Methionine sulfoxide reductases protect Ffh from oxidative damages in Escherichia coli.
In proteins, methionine residues are primary targets for oxidation. Methionine oxidation is reversed by methionine sulfoxide reductases A and B, a class of highly conserved enzymes. Ffh protein, a component of the ubiquitous signal recognition particle, contains a methionine-rich domain, interacting with a small 4.5S RNA. In vitro analyses reported here show that: (i) oxidized Ffh is unable to bind 4.5S RNA, (ii) oxidized Ffh contains methionine sulfoxide residues, (iii) oxidized Ffh is a substrate for MsrA and MsrB enzymes; and (iv) MsrA/B repairing activities allow oxidized Ffh to recover 4.5S RNA-binding abilities. In vivo analyses reveal that: (i) Ffh synthesized in the msrA msrB mutant contains methionine sulfoxide residues and is unstable, (ii) msrA msrB mutant requires high levels of Ffh synthesis for growth and (iii) msrA msrB mutation leads to defects in Ffh-dependent targeting of MalF. We conclude that MsrA and MsrB are required to repair Ffh oxidized by reactive oxygen species produced by aerobic metabolism, establishing an as-yet undescribed link between protein targeting and oxidation.
Ezraty
Benjamin
B
Laboratoire de Chimie Bactérienne, Institut Fédératif de Recherche Biologie Structurale et Microbiologie, Centre National de la Recherche Scientifique, Marseille Cedex, France.
Grimaud
Régis
R
El Hassouni
Mohammed
M
Moinier
Daniéle
D
Barras
Frédéric
F
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D018271:Signal Recognition Particle / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D008565:Membrane Proteins; D018271:Signal Recognition Particle; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase