PDB ID or protein name

1uun » Porin MspA

1uun » Porin MspA
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Topology in Bacterial Gram-positive outer membrane
Topologyout side
in side
1uun » Porin MspA
Hydrophobic Thickness 40.7 ± 2.1 Å
Tilt Angle 0 ± 0°
ΔGtransfer -71.0 kcal/mol
Links to 1uun PDB Sum, PDB, SCOP, MSD, OCA, MMDB
Topology subunit A (N-terminus out)
Resolution 2.50 Å
Other PDB entries representing this structure none
Number of TM Secondary Structures 16
8 transmembrane subunits
A - Tilt: 54° - Segments: 1(74-83), 2(111-119)
B - Tilt: 54° - Segments: 1(74-83), 2(111-119)
E - Tilt: 54° - Segments: 1(74-83), 2(111-119)
F - Tilt: 54° - Segments: 1(74-83), 2(111-119)
H - Tilt: 54° - Segments: 1(74-83), 2(111-119)
G - Tilt: 54° - Segments: 1(74-83), 2(111-119)
D - Tilt: 54° - Segments: 1(74-83), 2(111-119)
C - Tilt: 54° - Segments: 1(74-83), 2(111-119)
Experimental Verification for 1uun » Porin MspA
The calculated intrinsic hydrophobic thickness of the MspA stem domain is ~41 A. We consider this result be consistent with selective labeling of surface-exposed residues by membrane-impermeable probe (Mahfound et al., 2006). The 96A long MspA protrudes the OM, and its rim is exposed from the extracellular side, while the stem base is facing the periplasmic space. I was demonstrated that residues located in the stem part cannot be labeled when MspA is extracted from membranes but contains tightly-bound lipids (consistent with our calculations). However residues from the 30 A long part of the rim adjacent to barrel-barrels can be labeled in extracted proteins but are protected when porin remains in native membranes (Mahfound et al., 2006). This ~30 A long part of the rim may be protected from labeling in native membranes by the polysaccharide-rich outer layer that covers OM from outside, which is removed after protein extraction.