Characterization of the cassette containing genes for type 3 capsular polysaccharide biosynthesis in Streptococcus pneumoniae.

Abstract

SummaryThe capsular polysaccharide is the major virulence factor of Streptococcus pneumoniae. Previously, we identified and cloned a region from the S. pneumoniae chromosome specific for the production of type 3 capsular polysaccharide. Now, by sequencing the region and characterizing mutations genetically and in an in vitro capsule synthesis assay, we have assigned putative functions to the products of the type-specific genes. Using DNA from the right end of the region in mapping studies, we have obtained further evidence indicating that the capsule genes of each serotype are contained in a gene cassette located adjacent to this region. We have cloned the region flanking the left end of the cassette from the type 3 chromosome and have found that it is repeated in the S. pneumoniae chromosome. The DNA sequence and hybridization data suggest a model for recombination of the capsule gene cassettes that not only describes the replacement of capsule genes, but also suggests an explanation for binary capsule type formation, and the creation of novel capsule types.

Organization and characterization of the capsule biosynthesis locus of Streptococcus pneumoniae serotype 9V The GenBank accession number for the sequence reported in this paper is AF402095.

“…The genes are clustered within the chromosome and in all but one serotype (serotype 37) are located between dexB and aliA (Llull et al, 1999). At this time the CPS synthesis (cps) loci of 15 serotypes (1, 2, 3, 4, 6B, 8, 14, 18C, 19F, 19A, 19B, 19C, 23F, 33F and 37) have been sequenced (Arrecubieta et al, 1995 ;Dillard et al, 1995 ;Iannelli et al, 1999 ;Jiang et al, 2001 ;Kolkman et al, 1997b ;Llull et al, 1998Llull et al, , 1999Morona et al, 1997aMorona et al, , b, 1999aMunoz et al, 1997Munoz et al, , 1999. Sequence analysis and function predictions suggest that the loci contain the complete repertoire of genes specifically required for capsule biosynthesis and its regulation.…”

A Novel Pathway for O-Polysaccharide Biosynthesis in Salmonella enterica Serovar Borreze

“…Two of these proteins, Cps3S and HasA, are also predicted to be integral membrane proteins with similar hydropathy plots and four predicted transmembrane domains. Cps3S is a glycosyltransferase that directs the synthesis of the type 3 capsule of Streptococcus pneumoniae (45,46). The enzyme is bifunctional and processive, catalyzing the formation of [33)-␤-D-GlcA-(134)-␤-D-Glc- (13] n (45).…”

“…Cps3S is a glycosyltransferase that directs the synthesis of the type 3 capsule of Streptococcus pneumoniae (45,46). The enzyme is bifunctional and processive, catalyzing the formation of [33)-␤-D-GlcA-(134)-␤-D-Glc- (13] n (45). HasA is the hyaluronic acid synthase from Group A Streptococcus pyogenes (47,48).…”

Spontaneous sequence duplications within capsule genes cap8E and tts control phase variation in Streptococcus pneumoniae serotypes 8 and 37

“…The genetics of pneumococcal capsule biosynthesis has only recently started to become unravelled, and sequence data are available for a subset of the 90 serotypes (Dillard et al, 1995;Iannelli et al, 1999;Jiang et al, 2001;Kolkman et al, 1997a, b;Llull et al, 1998Llull et al, , 1999Morona et al, 1997aMorona et al, , b, 1999Munoz et al, 1997Munoz et al, , 1999Ramirez & Tomasz, 1998). Apart from two notable exceptions (serotypes 3 and 37) the majority of capsule loci are very similar in structure: a central region of serotype-specific genes (of varying number) is preceded by four genes thought to be involved in capsule regulation and export (Guidolin et al, 1994;Jiang et al, 2001;Morona et al, 2000) (Fig.…”