Crystal structure of Omp32, the anion-selective porin from Comamonas acidovorans, in complex with a periplasmic peptide at 2.1 Å resolution

Abstract

The Omp32 structure explains the strong anion selectivity of this porin. Selectivity is conferred by a positive potential, which is not attenuated by negative charges inside the channel, and by an extremely narrow constriction zone. Moreover, Omp32 represents the anchor molecule for a peptide which is homologous to proteins that link the outer membrane to the cell wall peptidoglycan.

The Core of the Tetrameric Mycobacterial Porin MspA Is an Extremely Stable β-Sheet Domain

“…Therefore, IR absorbance spectra of MspA were analyzed for the spectral components of the amide I band region (1700 -1600 cm Ϫ1 ), which is indicative for the secondary structure of proteins (26), and compared with that of porin Omp32 from Delftia (Comamonas) acidovorans. The latter has a ␤-sheet content of 61% as derived from its atomic structure (27). IR spectral analysis of Omp32 yielded a ␤-sheet content of 59%, in excellent agreement with the structural data.…”

“…This also excludes a tertiary structure similar to that of TolC, where three monomers are intertwined to form one central channel (14). (ii) The intersubunit contact in trimeric porins such as OmpF from E. coli or Omp32 from D. acidovorans and others is mainly stabilized by hydrophobic interactions and salt bridges, as can be derived from their atomic structures (27,29). Disruption of the hydrophobic interactions by SDS consequently reduced the denaturation temperature of OmpF by 15-20°C compared with the nonionic and less aggressive detergent octyl glucoside (28).…”

Structural basis for solute transport, nucleotide regulation, and immunological recognition of Neisseria meningitidis PorB

“…1 B and C) identifies a putative pathway on the pore face nearest the crystallographic 3-fold axis that is lined with positively charged residues. A similar feature has been identified in the Escherichia coli OmpF (34,35), the Delfita acidovorans Omp32 (36,37), and the E. coli OmpC (38), which all share structural similarity to PorB in the transmembrane β-barrel region of the protein (SI Text and Fig. S3 A-C).…”

“…PorB and other Gram-negative porins contain a ring of positively charged residues on the extracellular side of the protein. This evolutionarily conserved ring of positive charges may be important for guiding the directional insertion of this protein into the membrane, and is proposed to interact with the negatively charged lipopolysaccharides to stabilize the porin within the bacterial outer membrane (37,58). An electrostatic analysis of the TLR1/2 heterodimer reveals that both ectodomains, which mediate recognition, are predominantly negatively charged (Fig.…”

Porines bactériennes et sensibilité aux antibiotiques

“…La membrane externe est une bicouche asymétrique constituée du lipopolysaccharide (LPS) et de phospholipides, où s'insèrent de nombreuses protéines. Parmi elles, les porines sont des protéines transmembranaires formant des pores ou canaux protéiques permettant l'entrée de petits solutés hydrophiles (Figure 2 Figure 2) [4][5][6][7][8][9][10], et des analyses structure-fonction ont été réalisées.…”