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The iron-regulated vacuolar Legionella pneumophila MavN protein is a transition-metal transporter.

Abstract：

:Legionella pneumophila causes a potentially fatal form of pneumonia by replicating within macrophages in the Legionella-containing vacuole (LCV). Bacterial survival and proliferation within the LCV rely on hundreds of secreted effector proteins comprising high functional redundancy. The vacuolar membrane-localized MavN, hypothesized to support iron transport, is unique among effectors because loss-of-function mutations result in severe intracellular growth defects. We show here an iron starvation response by L. pneumophila after infection of macrophages that was prematurely induced in the absence of MavN, consistent with MavN granting access to limiting cellular iron stores. MavN cysteine accessibilities to a membrane-impermeant label were determined during macrophage infections, revealing a topological pattern supporting multipass membrane transporter models. Mutations to several highly conserved residues that can take part in metal recognition and transport resulted in defective intracellular growth. Purified MavN and mutant derivatives were directly tested for transporter activity after heterologous purification and liposome reconstitution. Proteoliposomes harboring MavN exhibited robust transport of Fe2+, with the severity of defect of most mutants closely mimicking the magnitude of defects during intracellular growth. Surprisingly, MavN was equivalently proficient at transporting Fe2+, Mn2+, Co2+, or Zn2+ Consequently, flooding infected cells with either Mn2+ or Zn2+ allowed collaboration with iron to enhance intracellular growth of L. pneumophila ΔmavN strains, indicating a clear role for MavN in transporting each of these ions. These findings reveal that MavN is a transition-metal-ion transporter that plays a critical role in response to iron limitation during Legionella infection.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Christenson ET,Isaac DT,Yoshida K,Lipo E,Kim JS,Ghirlando R,Isberg RR,Banerjee A

doi

10.1073/pnas.1902806116

subject

Has Abstract

pub_date

2019-09-03 00:00:00

pages

17775-17785

issue

eissn

0027-8424

issn

1091-6490

pii

1902806116

journal_volume

116

pub_type

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The iron-regulated vacuolar Legionella pneumophila MavN protein is a transition-metal transporter.