crystals of LPS, the size of crystals formed under these experimental conditions was not large enough for analysis by X‐ray diffraction.…”