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Journal of Bacteriology, September 1999, p. 5355-5364, Vol. 181, No. 17
Molecular Microbiology Unit, Women's and
Children's Hospital, North Adelaide, South Australia
5006,1 and Department of Microbiology
and Immunology, University of Adelaide, Adelaide, South Australia
5005,2 Australia
Received 7 April 1999/Accepted 16 June 1999
The genetic basis for the structural diversity of capsule
polysaccharide (CPS) in Streptococcus pneumoniae serogroup
19 (consisting of types 19F, 19A, 19B, and 19C) has been determined for
the first time. In this study, the genetic basis for the 19A and 19C
serotypes is described, and the structures of all four serogroup 19 cps loci and their flanking sequences are compared.
Transformation studies show that the structural difference between the
19A and 19F CPSs is likely to be a consequence of differences between their respective polysaccharide polymerase genes (cps19aI
and cps19fI). The CPS of type 19C differs from that of type
19B by the addition of glucose. We have identified a single gene
difference between the two cps loci (cps19cS),
which is likely to encode a glucosyl transferase. The arrangement of
the genes within the cps19 loci is highly conserved, with
13 genes (cps19A to -H and cps19K
to -O) common to all four serogroup 19 members. These
cps genes encode functions required for the synthesis of
the shared trisaccharide component of the group 19 CPS repeat unit
structures. Furthermore, the genetic differences between the group 19 cps loci identified are consistent with the CPS structures
of the individual serotypes. Functions have been assigned to nearly all of the cps19 gene products, based on either gene
complementation or similarity to other proteins with known functions,
and putative biosynthetic pathways for production of all four group 19 CPSs have been proposed.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Comparative Genetics of Capsular Polysaccharide
Biosynthesis in Streptococcus pneumoniae Types Belonging to
Serogroup 19
*
Corresponding author. Mailing address: Molecular
Microbiology Unit, Women's and Children's Hospital, North Adelaide,
S.A., 5006, Australia. Phone: 61-8-82046302. Fax: 61-8-82046051. E-mail: patonj{at}wch.sa.gov.au.
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