Nucleoside Triphosphate Diphosphohydrolase 1 Exhibits Enzymatic Activity toward Tenofovir Diphosphate. 2023

Herana Kamal Seneviratne
Department of Chemistry and Biochemistry, University of Maryland, Baltimore County and Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland hsenevi1@umbc.edu hsenevi1@jhmi.edu.

Tenofovir (TFV; prescribed as TFV disoproxil fumarate and TFV alafenamide prodrugs) is currently used for HIV prevention and treatment. TFV must be phosphorylated twice into TFV-diphosphate (TFV-DP) to become pharmacologically active. Previously, we reported heterogeneity in TFV-DP distribution in colorectal tissue (a putative site of HIV infection) sections collected from research participants receiving a TFV-containing enema. This observed heterogeneity is likely multifactorial. Of note, TFV-DP is structurally similar to ATP. It is known that nucleotidases such as nucleoside triphosphate diphosphohydrolases (NTPDases) dephosphorylate ATP. Thus, it was hypothesized that NTPDase-mediated dephosphorylation plays a role in regulating TFV-DP levels in colorectal tissue. To test this hypothesis, recombinant NTPDase proteins (NTPDase 1, 3, 4, 5, 6, and 8) were incubated, individually, with TFV-DP to determine their abilities to dephosphorylate TFV-DP in vitro. Following incubations, TFV-DP dephosphorylation was determined using both malachite green phosphate assays and ultrahigh-performance liquid chromatography tandem mass spectrometry. From these, NTPDase 1 exhibited the highest activity toward TFV-DP. Further, enzyme kinetic analysis revealed Michaelis-Menten kinetics for NTPDase 1-mediated TFV-DP dephosphorylation. Next, immunoblot analyses were conducted to confirm the expression of NTPDase 1 protein in human colorectal tissue. Liquid chromatography coupled to mass spectrometry proteomics analysis was used to measure the relative abundance of NTPDases in human colorectal tissue among healthy adult individuals (n = 4). These analyses confirmed the high abundance of NTPDase 1 in human colorectal tissue. Taken together, results suggest that NTPDase 1 may contribute to the regulation of TFV-DP levels. The above data provide important insights into the dephosphorylation of TFV-DP. SIGNIFICANCE STATEMENT: Nucleoside triphosphate diphosphohydrolases (NTPDases) that are involved in enzymatic ATP dephosphorylation may contribute to tenofovir-diphosphate (TFV-DP) dephosphorylation, leading to its inactivation. In this study, the NTPDases responsible for TFV-DP dephosphorylation in vitro and their expression in human colorectal tissue were investigated. Through this work, it was demonstrated that NTPDase 1 has the highest activity toward TFV-DP dephosphorylation, and it was abundant in human colorectal tissue. Importantly, these studies will increase our understanding of TFV-DP disposition.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D009705 Nucleosides Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed) Nucleoside,Nucleoside Analog,Nucleoside Analogs,Analog, Nucleoside,Analogs, Nucleoside
D009711 Nucleotides The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed) Nucleotide
D011756 Diphosphates Inorganic salts of phosphoric acid that contain two phosphate groups. Diphosphate,Pyrophosphate Analog,Pyrophosphates,Pyrophosphate Analogs,Analog, Pyrophosphate
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000068698 Tenofovir An adenine analog REVERSE TRANSCRIPTASE INHIBITOR with antiviral activity against HIV-1 and HEPATITIS B. It is used to treat HIV INFECTIONS and CHRONIC HEPATITIS B, in combination with other ANTIVIRAL AGENTS, due to the emergence of ANTIVIRAL DRUG RESISTANCE when it is used alone. (R)-9-(2-phosphonylmethoxypropyl)adenine,9-(2-Phosphonomethoxypropyl)adenine,9-(2-Phosphonylmethoxypropyl)adenine,9-(2-Phosphonylmethoxypropyl)adenine, (+-)-isomer,9-(2-Phosphonylmethoxypropyl)adenine, (R)-isomer - T357098,9-(2-Phosphonylmethoxypropyl)adenine, (S)-isomer,9-PMPA (tenofovir),Tenofovir Disoproxil,Tenofovir Disoproxil Fumarate,Viread,Disoproxil Fumarate, Tenofovir,Disoproxil, Tenofovir,Fumarate, Tenofovir Disoproxil
D000255 Adenosine Triphosphate An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter. ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D015179 Colorectal Neoplasms Tumors or cancer of the COLON or the RECTUM or both. Risk factors for colorectal cancer include chronic ULCERATIVE COLITIS; FAMILIAL POLYPOSIS COLI; exposure to ASBESTOS; and irradiation of the CERVIX UTERI. Colorectal Cancer,Colorectal Carcinoma,Colorectal Tumors,Neoplasms, Colorectal,Cancer, Colorectal,Cancers, Colorectal,Carcinoma, Colorectal,Carcinomas, Colorectal,Colorectal Cancers,Colorectal Carcinomas,Colorectal Neoplasm,Colorectal Tumor,Neoplasm, Colorectal,Tumor, Colorectal,Tumors, Colorectal
D015658 HIV Infections Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS). HTLV-III Infections,HTLV-III-LAV Infections,T-Lymphotropic Virus Type III Infections, Human,HIV Coinfection,Coinfection, HIV,Coinfections, HIV,HIV Coinfections,HIV Infection,HTLV III Infections,HTLV III LAV Infections,HTLV-III Infection,HTLV-III-LAV Infection,Infection, HIV,Infection, HTLV-III,Infection, HTLV-III-LAV,Infections, HIV,Infections, HTLV-III,Infections, HTLV-III-LAV,T Lymphotropic Virus Type III Infections, Human

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