Required for tail assembly of phage Mu and responsible for circularizing the viral DNA after it has been ejected into the host cell. Following infection, the circularized DNA can be isolated as a supercoiled, non-covalent protein-DNA complex, in which the protein N is bound to the ends of the DNA. Protects linear double-stranded DNA of viral genome from host exonuclease degradation. Part of a complex composed of three DNA circularization protein N, three baseplate hub protein gp44 and three sub-complex wedge (made of two copies of each baseplate protein gp46, gp47 and gp48) that forms the baseplate. Baseplate protein. Expressed in the late phase of the viral replicative cycle. Expression of late genes is activated by the viral late transcription activator C. LysM-like fold region might interact with peptidoglycan to facilitate DNA ejection. No tail is synthesized.