1.B.51 The Oms66 Porin (Oms66P) Family

Skare et al. (1997) reported the purification and characterization of a 66-kDa protein, designated Oms66, for outer membrane-spanning 66-kDa protein, that functions as a porin in the outer membrane (OM) of Borrelia burgdorferi. It exhibited an average single-channel conductance of 10 nS in 1 M KCl. Oms66 is virtually nonselective between cations and anions. Proteoliposomes containing Oms66 exhibit porin activity nearly identical to that of native, purified Oms66, indicating that reconstituted Oms66 retained native conformation (Skare et al., 1997).

The generalized reaction catalyzed by Oms66 is:

small molecules (out) small molecules (periplasm)



Barcena-Uribarri I., Thein M., Sacher A., Bunikis I., Bonde M., Bergstrom S. and Benz R. (2010). P66 porins are present in both Lyme disease and relapsing fever spirochetes: a comparison of the biophysical properties of P66 porins from six Borrelia species. Biochim Biophys Acta. 1798(6):1197-203.

Bárcena-Uribarri, I., M. Thein, E. Maier, M. Bonde, S. Bergström, and R. Benz. (2013). Use of nonelectrolytes reveals the channel size and oligomeric constitution of the Borrelia burgdorferi P66 porin. PLoS One 8: e78272.

Berry, J., M. Rajaure, T. Pang, and R. Young. (2012). The spanin complex is essential for lambda lysis. J. Bacteriol. 194: 5667-5674.

Curtis, M.W., B.L. Hahn, K. Zhang, C. Li, R.T. Robinson, and J. Coburn. (2018). Characterization of Stress and Innate Immunity Resistance of Wild-Type and Δ. Infect. Immun. 86:.

Kenedy MR., Luthra A., Anand A., Dunn JP., Radolf JD. and Akins DR. (2014). Structural modeling and physicochemical characterization provide evidence that P66 forms a beta-barrel in the Borrelia burgdorferi outer membrane. J Bacteriol. 196(4):859-72.

Skare, J.T., T.A. Mirzabekov, E.S. Shang, D.R. Blanco, H. Erdjument-Bromage, J. Bunikis, S. Bergström, P. Tempst, B.L. Kagan, J.N. Miller, and M.A. Lovett. (1997). The Oms66 (p66) protein is a Borrelia burgdorferi porin. Infect. Immun. 65: 3654-3661.

Summer, E.J., J. Berry, T.A. Tran, L. Niu, D.K. Struck, and R. Young. (2007). Rz/Rz1 lysis gene equivalents in phages of Gram-negative hosts. J. Mol. Biol. 373: 1098-1112.

Zhang, N. and R. Young. (1999). Complementation and characterization of the nested Rz and Rz1 reading frames in the genome of bacteriophage lambda. Mol. Gen. Genet. 262: 659-667.


TC#NameOrganismal TypeExample

Outer membrane-spanning porin, Oms66 (P66) (Skare et al., 1997).  This porin has a β-barrel structure (Kenedy et al. 2013) and pore diameters at the mouth of 1.6nm and at the central constriction of 0.8nm (Bárcena-Uribarri et al. 2013). Oms66 plays a role in resistance to host immune defenses (Curtis et al. 2018).


Oms66 of Borrelia burgdorferi (Q44881)