Specific Targeting of the Metallophosphoesterase YkuE to the Bacillus Cell Wall Requires the Twin-arginine Translocation System

Marcus Miethke,René van der Ploeg,Carmine G. Monteferrante,Jan Maarten van Dijl,Corinna Glasner

doi:10.1074/jbc.m112.378190

Marcus Miethke, René van der Ploeg + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m112.378190

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Abstract

The twin-arginine translocation (Tat) pathway is dedicated to the transport of fully folded proteins across the cytoplasmic membranes of many bacteria and the chloroplast thylakoidal membrane. Accordingly, Tat-dependently translocated proteins are known to be delivered to the periplasm of Gram-negative bacteria, the growth medium of Gram-positive bacteria, and the thylakoid lumen. Here, we present the first example of a protein, YkuE of Bacillus subtilis, that is specifically targeted by the Tat pathway to the cell wall of a Gram-positive bacterium. The cell wall binding of YkuE is facilitated by electrostatic interactions. Interestingly, under particular conditions, YkuE can also be targeted to the cell wall in a Tat-independent manner. The biological function of YkuE was so far unknown. Our present studies show that YkuE is a metal-dependent phosphoesterase that preferentially binds manganese and zinc.

Highlights

The Gram-positive bacterium Bacillus subtilis contains two twin-arginine (Tat) translocases, each secreting one known substrate protein
The localization of mature YkuE to the cell wall was strictly dependent on the presence of the TatAyCy translocase because this protein was not detectable in the cell wall fractions of the tatAyCy mutant and the total tat mutant, it was detectable in the cell wall fraction of the tatAdCd mutant
We show that the YkuE protein is a genuine substrate of the B. subtilis Tat pathway and that the TatAyCy translocase directs this protein to the cell wall

Summary

Introduction

The Gram-positive bacterium Bacillus subtilis contains two twin-arginine (Tat) translocases, each secreting one known substrate protein. Conclusion: YkuE is the third identified genuine Tat substrate in Bacillus. Significance: YkuE is the first protein found to be targeted to a Gram-positive bacterial cell wall via the Tat pathway. The twin-arginine translocation (Tat) pathway is dedicated to the transport of fully folded proteins across the cytoplasmic membranes of many bacteria and the chloroplast thylakoidal membrane. Tat-dependently translocated proteins are known to be delivered to the periplasm of Gram-negative bacteria, the growth medium of Gram-positive bacteria, and the thylakoid lumen. We present the first example of a protein, YkuE of Bacillus subtilis, that is targeted by the Tat pathway to the cell wall of a Gram-positive bacterium. Our present studies show that YkuE is a metal-dependent phosphoesterase that preferentially binds manganese and zinc

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