Glutamate racemase; Provides the (R)-glutamate required for cell wall biosynthesis.

Outer membrane protein 1a (ia;b;f), porin; Forms pores that allow passive diffusion of small molecules across the outer membrane. It is also a receptor for the bacteriophage T2 (By similarity).

Outer membrane protein 1b (ib;c); Forms pores that allow passive diffusion of small molecules across the outer membrane.

Vitamin B12 transport protein; Part of the ABC transporter complex BtuCDF involved in vitamin B12 import. Involved in the translocation of the substrate across the membrane.

TonB; Interacts with outer membrane receptor proteins that carry out high-affinity binding and energy dependent uptake into the periplasmic space of specific substrates such as cobalamin, and various iron compounds (such as iron dicitrate, enterochelin, aerobactin, etc.). In the absence of TonB these receptors bind their substrates but do not carry out active transport. TonB also interacts with some colicins and is involved in the energy-dependent, irreversible steps of bacteriophages phi 80 and T1 infection. It could act to transduce energy from the cytoplasmic membrane to specific en [...]

Vitamin B12 transport protein; Part of the ABC transporter complex BtuCDF involved in vitamin B12 import. Responsible for energy coupling to the transport system.

B12-dependent homocysteine-N5-methyltetrahydrofolate transmethylase; Catalyzes the transfer of a methyl group from methyl- cobalamin to homocysteine, yielding enzyme-bound cob(I)alamin and methionine. Subsequently, remethylates the cofactor using methyltetrahydrofolate (By similarity).

Putative membrane component hydrogenase; With TolR probably plays a role in maintaining the position of the peptidoglycan cell wall in the periplasm. Acts as a porin with low permeability that allows slow penetration of small solutes; an internal gate slows down solute passage.