Antibody-nucleic acid complexes. Immunospecific recognition of 7-methylguanine- and N6-methyladenine-containing 5'-terminal oligonucleotides of mRNA.

Abstract

Antibodies specific for 'I-methylguanosine (m'G) and for N6-methyladenosine (meA) were immobilized on Sepharose (anti-m'G and -m'A/Sepharose) and the resulting immunoadsorbents were assessed for their ability to retain hapten-containing V-terminal oligonucleotide structures (caps) present in nuclease-digested, late adenovirus 2 mRNA preparations, Fe. ?-methylguanine (7meGua) and W-methyladenine (6meAde).Results obtained with ribonuclease TZ digests of mRNA (previously labeled with [methyC-3H]methionine) indicated that the anti-m'G/Sepharose adsorbent immunospecifically retained 7meGua-containing caps of adenovirus mRNA.A subclass of V-terminal caps possessing 6meAde were isolated by incubating an identical mRNA digest with anti-m'A/Sepharose adsorbent.Characterization of these retained oligonucleotides with respect to their (a) elution from DEAELSephacel adsorbent and (b) composition of [methyr-3HJmethylated bases revealed that these immunoadsorbents quantitatively and exclusively retained the 'ImeGuaand GmeAde-containing V-terminal cap structures of late adenovirus 2 mRNA.These findings are in agreement with previously characterized V-terminal oligonucleotides of mRNA preparations which indicate structures of the type m7G(5')ppp(5')NmpNp and m7G(5')ppp(5')N"'pN"pNp, where N"' represents 2'-Omethylnucleosides.As revealed by anti-m'A/Sepharose adsorption studies, approximately 20% of the viral mRNA caps possessed GmeAde, tentatively identified as N8,2'-O-dimethyladenosine (m6Am).