Illustration of the l0045- deleted mutant and genes flanking l0045. (B) Diagrams representing L0045-related constructs expressed from plasmids. Box indicates the open reading frame and the filled area marks a putative signal peptide in the N-terminal region of authentic L0045. In Δl0045, the segment encoding amino acid 37 to the C-terminus of L0045 was deleted by a facilitated homologous recombination method; as a result, an FRT scar was left in the recombination spot. L45_K3stop represents that the construct engineered in pQE_L45_K3stop has the third codon of l0045 (coding for Lys) mutated to TAG so that the downstream translation was forced to stop. L45_E42A is a construct where residue 42 at a predicted active site for transglycosylase was mutated; residue marked is: E, an authentic Glu; A, residue mutated to Ala. L45_NS, a non-secreted form of L0045 with residues 2-18 spanning the putative signal peptide deleted.