Involved in the degradation of the LPS-assembly protein LptD. Degrades LptD that have engaged the Bam complex but are stalled at an early step in the outer membrane protein assembly process. Binds 1 zinc ion per subunit. YcaL, BepA and DegP degrade stalled LptD substrate at distinct points in the outer membrane protein assembly. Belongs to the peptidase M48B family. Extended N-terminus.