An immunoblot assay reveals that bacteriophage T4 thymidylate synthase and dihydrofolate reductase are not virion proteins.
Numerous reports describe the phage T4 enzymes thymidylate synthase and dihydrofolate reductase as structural components of the baseplate. However, Y. Wang and C. K. Mathews (J. Virol. 63:4736-4743, 1989) reported that antisera against the respective recombinant enzymes failed to neutralize phage infectivity, in contrast to previous results. Moreover, a deletion mutant lacking the genes for these two enzymes adsorbed normally to host cells. Since these findings tended to undermine the idea of the two enzymes as structural proteins, we developed a quantitative immunoblot assay to resolve the issue directly. Our results show that both enzymes are present only as minor contaminants (< 0.05 copy per phage) and as such cannot be bona fide structural proteins.
Chen
X
X
Department of Biology, University of New Brunswick, Fredericton, Canada.
Mathews
C K
CK
Wheeler
L J
LJ
Maley
G
G
Maley
F
F
Coombs
D H
DH
D017122:Bacteriophage T4 / Q000201:enzymology*; D015153:Blotting, Western; D002460:Cell Line; D007106:Immune Sera; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism*; D013940:Thymidylate Synthase / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*; D014771:Virion / Q000201:enzymology*
D007106:Immune Sera; D014764:Viral Proteins; D013762:Tetrahydrofolate Dehydrogenase; D013940:Thymidylate Synthase