| 1.B.16 The Short Chain Amide and Urea Porin (SAP) Family
The SAP family includes an outer membrane porin (FmdC) found in the bacterium Methylophilus methylotrophus. Its synthesis is inducible by short chain amides and urea, and the protein presumably transports these molecules across the outer membrane when these nitrogen sources are present at low concentrations. The protein is 390 amino acyl residues in length and consists largely of β-structure. It has only one homologue (25% identity), a protein found in Aquifex aeolicus (385 aas).
The generalized transport reaction catalyzed by FmdC is:
Amides (out)  Amides (periplasm)
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This family belongs to the Outer Membrane Pore-forming Protein I (OMPP-I) Superfamily .
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| References: |
Jahan, M.I., P. Juengwiwattanakitti, Y. Izu, R. Tobe, T. Imai, and H. Mihara. (2019). Selenite uptake by outer membrane porin ExtI and its involvement in the subcellular localization of rhodanese-like lipoprotein ExtH in Geobacter sulfurreducens. Biochem. Biophys. Res. Commun. 516: 474-479.
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Jahan, M.I., R. Tobe, and H. Mihara. (2018). Characterization of a Novel Porin-Like Protein, ExtI, from Geobacter sulfurreducens and Its Implication in the Reduction of Selenite and Tellurite. Int J Mol Sci 19:.
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Mills, J., N.R. Wyborn, J.A. Greenwood, S.G. Williams, and C.W. Jones. (1997). An outer-membrane porin inducible by short-chain amides and urea in the methylotrophic bacterium Methylophilus methylotrophus. Microbiology 143: 2373-2379.
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| Examples: |
| TC# | Name | Organismal Type | Example |
| 1.B.16.1.1 | Short chain amide porin, FmdC | Gram-negative bacteria | FmdC of Methylophilus methylotrophus |
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| 1.B.16.1.10 | Phosphate-selective porin | Nitrospira | Porin of Thioflavicoccus mobilis |
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| 1.B.16.1.11 | Putative porin | Synergistetes | Putative porin of Thermodesulfobacterium sp. (strain OPB45) |
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| 1.B.16.1.2 | Outer membrane porin FmdC or ExtI of 406 aas and 1 N-terminal TMS. The expression level of the extI gene did not respond to changes in osmolality and phosphate starvation.The only change due to an extI deficiency was a decreased ability to reduce selenite and tellurite (Jahan et al. 2018). This porin is responsible for the uptake of selenite and plays a role in the subcellular localization of the rhodanese-like lipoprotein, ExtH (Q748R1) (Jahan et al. 2019). | Bacteria | ExtI of Geobacter sulfurreducens |
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| 1.B.16.1.3 |
Outer membrane porin (Bhat et al. 2011). | Proteobacteria | TonB-dependent receptor of Myxococcus xanthus |
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| 1.B.16.1.4 | Putative outer membrane porin | Proteobacteria | OMP of Anaeromyxobacter dehalogenans |
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| 1.B.16.1.5 | Short chain amide porin | Aquificae | Amide porin of Hydrogenobaculum sp. HO |
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| 1.B.16.1.6 | Phosphate-selective porin O/P | Thermodesulfobacteria | Porin of Thermodesulfobacterium geofontis |
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| 1.B.16.1.7 | Phosphate-selective porin | Aquificae | Porin of Thermocrinis albus |
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| 1.B.16.1.8 | Phosphate-selective porin O/P | Chrysiogenetes | Omp O/P of Desulfurispirillum indicum |
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| 1.B.16.1.9 | Uncharacterized protein of 428 aas | Gemmatimnadetes | UP of Gemmatimonas aurantiaca |
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| Examples: |
| TC# | Name | Organismal Type | Example |
| 1.B.16.2.1 | Putative porin O | Bacteroidetes | Porin O of Flavobacterium indicum |
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| 1.B.16.2.2 | Putative porin of 451 aas | Spirochaetes | Putative porin of Leptospira biflexa |
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| 1.B.16.2.3 | Putative porin O/P of 413 aas. | Proteobacteria | Porin O/P of Geobacter sp. |
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| 1.B.16.2.4 | Phosphate-selective porin O/P of 421 aas | Acidobacteria | Porin of Holophaga foetida |
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| 1.B.16.2.5 | Putative porin | Acidobacteria | Porin of Terriglobus roseus |
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| 1.B.16.2.6 | Phosphate-specific porin O/P | Aquificae | Porin of Aquifex aeolicus |
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| 1.B.16.2.7 | Anion-selective porin of 581 aas | Nitrospira | Porin of Candidatus Nitrospira defluvii |
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| 1.B.16.2.8 | Putative porin of 579 aas | Planctomycetes | Porin of Rhodopirellula baltica |
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