Pl. Deangelis et al., IDENTIFICATION AND MOLECULAR-CLONING OF A UNIQUE HYALURONAN SYNTHASE FROM PASTEURELLA-MULTOCIDA, The Journal of biological chemistry, 273(14), 1998, pp. 8454-8458
Type A Pasteurella multocida, a prevalent animal pathogen, employs a h
yaluronan [HA] polysaccharide capsule to avoid host defenses, We utili
zed transposon insertional mutagenesis to identify the P. multocida HA
synthase, the enzyme that polymerizes HA. A DNA fragment from a wild-
type genomic library could direct HA production in vivo in Escherichia
coli, a bacterium that normally does not produce HA. Analysis of trun
cated plasmids derived from the original clone indicated that an open
reading frame encoding a 972-residue protein was responsible for HA po
lymerization, This identification was confirmed by expression cloning
in E. coli; we observed HA capsule formation in vivo and detected acti
vity in membrane preparations in vitro, The polypeptide size was verif
ied by photoaffinity labeling of the native P. multocida HA synthase w
ith azido-UDP sugar analogs, Overall, the P. multocida sequence is not
very similar to the other known HA synthases from streptococci, PBCV-
1 virus, or vertebrates. Instead, a portion of the central region of t
he new enzyme is more homologous to the amino termini of other bacteri
al glycosyltransferases that produce different capsular polysaccharide
s or lipopolysaccharides. In summary, rye have discovered a unique HA
synthase that differs in sequence and predicted topology from the othe
r known enzymes.