Identification of new members of the lytic transglycosylase family in Haemophilus influenzae and Escherichia coli.

Although bacterial peptidoglycan metabolism and numerous of the enzymes involved therein have been studied extensively over the years, information on the precise number of these enzymes is still lacking as is knowledge on the specific function of most of them. This observation holds true even for the well-studied bacterium Escherichia coli. Through determination of the complete sequences of bacterial genomes, that of Haemophilus influenzae being the first example, the opportunity arises to obtain a comprehensive overview of the members of the different families of peptidoglycan metabolizing enzymes by identification of their genes. Following this rationale, H. influenzae and E. coli genomic sequence was searched for new members of the family of lytic transglycosylases, using three-dimensional structure-derived sequence information. A new putative lytic transglycosylase gene could be identified in both bacterial species. The gene from E. coli was cloned and peptidoglycan hydrolase activity was demonstrated for the gene product.