FIG 2.

Genetic and structural differences between serotypes 35C and 42. (A) Arrangement of structure-determining genes in the published cps loci of S. pneumoniae serotypes 35C (accession no. CR931706) and 42 (accession no. KY009533). The red “X” in wciG of cps42 reflects our finding in this study that wciG of serotype 42 is defective. (B) Comparison of nucleotide and amino acid sequences of wciG genes. The differences between the two sequences are highlighted in red. In cps42 of SP155, deletion of a single nucleotide “a” after nucleotide 16383 results in premature termination of WciG translation. Numbering is with respect to GenBank accession no. CR931706. (C) Complete structures of serotype 35C and 42 polysaccharides as determined by NMR spectroscopy. The uppercase letters in the structures indicate the residues whose ¹H and ¹³C chemical shifts are given in Table 3 and in the text. The sole difference between the two polysaccharides is the O-acetylation at 2-position of residue C, which is highlighted in red.