Novel ATP-driven Pathway of Glycolipid Export Involving TolC Protein

Abstract

Background:The ABC exporter DevBCA and the outer membrane protein TolC are necessary for maturation of heterocysts in filamentous cyanobacteria. Results: DevBCA-TolC form an ATP-driven efflux pump and export heterocyst-specific glycolipids. Conclusion: DevBCA-TolC provide a novel pathway for glycolipid export. Significance: Mechanistic details of efflux pumps/ABC exporters are important for understanding various bacterial processes such as cell differentiation, acclimatization processes, or drug resistance.

The TolC-like Protein HgdD of the Cyanobacterium Anabaena sp. PCC 7120 Is Involved in Secondary Metabolite Export and Antibiotic Resistance

“…This underlines the importance of this protein previously found to modulate the protein secretion pattern (5) and the lipid export activity (20) as well.…”

“…PCC 7120 (referred to hereafter as Anabaena sp.) has been identified by proteomic analysis (18,19), and its relation to the TolC family was confirmed by homology modeling and analysis of the corresponding mutant (5,7,20). Anabaena sp.…”

“…genome (5). Including our results, four distinct functions have been assigned to it: protein secretion (5) and glycolipid (20), siderophore (7), and antibiotic export (Fig. 7).…”

The Outer Membrane TolC-like Channel HgdD Is Part of Tripartite Resistance-Nodulation-Cell Division (RND) Efflux Systems Conferring Multiple-drug Resistance in the Cyanobacterium Anabaena sp. PCC7120

“…The mutant of the TolC-like gene hgdD (heterocyst glycolipid deposition protein D; alr2887) is impaired in heterocyst development. Based on the comparable phenotype of mutants of hgdD (9) and of the ABC exporter DevBCA (alr3170 -alr3172) (20), it was proposed that DevBCA-HgdD is responsible for heterocyst glycolipid (HGL) secretion (9,17). Furthermore, the mutant of hgdD is impaired in secretion of hydroxamate-type siderophores (7), and initial results suggest that HgdD might also be involved in protein secretion (9).…”

“…PCC 7120 (hereafter referred to as Anabaena sp.) has been identified experimentally (5,7,9,17). Anabaena sp.…”