Utilisation of 10-formyldihydrofolate as substrate by dihydrofolate reductase (DHFR) and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) tranformylase/IMP cyclohydrolase (PurH) in Escherichia coli

Sah, Shivjee and Shah, Riyaz Ahmad and Govindan, Ashwin and Varada, Rajagopal and Rex, Kervin and Varshney, Umesh (2018) Utilisation of 10-formyldihydrofolate as substrate by dihydrofolate reductase (DHFR) and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) tranformylase/IMP cyclohydrolase (PurH) in Escherichia coli. In: MICROBIOLOGY-SGM, 164 (7). pp. 982-991.

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Abstract

Dihydrofolate reductase (DHFR) and5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase/IMP cyclohydrolase (PurH) play key roles in maintaining folate pools in cells, and are targets of antimicrobial and anticancer drugs. While the activities of bacterial DHFR and PurH on their classical substrates (DHF and 10-CHO-THF, respectively) are known, their activities and kinetic properties of utilisation of 10-CHO-DHF are unknown. We have determined the kinetic properties (k(cat)/K-m) of conversion of 10-CHO-DHF to 10-CHO-THF by DHFR, and to DHF by PurH. We show that DHFR utilises 10-CHO-DHF about one third as efficiently as it utilises DHF. The 10-CHO-DHF is also utilised (as a formyl group donor) by PurH albeit slightly less efficiently than 10-CHO-THF. The utilisation of 10-CHO-DHF by DHFR is similar to 50 fold more efficient than its utilisation by PurH. A folate deficient Escherichia coli (Delta pabA) grows well when supplemented with adenine, glycine, thymine and methionine, the metabolites that arise from the one-carbon metabolic pathway. Notably, when the DpabA strain harboured a folate transporter, it grew in the presence of 10-CHO-DHF alone, suggesting that it (10-CHO-DHF) can enter one-carbon metabolic pathway to provide the required metabolites. Thus, our studies reveal that both DHFR and PurH could utilise 10-CHO-DHF for folate homeostasis in E. coli.

Item Type:	Journal Article
Publication:	MICROBIOLOGY-SGM
Publisher:	MICROBIOLOGY SOC
Additional Information:	Copy right for this article belong to MICROBIOLOGY SOC, CHARLES DARWIN HOUSE, 12 ROGER ST, LONDON WC1N 2JU, ERKS, ENGLAND
Keywords:	folate pathway; one-carbon metabolic pathway; DHF; 10-CHO-DHF; THF; 10-CHO-THF; DHFR; PurH
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	14 Sep 2018 14:54
Last Modified:	14 Sep 2018 14:54
URI:	http://eprints.iisc.ac.in/id/eprint/60667

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