PDB ID or protein name

1uun » Porin MspA

1uun » Porin MspA
Magnify 1uun » Porin MspAEnlarged view of image
3D view in Jmol or Webmol

gray dot

Download Coordinates

gray dot

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 Å. We consider this result be consistent with selective labeling of surface-exposed residues by membrane-impermeable probe (Mahfound et al., 2006). The 96-Å 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-Å long part of the rim adjacent to β-barrels can be labeled in extracted proteins but are protected when porin remains in native membranes (Mahfound et al., 2006). This ~30-Å 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.