This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.088781v1 91/9/3242    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zakharian, E. Articles by Reusch, R. N. Search for Related Content PubMed PubMed Citation Articles by Zakharian, E. Articles by Reusch, R. N.

Pore Characteristics of Nontypeable Haemophilus influenzae Outer Membrane Protein P5 in Planar Lipid Bilayers

Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824

Correspondence: Address reprint requests to Rosetta N. Reusch, Tel.: 517-355-6463; Fax: 517-353-8957; E-mail: rnreusch{at}msu.edu.

The structure of outer membrane protein P5 of NTHi, a homolog of Escherichia coli OmpA, was investigated by observing its pore characteristics in planar lipid bilayers. Recombinant NTHi P5 was overexpressed in E. coli and purified using ionic detergent, LDS-P5, or nonionic detergent, OG-P5. LDS-P5 and OG-P5 could not be distinguished by their migration on SDS-PAGE gels; however, when incorporated into planar bilayers of DPhPC between symmetric aqueous solutions of 1 M KCl at 22°C, LDS-P5 formed narrow pores (58 ± 6 pS) with low open probability, whereas OG-P5 formed large pores (1.1 ± 0.1 nS) with high open probability (0.99). LDS-P5 narrow pores were gradually and irreversibly transformed into large pores, indistinguishable from those formed by OG-P5, at temperatures 40°C; the process took 4–6 h at 40°C or 35–45 min at 42°C. Large pores were stable to changes in temperatures; however, large pores were rapidly converted to narrow pores when exposed to LDS at room temperatures, indicating acute sensitivity of this conformer to ionic detergent. These studies suggest that narrow pores are partially denatured forms and support the premise that the native conformation of NTHi P5 is that of a large monomeric pore.

This article has been cited by other articles:

				E. Zakharian and R. N. Reusch Haemophilus influenzae Outer Membrane Protein P5 Is Associated with Inorganic Polyphosphate and Polyhydroxybutyrate Biophys. J., January 15, 2007; 92(2): 588 - 593. [Abstract] [Full Text] [PDF]