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1.B.24.1.1
M. smegmatis porin, MspA (cation selective due to a high density of negative charges in the constriction zone, but it transports glucose, serine, hydrophilic β-lactams and (slowly) phosphate (Wolschendorf et al., 2007)) The MspC paralogue appears to have the same specificity as MspA. Both can also transport fluoroquinolones and chloramphenicol but not the larger erythromycin, kanamycin, and vancomycin (Danilchanka et al., 2008). Also allows uptake of ferric iron (Jones and Niederweis, 2010). The 3-d structure is known (PDB#1UUN). It is a β-barrel with N- and C-termini of their single hairpins on the outside, and their chains run in an anti-clockwise direction around the central pore. Both of these characteristics are opposite in most gram-negative bacterial β-barrels (Remmert et al., 2010).  Forms octameric voltage-gated nanopores where each subunit contributes 2 TMSs to the 16 stranded β-barrel (Faller et al. 2004; Rodrigues et al. 2011; Pavlenok et al. 2012) that can be used for nanopore sequencing (Pavlenok et al. 2012) that can be used for nanopore sequencing (Laszlo et al. 2016).

Accession Number:Q9RLP7
Protein Name:MspA
Length:211
Molecular Weight:22118.00
Species:Mycobacterium smegmatis [1772]
Number of TMSs:1
Location1 / Topology2 / Orientation3: Endoplasmic reticulum membrane1 / Multi-pass membrane protein2
Substrate cations, glucose, Serine, Beta-lactam antibiotics, phosphate, Fluoroquinolones, Chloramphenicol, Fe3+

Cross database links:

RefSeq: YP_885367.1   
Entrez Gene ID: 4533718   
Pfam: PF09203   

Gene Ontology

GO:0005576 C:extracellular region
GO:0051715 P:cytolysis of cells of another organism

References (2)

[1] “Cloning of the mspA gene encoding a porin from Mycobacterium smegmatis.”  Niederweis M.et.al.   10476028
[2] “The structure of a mycobacterial outer-membrane channel.”  Faller M.et.al.   14976314
Structure:
1UUN   2V9U     

External Searches:

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  • 2° Structure (Network Protein Sequence Analysis)

Analyze:

Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MKAISRVLIA MVAAIAALFT STGTSHAGLD NELSLVDGQD RTLTVQQWDT FLNGVFPLDR 
61:	NRLTREWFHS GRAKYIVAGP GADEFEGTLE LGYQIGFPWS LGVGINFSYT TPNILIDDGD 
121:	ITAPPFGLNS VITPNLFPGV SISADLGNGP GIQEVATFSV DVSGAEGGVA VSNAHGTVTG 
181:	AAGGVLLRPF ARLIASTGDS VTTYGEPWNM N