Complex O-acetylation in Legionella pneumophila serogroup 1 lipopolysaccharide. Evidence for two genes involved in 8-O-acetylation of legionaminic acid

Citation
O. Kooistra et al., Complex O-acetylation in Legionella pneumophila serogroup 1 lipopolysaccharide. Evidence for two genes involved in 8-O-acetylation of legionaminic acid, BIOCHEM, 40(25), 2001, pp. 7630-7640
Citations number
61
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMISTRY
ISSN journal
0006-2960 → ACNP
Volume
40
Issue
25
Year of publication
2001
Pages
7630 - 7640
Database
ISI
SICI code
0006-2960(20010626)40:25<7630:COILPS>2.0.ZU;2-0
Abstract
A putative gene encoding an O-acetyl transferase, lag-1, is involved in bio synthesis of the O-polysaccharide (polylegionaminic acid) in some Legionell a pneumophila serogroup 1 strains. To study the effect of the presence and absence of the gene on the O-polysaccharide O-acetylation, lag-1 from strai n Philadelphia I was expressed in trans in the naturally lag-1-negative OLD A strain RC1, and immunoblot analysis revealed that the lag-1-encoded O-ace tyl transferase is active. O-Polysaccharides of different size were prepare d from the lipopolysaccharides of wild-type and transformant strains by mil d acid degradation followed by gel-permeation chromatography. Using NMR spe ctroscopy and MALDI-TOF mass spectrometry, it was found that O-acetylation of the first three legionaminic acid residues next to the core occurs in th e short-chain O-polysaccharide (< 10 sugars) from both strains. Hence, ther e is another O-acetyl transferase encoded by a gene different from lag-1. I n the longer-chain O-polysaccharide, a legionaminic acid residue proximal t o the core is N-methylated and could be further 8-O-acetylated in the lag-1 -dependent manner. Only strains expressing a functional lag-1 gene were rec ognized in Western blot analysis by monoclonal antibody 3/1 requiring 8-O-a cetylated polylegionaminic acid for binding. The highly O-acetylated outer core region of the lipopolysaccharide is involved in the epitope of another serogroup 1-specific monoclonal antibody termed LPS-1. The O-acetylation p attern of the L. pneumophila serogroup 1 core oligosaccharide was revised u sing MALDI-TOF mass spectrometry. lag-1-independent O-acetylation of the co re and short-chain O-polysaccharide was found to be a common feature of L. pneumophila serogroup 1 strains. The biological importance of conserved lag -1-independent and variable lag-1-dependent O-acetylation is discussed.