Poly(U) RNA-templated synthesis of AppA.
Simple nucleotide templating activities are of interest as potential primordial reactions. Here we describe the acceleration of 5'-5' AppA synthesis by 3'-5' poly(U) under normal solution conditions. This reaction is apparently templated via complementary U:A base-pairing, despite the involvement of two different RNA backbones, because poly(U), unlike other polymers, significantly stimulates AppA synthesis. These interactions occur in moderate (K(+)) and (Mg(2+)) and are temperature sensitive, being more efficient at 10°C than at 4°C, but absent at 20°C. The reaction is only slightly pH sensitive, despite potentially relevant substrate pKa's. Kinetic data explicitly support production of AppA by interaction of stacked 2MeImpA and pA nucleotides paired with a single molecule of U template. At a lower rate, AppA can also be produced by a chemical reaction between 2MeImpA and pA, without participation of poly(U). Molecular modeling suggests that 5'-5' joining between stacked or concurrently paired A's can occur without major departures from normal U-A helical coordinates. So, coenzyme-like 5'-5' purine dinucleotides might be readily synthesized from 3'-5' RNAs with complementary sequences.
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA.
Deepa
D
Puthenvedu
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA Department of Biotechnology and Molecular Biology, University of Opole, 45-032 Opole, Poland.
Teresa
T
Janas
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA.
Irene
I
Majerfeld
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA.
Mali
M
Illangasekare
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA.
Michael
M
Yarus
D015226:Dinucleoside Phosphates / Q000096:biosynthesis*; D011072:Poly U / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*
D015226:Dinucleoside Phosphates; C012276:diadenosine pyrophosphate; D011072:Poly U; D012313:RNA
coenzyme; cofactor; reproduction; ribodinucleotide; template