Premium
Secretome analysis of A nabaena sp. PCC 7120 and the involvement of the TolC ‐homologue HgdD in protein secretion
Author(s) -
Hahn Alexander,
Stevanovic Mara,
Brouwer Eva,
Bublak Daniela,
Tripp Joanna,
Schorge Tobias,
Karas Michael,
Schleiff Enrico
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12516
Subject(s) - secretion , periplasmic space , biology , secretory protein , mutant , microbiology and biotechnology , signal peptide , extracellular , bacterial outer membrane , secretory pathway , biochemistry , peptide sequence , escherichia coli , gene , endoplasmic reticulum , golgi apparatus
Summary Secretion of proteins is a central strategy of bacteria to influence and respond to their environment. Until now, there has been very few discoveries regarding the cyanobacterial secrotome or the secretion machineries involved. For a mutant of the outer membrane channel TolC ‐homologue HgdD of A nabaena sp. PCC 7120, a filamentous and heterocyst‐forming cyanobacterium, an altered secretome profile was reported. To define the role of HgdD in protein secretion, we have developed a method to isolate extracellular proteins of A nabaena sp. PCC 7120 wild type and an hgdD loss‐of‐function mutant. We identified 51 proteins of which the majority is predicted to have an extracellular secretion signal, while few seem to be localized in the periplasmic space. Eight proteins were exclusively identified in the secretome of wild‐type cells, which coincides with the distribution of type I secretion signal. We selected three candidates and generated hemagglutinin‐tagged fusion proteins which could be exclusively detected in the extracellular protein fraction. However, these proteins are not secreted in the hgdD ‐mutant background, where they are rapidly degraded. This confirms a direct function of HgdD in protein secretion and points to the existence of a quality control mechanism at least for proteins secreted in an HgdD ‐dependent pathway.