Journal of Biological Chemistry
Volume 280, Issue 31, 5 August 2005, Pages 28281-28289
Journal home page for Journal of Biological Chemistry

Membrane Transport, Structure, Function, and Biogenesis
The Evolutionarily Related β-Barrel Polypeptide Transporters from Pisum sativum and Nostoc PCC7120 Contain Two Distinct Functional Domains*

https://doi.org/10.1074/jbc.M503035200Get rights and content
Under a Creative Commons license
open access

Several β-barrel-type channels are involved in the translocation or assembly of outer membrane proteins of bacteria or endosymbiotically derived organelles. Here we analyzed the functional units of the β-barrel polypeptide transporter Toc75 (translocon in outer envelope of chloroplasts) of the outer envelope of chloroplasts and of a protein, alr2269, from Nostoc PCC7120 with homology to Toc75, both proteins having a similar domain organization. We demonstrated that the N-terminal region functions as a recognition and complex assembly unit, whereas the C terminus forms the β-barrel-type pore. The pore region is, in turn, modulated by the N terminus of the proteins. The protein from Nostoc PCC7120, which shares a common ancestor with Toc75, is able to recognize precursor proteins destined for chloroplasts. In contrast, the recognition of peripheral translocon subunits by Toc75 is a novel feature acquired through evolution.

Cited by (0)

*

This work was supported by grants from the Deutsche Forschungsgemeinschaft, Fonds der Chemischen Industrie, and the Volkswagenstiftung (to E. S.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains a supplemental table and a figure.