1.B.52 The Oms28 Porin (Oms28P) Family
Skare et al. (1996) described porin activity with single-channel conductances of 0.6 nS in 1 M KCI. Oms28 is a 257-amino-acid precursor protein with a putative 24-amino-acid leader peptidase I signal sequence. Processed Oms28 yielded a mature protein with a predicted molecular mass of 25,363 Da. When overproduced in Escherichia coli, the Oms28 porin fractionated in the outer membrane. Sodium dodecyl sulfate-polyacrylamide gel-purified recombinant Oms28 from E. coli retained functional activity as demonstrated by an average single-channel conductance of 1.1 nS in the planar lipid bilayer assay, confirming that Oms28 is a B. burgdorferi porin (Skare et al., 1996). The porin function of Oms28 (Bba74) has been questioned (Mulay et al. 2007). Regulation of its synthesis has been studied (Mulay et al. 2009). Much of the Oms28 sequence shows similarity with C-terminal regions of methylated chemotaxis proteins of bacteria.
The generalized reaction proposed to be catalyzed by Oms28 is:
small molecules (out) small moleules (in)
The outer membrane-spanning porin, Oms28 (Skare et al., 1996)
Putative porin of 289 aas
Putative porin of Borrelia garinii