Enzymatic and structural characterization of rTSγ provides insights into the function of rTSβ.
In humans, the gene encoding a reverse thymidylate synthase (rTS) is transcribed in the reverse direction of the gene encoding thymidylate synthase (TS) that is involved in DNA biosynthesis. Three isoforms are found: α, β, and γ, with the transcript of the α-isoform overlapping with that of TS. rTSβ has been of interest since the discovery of its overexpression in methotrexate and 5-fluorouracil resistant cell lines. Despite more than 20 years of study, none of the rTS isoforms have been biochemically or structurally characterized. In this study, we identified rTSγ as an l-fuconate dehydratase and determined its high-resolution crystal structure. Our data provide an explanation for the observed difference in enzymatic activities between rTSβ and rTSγ, enabling more informed proposals for the possible function of rTSβ in chemotherapeutic resistance.
Departments of Biochemistry and Chemistry, Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Daniel J
DJ
Wichelecki
D Sean
DS
Froese
Jolanta
J
Kopec
Joao R C
JR
Muniz
Wyatt W
WW
Yue
John A
JA
Gerlt
D018360:Crystallography, X-Ray; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008727:Methotrexate / Q000494:pharmacology; D008958:Models, Molecular; D011487:Protein Conformation
D007527:Isoenzymes; D006836:Hydro-Lyases; C002930:L-fuconate dehydratase; D005472:Fluorouracil; D008727:Methotrexate