2,6-diaminopurine (2,6-DAP, also known as 2-aminoadenine, standard IUPAC symbol n2A[1]: N4.1, N4.4 ) is a compound once used in the treatment of leukemia.[2] It is found instead of adenine (A) in the genetic material of some bacteriophage viruses,[3]
In August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting 2,6-diaminopurine and related organic molecules, including the DNA and RNA components adenine and guanine, may have been formed extraterrestrially in outer space.[4][5][6]
In virology it is referred to as the "Z" base.[7] However, "Z" refers instead to 6-amino-5-nitropyridin-2-one in the Artificially Expanded Genetic Information System (AEGIS), so context is required to differentiate.[8] AEGIS refers to this base as "AminoA" instead.[9]
It has also been called the "D" base,[10][11] but the more common interpretation of "D" is dihydrouridine.[12]
In viruses
DiampurineT DNA base pair
In cyanophage S-2L (Siphoviridae), diaminopurine is used instead of adenine (host evasion).[13] Diaminopurine base (Z) pairs perfectly with thymine (T) as it is identical to adenine (A) but has an amine group at position 2 forming 3 intermolecular hydrogen bonds, eliminating the major difference between the two types of basepairs (weak:A-T and strong:C-G). This improved stability affects protein-binding interactions that rely on those differences.
Four papers published April 2021 further describes the use and production of the Z-base. It is now known that:[14]
The S-2L phage avoids incorporating A bases in the genome by hydrolyzing dATP (DatZ enzyme);[15]
The Z base is produced by a pathway involving DUF550 (MazZ) and PurZ in S-2L and Vibrio phage PhiVC8;[7]
The Z base is quite widespread in both Siphoviridae and Podoviridae, based on the occurrence of the said gene cluster.[17]
In August 2021, it was shown that DatZ, MazZ and PurZ are sufficient to replace some occurrence of A by Z in the bacterial genome of E. coli; expression of this system is toxic to the cell. The structures of MazZ (subtype 2) and PurZ are also determined, showing a possible link between PurZ and archaeal versions of PurA.[18]
Biosynthesis
2-aminoadenine is produced in two steps. The enzyme MazZ (homologous to MazG, EC 3.6.1.8) first performs:[18]
dGTP + H2O = dGMP + diphosphate
The enzyme PurZ (homologous to PurA, EC 6.3.4.4) then performs:[7]
The resulting dSMP is processed by host enzymes analogously to adenylosuccinate to produce dZTP.
In cellular life
This article is missing information about results of the altered H-bond strength in DNA and RNA. Please expand the article to include this information. Further details may exist on the talk page.(October 2021)
2,6-DAP was used to treat leukemia since as early as 1951.[19] It is known to arrest progression of cell cycle in mouse leukemia cells by 1989.[20] Cancer cells are known to become resistant to DAP by losing their adenine phosphoribosyltransferase (APRT) function,[21] a process shared with E. coli.[22]
DAP derivatives are in vitro antivirals useful against pseudorabies virus, a economically important livestock disease.[23] This base, in its free form, is able to correct UGA nonsense mutations by encouraging translational readthrough, through the inhibition of FTSJ1.[24]
↑Benner, SA; Hutter, D; Sismour, AM (1 September 2003). "Synthetic biology with artificially expanded genetic information systems. From personalized medicine to extraterrestrial life.". Nucleic Acids Research. Supplement3 (3): 125–6. doi:10.1093/nass/3.1.125. PMID14510412.
↑IUPAC-IUB Commission on Biochemical Nomenclature (1970). "Abbreviations and symbols for nucleic acids, polynucleotides, and their constituents". Biochemistry9 (20): 4022–4027. doi:10.1021/bi00822a023.
↑Kirnos, MD; Khudyakov, IY; Alexandrushkina, NI; Vanyushin, BF (November 1977). "2-aminoadenine is an adenine substituting for a base in S-2L cyanophage DNA". Nature270 (5635): 369–70. doi:10.1038/270369a0. PMID413053. Bibcode: 1977Natur.270..369K.
↑Burchenal, JH; Karnofsky, DA; Kingsley-Pillers, EM; Southam, CM; Myers, WP; Escher, GC; Craver, LF; Dargeon, HW et al. (May 1951). "The effects of the folic acid antagonists and 2,6-diaminopurine on neoplastic disease, with special reference to acute leukemia". Cancer4 (3): 549–69. doi:10.1002/1097-0142(195105)4:3<549::aid-cncr2820040308>3.0.co;2-j. PMID14839611.
↑Weckbecker, G; Cory, JG (1989). "Metabolic activation of 2,6-diaminopurine and 2,6-diaminopurine-2'-deoxyriboside to antitumor agents.". Advances in Enzyme Regulation28: 125–44. doi:10.1016/0065-2571(89)90068-x. PMID2624171.
↑Kocharian, ShM; Chukanova, TI; Sukhodolets, VV (1977). "[Mutations of resistance to 2,6-diaminopurine and 6-methylpurine that affect adenine phosphoribosyltransferase in Escherichia coli K-12].". Genetika13 (10): 1821–30. PMID348574.
↑Zouharova, D; Lipenska, I; Fojtikova, M; Kulich, P; Neca, J; Slany, M; Kovarcik, K; Turanek-Knotigova, P et al. (29 February 2016). "Antiviral activities of 2,6-diaminopurine-based acyclic nucleoside phosphonates against herpesviruses: In vitro study results with pseudorabies virus (PrV, SuHV-1).". Veterinary Microbiology184: 84–93. doi:10.1016/j.vetmic.2016.01.010. PMID26854349.