DNA polymorphism analysis of Brucella lipopolysaccharide genes reveals marked differences in O-polysaccharide biosynthetic genes between smooth and rough Brucella species and novel species-specific markers.
BACKGROUND
The lipopolysaccharide is a major antigen and virulence factor of Brucella, an important bacterial pathogen. In smooth brucellae, lipopolysaccharide is made of lipid A-core oligosaccharide and N-formylperosamine O-polysaccharide. B. ovis and B. canis (rough species) lack the O-polysaccharide.


RESULTS
The polymorphism of O-polysaccharide genes wbkE, manA(O-Ag), manB(O-Ag), manC(O-Ag), wbkF and wbkD) and wbo (wboA and wboB), and core genes manB(core) and wa** was analyzed. Although most genes were highly conserved, species- and biovar-specific restriction patterns were found. There were no significant differences in putative N-formylperosamyl transferase genes, suggesting that Brucella A and M serotypes are not related to specific genes. In B. pinnipedialis and B. ceti (both smooth), manB(O-Ag) carried an IS711, confirming its dispensability for perosamine synthesis. Significant differences between smooth and rough species were found in wbkF and wbkD, two adjacent genes putatively related to bactoprenol priming for O-polysaccharide polymerization. B. ovis wbkF carried a frame-shift and B. canis had a long deletion partially encompassing both genes. In smooth brucellae, this region contains two direct repeats suggesting the deletion mechanism.


CONCLUSIONS
The results define species and biovar markers, confirm the dispensability of manB(O-Ag) for O-polysaccharide synthesis and contribute to explain the lipopolysaccharide structure of rough and smooth Brucella species.
Zygmunt
Michel S
MS
INRA, UR1282, Infectiologie Animale et Santé Publique, IASP, Nouzilly, France. mzygmunt@tours.inra.fr
Blasco
José M
JM
Letesson
Jean-Jacques
JJ
Cloeckaert
Axel
A
Moriyón
Ignacio
I
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D015415:Biomarkers; D002002:Brucella / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006595:Hexosamines / Q000235:genetics; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D009713:Nucleotidyltransferases / Q000235:genetics; D019081:O Antigens / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
C098054:4-formamido-4,6-dideoxymannose; D001426:Bacterial Proteins; D015415:Biomarkers; D004269:DNA, Bacterial; D006595:Hexosamines; D009097:Multienzyme Complexes; D019081:O Antigens; C093300:ManB protein, bacteria; D009713:Nucleotidyltransferases; D008359:Mannose-6-Phosphate Isomerase