1.M.7. The Phage Mu Spanin (Spanin7) Family 

Spanins are components of spanin complexes that disrupts the host outer membrane and causes cell lysis during virus exit. The spanin complex conducts the final step in host lysis by disrupting the outer membrane after holin and endolysin action have permeabilized the inner membrane and degraded the host peptidoglycan.  The phage Mu spanins were characterized by Chamblee et al. 2022.



Chamblee, J.S., J. Ramsey, Y. Chen, L.T. Maddox, C. Ross, K.H. To, J.L. Cahill, and R. Young. (2022). Endolysin Regulation in Phage Mu Lysis. mBio 13: e0081322.


TC#NameOrganismal TypeExample

Phage Mu spanin, Span1, of 128 aas and 1 N-terminal TMS. See Chamblee et al. 2022 for its identification. It may function with Span1.1. See the family description for more details. It is an inner membrane subunit, and its gene and protein designations are Mup23 and gp23.

Span1 of phage Mu


DUF2570 spanin of unknown function of 121 aas and one N-terminal TMS.

Spanin of Siphoviridae sp.


DUF2570 domain-containing protein of 130 aas and 1 N-terminal TMS.

DUF2570 domain protein of E. coli


Uncharacterized protein of 125 aas and 1 N-terminal TMS.

UP of Morganella morganii


DUF2570 domain-containing protein of 127 aas and 1 N-terminal TMS.

DUF2570 protein of Citrobacter portucalensis


DUF2570 domain-containing protein of 129 aas and 1 N-terminal TMS.

DUF2570 protein of Raoultella ornithinolytica