Structural and Functional Evidence for Bacillus subtilis PaiA as a Novel N1-Spermidine/Spermine Acetyltransferase

Abstract

Bacillus subtilis PaiA has been implicated in the negative control of sporulation as well as production of degradative enzymes. PaiA shares recognizable sequence homology with N-acetyltransferases, including those that can acetylate spermidine/spermine substrates. We have determined the crystal structure of PaiA in complex with CoA at 1.9 Å resolution and found that PaiA is a member of the N-acetyltransferase superfamily of enzymes. Unexpectedly, we observed the binding of an oxidized CoA dimer in the active site of PaiA, and the structural information suggests the substrates of the enzyme could be linear, positively charged compounds. Our biochemical characterization is also consistent with this possibility, since purified PaiA possesses N 1 -acetyltransferase activity toward polyamine substrates including spermidine and spermine. Further, conditional overexpression of PaiA in bacteria results in increased acetylation of endogenous spermidine pools. Thus, our structural and biochemical analyses indicate that PaiA is a novel N-acetyltransferase capable of acetylating both spermidine and spermine. In this way, the pai operon may function in regulating intracellular polyamine concentrations and/or binding capabilities. In addition to preventing toxicity due to polyamine excess, this function may also serve to regulate expression of certain bacterial gene products such as those involved in sporulation.In Bacillus subtilis, the pai operon is involved in negative control of sporulation as well as the production of extracellular and cell-associated proteases and other enzymes such as ␣-amylase and alkaline phosphatase (1). The pai operon contains two genes, paiA and paiB, encoding proteins of 172 (PaiA) and 207 (PaiB) amino acid residues, respectively.

Bacterial degradation of spermine and expression of spermidine/spermine acetyltransferase in <i>Bacillus subtilis</i> (natto) under liquid cultivation

“…We observed that Spm degradation occurred faster than Spd degradation, supporting previous studies suggesting a reduction in Spm during the natto fermentation process (Kobayashi et al, 2016(Kobayashi et al, , 2017. Spm has been reported to be the preferred substrate for SSAT (Forouhar et al, 2005;Woolridge et al, 1999). From these data, nutrient conditions appear to influence polyamine degradation by B. subtilis (natto).…”

“…and PaiA (Forouhar et al, 2005), have been reported from B. subtilis 168 to be components of a putative spermidine/spermine acetyltransferase (SSAT) that could initiate polyamine degradation via acetylation. The genes encoding SSAT (bltD and paiA) are not essential for B. subtilis 168 according to BSORF Bacillus subtilis genome database (http://bacillus.genome.jp/).…”

Local and Global Regulators Linking Anaerobiosis tocupAFimbrial Gene Expression inPseudomonas aeruginosa

“…Although acetylases belonging to the GNAT family play important roles in regulating gene expression in eukaryotes (22,33), there are few examples in which acetylases are known to influence gene expression in prokaryotes (10,41). Perhaps CgrB acetylates either CgrA or CgrC to promote its activity.…”

Structures of wild-type and mutant human spermidine/spermine N 1 -acetyltransferase, a potential therapeutic drug target

“…The structure of Bacillus subtilis PaiA protein has recently been determined, and the protein was found to belong to the GNAT family and to have polyamine N 1 -acetyltransferase activity (30). Amino acid sequences of PaiA and nine bacterial proteins of related sequence show little resemblance to SSAT-like proteins by BLAST comparisons, but a sequence and structure alignment of SSAT and PaiA is given in Fig.…”