YcdB from Escherichia coli reveals a novel class of Tat-dependently translocated hemoproteins

verfasst von

Alexander Sturm, Angelika Schierhorn, Ute Lindenstrauss, Hauke Lilie, Thomas Brüser

Abstract

The Tat (twin-arginine translocation) system of Escherichia coli serves to translocate folded proteins across the cytoplasmic membrane. The reasons established so far for the Tat dependence are cytoplasmic cofactor assembly and/or heterodimerization of the respective proteins. We were interested in the reasons for the Tat dependence of novel Tat substrates and focused on two uncharacterized proteins, YcdO and YcdB. Both proteins contain predicted Tat signal sequences. However, we found that only YcdB was indeed Tat-dependently translocated, whereas YcdO was equally well translocated in a Tat-deficient strain. YcdB is a dimeric protein and contains a heme cofactor that was identified to be a high-spin Fe^III-protoporphyrin IX complex. In contrast to all other periplasmic hemoproteins analyzed so far, heme was assembled into YcdB in the cytoplasm, suggesting that heme assembly could take place prior to translocation. The function of YcdB in the periplasm may be related to a detoxification reaction under specific conditions because YcdB had peroxidase activity at acidic pH, which coincides well with the known acid-induced expression of the gene. The data demonstrate the existence of a class of heme-containing Tat substrates, the first member of which is YcdB.

Organisationseinheit(en)

Institut für Mikrobiologie

Externe Organisation(en)

Martin-Luther-Universität Halle-Wittenberg
Max-Planck-Forschungsstelle für Enzymologie der Proteinfaltung

Typ

Artikel

Journal

Journal of Biological Chemistry

Band

281

Seiten

13972-13978

Anzahl der Seiten

7

ISSN

0021-9258

Publikationsdatum

19.05.2006

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Biochemie, Molekularbiologie, Zellbiologie

Elektronische Version(en)

https://doi.org/10.1074/jbc.M511891200 (Zugang: Offen)