*1.B.44 The Probable Protein Translocating Porphyromonas gingivalis* Porin (PorT) Family** The Gram-negative priodontopathogenic bacterium, Porphyromonas gingivalis, secretes proteinases (gingipains) and adhesin complexes as virulence factors to the cell surface or external milieu. Mutants in the porT gene showed weak gingipain activities in cell lysates. The precursor forms of gingipains and the adhesins accumulated in the periplasm and lacked the N-terminal signal peptide regions. However, they were not further processed. The final processing steps are known to occur after passage of the proteins through the outer membrane on the cell surface. Products of the kgp, rgpA, rgpB and hagA genes are all apparently exported across the outer membrane via PorT. It is not known if other constituents play a role (Sato et al., 2005). PorT has 244 aas, a strongly hydrophobic leader sequence (hydrophobic TMS at residues 9-27), and 8 amphipathic transmembrane β-strands (Nguyen et al., 2009). It is homologous throughout most of its length with a hypothetical protein (Chut02002746; BAA36600) from Cytophaga hutchinsonii (225 aas; 33% identity, 54% similarity; e^-21).
This family belongs to the Outer Membrane Pore-forming Protein I (OMPP-I) Superfamily .
References:
Nguyen, K.A., J. Zylicz, P. Szczesny, A. Sroka, N. Hunter, and J. Potempa. (2009). Verification of a topology model of PorT as an integral outer-membrane protein in Porphyromonas gingivalis. Microbiology 155: 328-337.
Sato, K., E. Sakai, P.D. Veith, M. Shoji, Y. Kikuchi, H. Yukitake, N. Ohara, M. Naito, K. Okamoto, E.C. Reynolds, and K. Nakayama. (2005). Identification of a new membrane-associated protein that influences transport/maturation of gingipains and adhesins of Porphyromonas gingivalis. J. Biol. Chem. 280: 8668-8677.
Examples:
TC#	Name	Organismal Type	Example
1.B.44.1.1	*The putative PorT porin (Sato et al., 2005)*	Bacteriodetes	*PorT of Porphyromonas gingivalis* (BAA36600)**

1.B.44.1.2	Putative porin	Bacteroidetes	Putative porin of Prevotella buccae

1.B.44.1.3	Putative porin	Bacteroidetes	Putative porin of Cytophaga hutschinsonii

1.B.44.1.4	Putative porin	Bacteroidetes	Putative porin of Chryseobacterium gleum

1.B.44.1.5	PorT homologue of 276 aas	Bacteroidetes	PorT homologue of Sphingobacterium spiritivorum

Examples:
TC#	Name	Organismal Type	Example
1.B.44.2.1	Putative porin	Bacteroidetes	Putative porin on Flavobacterium johnsoniae

1.B.44.2.10	Uncharacterized protein of 212 aas	Bacteroidetes	UP of Marivirga tractuosa (Microscilla tractuosa) (Flexibacter tractuosus)

1.B.44.2.11	Uncharacterized protein of 202 aas	Bacteroidetes	UP of Bacteroides salanitronis

1.B.44.2.12	Uncharacterized protein of 228 aas	Proteobacteria	UP of Haliangium ochraceum

1.B.44.2.13	Uncharacterized protein of 301 aas	Bactereoidetes	UP of Salinibacter ruber

1.B.44.2.14	Uncharacterized protein of 193 aas	Proteobacteria	UP of Bdellovibrio bacteriovorus

1.B.44.2.15	Uncharacterized protein of 243 aas	Bacteroidetes	UP of Porphyromonas gingivalis

1.B.44.2.16	Uncharacterized protein of 211 aas.	Bacteroidetes	UP of Rhodothermus marinus (Rhodothermus obamensis)

1.B.44.2.17	Uncharacterized protein of 218 aas	Proteobacteria	UP of Aliivibrio salmonicida (Vibrio salmonicida)

1.B.44.2.18	Putative porin of 224 aas	Bacteroidetes	UP of Spirosoma linguale

1.B.44.2.2	Putative porin of 229 aas and 10 putative beta strands.	Bacteroidetes	PP of Riemerella anatipestifer

1.B.44.2.3	Uncharacterized protein of 207 aas	Bacteroidetes	UP of Nonlabens dokdonensis (Donghaeana dokdonensis)

1.B.44.2.4	Uncharacterized protein of 256 aas	Fibrobacteres	UP of Fibrobacter succinogenes

1.B.44.2.5	Uncharacterized protein of 210 aas	Bacteroidetes	UP of Paludibacter propionicigenes

1.B.44.2.6	Uncharacterized protein of 194 aas	Bacteroidetes	UP of Belliella baltica

1.B.44.2.7	Uncharacterized protein of 194 aas	Bcteroidetes	UP of Leadbetterella byssophila

1.B.44.2.8	Uncharacterized protein of 227 aas	Bacteroidetes	UP of Haliscomenobacter hydrossis

1.B.44.2.9	Uncharacterized protein of 218 aas	Bacteroidetes	UP of Alistipes finegoldii