Pyruvyl-transferases involved in peptidoglycan-associated polymer biosynthesis. CsaB in Bacillus anthracis is necessary for the non-covalent anchoring of proteins containing an SLH (S-layer homology) domain to peptidoglycan-associated pyruvylated polysaccharides. WcaK and AmsJ are involved in the biosynthesis of colanic acid in Escherichia coli and of amylovoran in Erwinia amylovora.