Toxic component of a toxin-immunity protein module, which functions as a cellular contact-dependent growth inhibition (CDI) system. A site-specific general tRNA nuclease, the C-terminus (residues 2201-2334) removes 2 or 4 nucleotides from the 3' end of at least 4 tRNAs (upon expression in E.coli), possibly endonucleolytically. The nuclease activity is neutralized by expression of the cognate immunity protein WapI from the same strain, but not its homolog from 2 other B.subtilis strains. The C-terminus cannot be expressed on its own in E.coli, however it can be cloned in the presence of its cognate immunity protein gene. Cell contact is necessary for growth inhibition (PubMed:23572593). Unlike the LXG toxin-immunity modules, WapAI mediates competition under shaking culture conditions (PubMed:34280190). Detected in exponentially growing cells as many processing products, protein disappears upon entry into stationary phase with the concomitant appearance of smaller products. The large products persist in the absence of the extracellular serine protease Epr (PubMed:11987133). Probably exported by a SecA-dependent pathway. Constitutively and highly expressed on solid and in liquid medium, with or without biofilm formation, by 12 hours of culture. Repressed by DegU. Has two ligand-binding domains; the N-terminus has three 101 AA repeats which are responsible for cell wall binding; the C-terminus consists of two blocks of residues with a conserved motif repeated 31 times. Identified in the extracellular proteome as many processing products ranging from over 85 kDa to about 30 kDa. One of these probably starts on Ser-1726. Two forms are known as CWBP62 and CWBP105 (PubMed:11987133). A double wapA-wapI deletion strain is growth inhibited when cocultured with wild-type cells. When wapI is reintroduced it restores growth in a cognate toxin-dependent fashion (PubMed:23572593). Growth inhibition by wild-type cells is strongest on LB medium and less effective on media that promote biofilm formation (MSgg and 2xSGG) (PubMed:34280190). Belongs to the RHS/WapA nuclease family.