9cr5

Publication Abstract from PubMed

Polyamines within the cell are tightly regulated by spermidine/spermine N-acetyltransferase (SSAT) enzymes. While several SSATs have been investigated in different bacterial species, there is still a significant gap in knowledge about which proteins are functional SSATs in many organisms. For example, while it is known that Pseudomonas aeruginosa synthesizes the polyamine spermidine, the SSAT that acetylates this molecule and its importance in regulating intracellular polyamines remains unknown. We previously identified a candidate Gcn5-related N-acetyltransferase (GNAT) protein from P. aeruginosa (PA2271) that could fulfill this role since it acetylates spermidine, but no further studies were conducted. Here, we explored the structure/function relationship of the PA2271 protein by determining its X-ray crystal structure and performing enzyme kinetics assays. We also identified active site residues that are essential for catalysis and substrate binding. As the study progressed, we encountered results that led us to explore the importance of four cysteine residues on enzyme activity and disulfide bond formation or modification of cysteine residues. We found these cysteine residues in PA2271 are important for protein solubility and activity, and there is an interrelationship between cysteine residues that contribute to these effects. Furthermore, we also found disulfide bonds could form between C(121) and C(165) and speculate that these residues may contribute to redox regulation of PA2271 protein activity.

Structural, functional, and regulatory evaluation of a cysteine post-translationally modified Gcn5-related N-acetyltransferase.,Uychoco P, Majorek KA, Ives AN, Le VTB, Caro De Silva PL, Paurus VL, Attah IK, Lipton MS, Minor W, Kuhn ML Biochem Biophys Res Commun. 2025 Feb 8;748:151299. doi: , 10.1016/j.bbrc.2025.151299. Epub 2025 Jan 11. PMID:39826527^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.