Immucillin-H, a purine nucleoside phosphorylase transition state analog, causes non-lethal attenuation of growth in Staphylococcus aureus
Year: 2013
Type: article
Abstract: Purine nucleoside phosphorylase (PNP; EC: 2.4.2.1) is a key enzyme involved in the purine salvage pathway.A recent bioinformatic study by Yadav, P. K. et al. (Bioinformation 2012, 8(14), 664-672) reports PNP as an essential enzyme and potential drug target in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA).We conducted an analysis using the methodology outlined by the authors, but were unable to identify PNP as an essential gene product in CA-MRSA.In addition, the treatment of Staphylococcus aureus cultures with immucillin-H, a powerful inhibitor of PNP, resulted in the non-lethal attenuation of growth, suggesting that PNP activity is not essential for cell viability.Background: A recent study by Yadav, P. K. et al. used a bioinformatic approach to identify potential drug targets in communityacquired methicillin-resistant Staphylococcus aureus (CA-MRSA) [1].In this work, the BLASTp program was used to search metabolically relevant gene products in CA-MRSA against the proteome of Homo sapiens.A collection of non-homologous gene products was generated and further refined by the identification of essential genes in the DEG 6.8 database [2].Using this approach, Yadav, P. K. et al. identified purine nucleoside phosphorylase (PNP; EC: 2.4.2.1) as an essential enzyme and potential drug target in CA-MRSA [1].PNP catalyzes the reversible phosphorolysis of 6-oxypurine ribonucleosides to the corresponding purine nucleobases and ribose 1-phosphate (Figure 1A) [3].PNP is a key enzyme involved in the purine salvage pathway and is essential in humans for the formation of uric acid [3].Our laboratory has previously investigated the catalytic mechanism and transition state structure of PNP (Figure 1B) using kinetic isotope effect (KIE) analysis [4, 5].Transition state analysis was used in the design of transition state analogs for PNP, including immucillin-H (ImmH; Figure 1C), which is a potent inhibitor of bovine PNP (Ki = 23 pM) [6], human PNP (Ki = 58 pM) [5], and bacterial PNP (Ki = 28 pM; M. tuberculosis) [7].ImmH is currently in clinical trials for the treatment of leukemia [8, 9].Yadav, P. K. et al. used non-homology between gene products in CA-MRSA and Homo sapiens as a key parameter to select potential drug targets.We were interested to find the authors identified PNP as a candidate despite the presence of PNP homologs in both CA-MRSA (NCBI Gene ID: 1004861) and Homo sapiens (NCBI Gene ID: 4860).An independent analysis of the DEG 6.8 database following the methodology outlined by Yadav, P. K. et al. was unable to identify PNP as an essential enzyme in CA-MRSA.Moreover, we conducted a series of cellular growth assays using a laboratory strain of Staphylococcus aureus and ImmH, a potent inhibitor of PNP developed by our laboratory.These assays indicate that ImmH causes non-lethal attenuation of growth in Staphylococcus aureus, suggesting that PNP activity is not essential to the organism.
Source: Bioinformation
Authors: Christopher F Stratton, Vern L Schramm
Institutions: Albert Einstein College of Medicine, Yeshiva University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
OpenAlex ID: W2144308504