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Structure of Thermotoga maritima Stationary Phase Survival Protein SurE : A Novel Acid Phosphatase
Background: The rpoS, nlpD, pcm, and surE genes are among many whose expression is induced during the stationary phase of bacterial growth. rpoS codes for the stationary-phase RNA polymerase σ subunit, and nlpD codes for a lipoprotein. The pcm gene product repairs damaged proteins by converting the...
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Published in: | Structure (London) 2001-11, Vol.9 (11), p.1095-1106 |
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Main Authors: | , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Background: The
rpoS, nlpD, pcm, and
surE genes are among many whose expression is induced during the stationary phase of bacterial growth.
rpoS codes for the stationary-phase RNA polymerase σ subunit, and
nlpD codes for a lipoprotein. The
pcm gene product repairs damaged proteins by converting the atypical isoaspartyl residues back to
L-aspartyls. The physiological and biochemical functions of
surE are unknown, but its importance in stress is supported by the duplication of the
surE gene in
E. coli subjected to high-temperature growth. The
pcm and
surE genes are highly conserved in bacteria, archaea, and plants.
Results: The structure of SurE from
Thermotoga maritima was determined at 2.0 Å. The SurE monomer is composed of two domains; a conserved N-terminal domain, a Rossman fold, and a C-terminal oligomerization domain, a new fold. Monomers form a dimer that assembles into a tetramer. Biochemical analysis suggests that SurE is an acid phosphatase, with an optimum pH of 5.5–6.2. The active site was identified in the N-terminal domain through analysis of conserved residues. Structure-based site-directed point mutations abolished phosphatase activity.
T. maritima SurE intra- and intersubunit salt bridges were identified that may explain the SurE thermostability.
Conclusions: The structure of SurE provided information about the protein's fold, oligomeric state, and active site. The protein possessed magnesium-dependent acid phosphatase activity, but the physiologically relevant substrate(s) remains to be identified. The importance of three of the assigned active site residues in catalysis was confirmed by site-directed mutagenesis. |
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ISSN: | 0969-2126 1878-4186 |
DOI: | 10.1016/S0969-2126(01)00675-X |