TY - JOUR
T1 - Primary structure of the gene encoding the bifunctional dihydrofolate reductase-thymidylate synthase of Leishmania major
AU - Beverley, S. M.
AU - Ellenberger, T. E.
AU - Cordingley, J. S.
PY - 1986
Y1 - 1986
N2 - We have determined the nucleotide sequence of the dihydrofolate reductase-thymidylate synthetase (DHFR-TS) gene of the protozoan parasite Leishmania major (dihydrofolate reductase, EC 1.5.1.3 and thymidylate synthase, EC 2.1.1.45). The DHFR-TS protein is encoded by a single 1560-base-pair open reading frame within genomic DNA, in contrast to vertebrate DHFRs or mouse and phage T4 TSs, which contain intervening sequences. Comparisons of the DHFR-TS sequence with DHFR and TS sequences of other organisms indicate that (i) the order of enzymatic activities within the bifunctional polypeptide chain is DHFR followed by TS, (ii) the Leishmania bifunctional DHFR-TS evolved independently and not through a phage T4-related intermediate, and (iii) the rate of evolution of both the DHFR and TS domains has not detectably changed despite the acquisition of new functional properties by the bifunctional enzyme. The Leishmania gene is 86% G + C in the third codon position, in contrast to genes of the parasite Plasmodium falciparum, which exhibit an opposite bias toward A + T. The DHFR-TS locus is encoded within a region of DNA amplified in methotrexate-resistant lines, as previously proposed.
AB - We have determined the nucleotide sequence of the dihydrofolate reductase-thymidylate synthetase (DHFR-TS) gene of the protozoan parasite Leishmania major (dihydrofolate reductase, EC 1.5.1.3 and thymidylate synthase, EC 2.1.1.45). The DHFR-TS protein is encoded by a single 1560-base-pair open reading frame within genomic DNA, in contrast to vertebrate DHFRs or mouse and phage T4 TSs, which contain intervening sequences. Comparisons of the DHFR-TS sequence with DHFR and TS sequences of other organisms indicate that (i) the order of enzymatic activities within the bifunctional polypeptide chain is DHFR followed by TS, (ii) the Leishmania bifunctional DHFR-TS evolved independently and not through a phage T4-related intermediate, and (iii) the rate of evolution of both the DHFR and TS domains has not detectably changed despite the acquisition of new functional properties by the bifunctional enzyme. The Leishmania gene is 86% G + C in the third codon position, in contrast to genes of the parasite Plasmodium falciparum, which exhibit an opposite bias toward A + T. The DHFR-TS locus is encoded within a region of DNA amplified in methotrexate-resistant lines, as previously proposed.
UR - http://www.scopus.com/inward/record.url?scp=0346707194&partnerID=8YFLogxK
U2 - 10.1073/pnas.83.8.2584
DO - 10.1073/pnas.83.8.2584
M3 - Article
C2 - 3458220
AN - SCOPUS:0346707194
VL - 83
SP - 2584
EP - 2588
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 8
ER -