Bioinformatic analysis of Beta barrel porins: Structural Analysis of Outer Membrane Beta-stranded Porins using Temperature Factor

Outer membrane beta-stranded porins form a diverse and complex set of proteins which allow passage of molecules across the membrane interface have been analyzed here from a biophysical and structural perspective using atomic temperature factors or B-factors. Structures of six porins (four 16 stranded beta barrel porins and two 8 stranded beta barrel porins) were taken from the PDB for the analysis based on resolution (better than 3.0 Ã…) and R-factor (< 0.23). The residue distribution and mobility distribution was found to be characteristic of each of the porins. The mobility and residue distribution amongst the secondary structural elements were found to follow the level of homology at the sequence and structural level. For both the 16 stranded and the 8 stranded barrels it was found one part of the barrel was more rigid and the other half of the barrel showed more mobility as seen from the temperature factors. This seems to be an intrinsic structural component of the beta barrels.