Abstract
Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55A resolution. The binary complex forms a characteristic "V" shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Acetyl Coenzyme A / chemistry*
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Acetyl Coenzyme A / metabolism
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Acetylation
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Acetyltransferases / chemistry*
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Acetyltransferases / metabolism
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Amino Acid Motifs
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Amino Acid Sequence
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Bacterial Proteins*
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Crystallization
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Crystallography, X-Ray
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Drosophila Proteins
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Histone Acetyltransferases
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Models, Molecular
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Molecular Sequence Data
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Phylogeny
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Protein Conformation
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Pseudomonas / enzymology*
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Recombinant Proteins / chemistry
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / metabolism
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Selenomethionine / chemistry
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Sequence Homology, Amino Acid
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beta-Lactams / metabolism*
Substances
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Bacterial Proteins
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Drosophila Proteins
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Recombinant Proteins
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Saccharomyces cerevisiae Proteins
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beta-Lactams
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Acetyl Coenzyme A
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Selenomethionine
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Acetyltransferases
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tabtoxin-resistance protein, Pseudomonas syringae
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GCN5 protein, Drosophila
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Histone Acetyltransferases